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  • richardmitnick 12:14 pm on October 21, 2016 Permalink | Reply
    Tags: , , Earthquake, Magnitude-7.1 Kumamoto earthquake, Mt Aso in Japan,   

    From COSMOS- “Japanese volcano interrupted an earthquake: study” 

    Cosmos Magazine bloc

    COSMOS

    21 October 2016
    Amy Middleton

    It looks like Mt Aso’s magma chamber stifled part of the magnitude-7.1 Kumamoto earthquake in April, but that stress might boost its activity, seismologists warn.

    1
    The largest active volcano in Japan, Mount Aso, may have put stopped a 7.1-magnitude earthquake in its tracks. STR / AFP / Getty Images

    When an earthquake tore down a fault line in Japan in April this year, its destructive course may have been halted early thanks to a crater beneath a nearby volcano.

    A day after the magnitude-7.1 Kumamoto earthquake struck Kyushu Island in southwest Japan, Japanese seismologists, led by Aiming Lin of Kyoto University, headed into the field to investigate its passage.

    According to their paper published in Science today, the quake had torn through 40 kilometres of earth along the Hinagu–Futagawa Fault Zone, as well as a series of newly discovered faults, in close proximity to nearby Mt Aso – one of the world’s largest active volcanoes.

    Although experts know there’s a relationship between volcano and earthquake activity, it’s a tricky interaction to study because examples don’t come up too often.

    The proximity of this quake to Mt Aso presented a rare opportunity.

    The researchers identified new faultlines cut into a 380-kilometre-wide crater that forms part of Mt Aso. Interestingly, the rupture that cut into the volcanic crater – also known as a caldera – terminated suddenly.

    The cause of this interruption, the researchers suggest, was the magma chamber under the volcanic crater around three kilometres beneath the Aso caldera.

    At the depth of the magma chamber, around six kilometres below the crater, the quake’s ruptures ceased, probably because the magma chamber’s extreme temperature (around 580 °C) sent the seismic pressure upwards instead of continuing its path.

    “Magma is fluid so it absorbs stress,” says Lin.

    “That’s why the damage – the co-seismic rupturing – shouldn’t travel any further.”

    This change in pressure direction created a new series of stress fields beneath the active volcano.

    Importantly, the researchers suggest the new ruptures under the caldera could potentially trigger an eruption of Mt Aso in the near future and they urge experts keep a close eye on its activity.

    See the full article here .

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  • richardmitnick 8:39 am on October 6, 2016 Permalink | Reply
    Tags: Earthquake, Salton Trough Fault, ,   

    From Science Alert: “A SECOND fault line running parallel to San Andreas has just been identified” 

    ScienceAlert

    Science Alert

    And it might be holding everything together.

    5 OCT 2016
    BEC CREW

    1
    The San Andreas Fault. Credit: US Geological Survey

    Just days after a cluster of more than 200 small earthquakes shook the Salton Sea area of Southern California, scientists have found evidence of a second fault line that runs parallel to the massive San Andreas Fault – one of the state’s most dangerous fault lines.

    The new fault appears to run right through the 56-km-long Salton Sea in the Colorado Desert, to the west of the San Andreas Fault. Now that we know it’s there, seismologists will be forced to reassess earthquake risk models for the greater Los Angeles area.

    “This previously unidentified fault represents a new hazard to the region and holds significant implications for fault models … and, consequently, models of ground-motion prediction and southern San Andreas Fault rupture scenarios,” the team from the Scripps Institution of Oceanography and the Nevada Seismological Laboratory reports.

    Now known as the Salton Trough Fault, the newly mapped fault has been hidden for all this time because it’s submerged beneath the Salton Sea – a vast, salty rift lake that formed as a result of all the tectonic activity in the area.

    The team had to use an array of instruments, including multi-channel seismic data, ocean-bottom seismometers, and a surveying method called light detection and ranging (LiDAR), to precisely map fault inside several sediment layers both in and surrounding the lakebed.

    “The location of the fault in the eastern Salton Sea has made imaging it difficult, and there is no associated small seismic events, which is why the fault was not detected earlier,” says Scripps geologist Neal Driscoll.

    Oddly enough, the fact that we now know there’s an extra fault line running parallel to the San Andreas Fault doesn’t necessarily mean the area is more prone to earthquakes than we originally thought.

    It might actually solve the mystery of why the region has been experiencing LESS earthquakes than expected.

    As the team explains, recent research has revealed that the region has experienced magnitude-7 earthquakes roughly every 175 to 200 years for the last 1,000 years.

    But that’s not been the case more recently. In fact, a major rupture on the southern portion of the San Andreas Fault has not occurred in the last 300 years, and researchers think the region is long overdue for a major quake.

    Now they have to figure out what role the Salton Trough Fault could have played in all that.

    “The extended nature of time since the most recent earthquake on the Southern San Andreas has been puzzling to the earth sciences community,” said one of the Nevada team, seismologist Graham Kent.

    “Based on the deformation patterns, this new fault has accommodated some of the strain from the larger San Andreas system, so without having a record of past earthquakes from this new fault, it’s really difficult to determine whether this fault interacts with the southern San Andreas Fault at depth or in time.”

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    A map of the new fault line, STF. Credit: Sahakian et. al.

    On Monday morning, ominous rumblings started to emanate from deep underneath the Salton Sea, and then a ‘swarm’ of small earthquakes – three measuring above magnitude 4 – ruptured at the nearby Bombay Beach.

    The ruptures continued for roughly 24 hours, with more than 200 small earthquakes having been recorded in the area.

    These small earthquakes – or temblors – were not very severe, but this is just the third time since records began in 1932 that the area has experienced such an event. And this one had more earthquakes than both the 2001 and 2009 events.

    The event caused the US Geological Survey to increase the estimated risk of a magnitude 7 or greater earthquake in the next week from to between 1 in 3,000 and 1 in 100. To put that in perspective, without any quake swarms, the average risk for the area sits at around 1 in 6,000.

    Fortunately, the increased risk now appears to have passed, and according to the Los Angeles Times, California governor’s Office of Emergency Service just announced that the earthquake advisory period is now officially over.

    Of course, for those living in the area, it’s cold comfort, because the southern San Andreas Fault is still “locked, loaded, and ready to go”. Let’s hope the discovery of the Salton Trough Fault will make it easier for seismologists to at least predict when that will happen.

    The research has been published in the Bulletin of the Seismological Society of America.

    See the full article here .

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  • richardmitnick 3:10 pm on May 13, 2016 Permalink | Reply
    Tags: , Earthquake, ,   

    From U Hawaii: “Probability of Aleutians mega-earthquake estimated” 

    U Hawaii

    University of Hawaii

    May 13, 2016
    Marcie Grabowski

    1
    The map showing the Aleutians with respect to Hawaiʻi. The red and yellow arcs indicate the sections of the Aleutian subduction zones considered in the probability analysis. Stars and dates indicate epicenters of prior 20th century great earthquakes (Mw > 8). (credit: Butler et al., 2016)

    A team of researchers from the University of Hawaiʻi at Mānoa published* a study this week that estimated the probability of a magnitude 9+ earthquake in the Aleutian Islands—an event with sufficient power to create a mega-tsunami especially threatening to Hawaiʻi. In the next 50 years, they report, there is a 9 percent chance of such an event. An earlier State of Hawaiʻi report (PDF) (Table 6.12) has estimated the damage from such an event would be nearly $40 billion, with more than 300,000 people affected.

    Earth’s crust is composed of numerous rocky plates. An earthquake occurs when two sections of crust suddenly slip past one another. The surface where they slip is called the fault, and the system of faults comprises a subduction zone. Hawaiʻi is especially vulnerable to a tsunami created by an earthquake in the subduction zone of the Aleutian Islands.

    Back to basics

    “Necessity is the mother of invention,” said Rhett Butler, lead author and geophysicist at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST). “Having no recorded history of mega tsunamis in Hawaiʻi, and given the tsunami threat to Hawaiʻi, we devised a model for magnitude 9 earthquake rates following upon the insightful work of David Burbidge** and others.”

    Butler and co-authors Neil Frazer (SOEST) and William Templeton (now at Portland State University) created a numerical model based only upon the basics of plate tectonics: fault length and plate convergence rate, handling uncertainties in the data with Bayesian techniques.

    Using the past to inform the future

    To validate this model, the researchers utilized recorded histories and seismic/tsunami evidence related to the 5 largest earthquakes (greater than magnitude 9) since 1900 (Tohoku, 2011; Sumatra-Andaman, 2004; Alaska, 1964; Chile, 1960 and Kamchatka, 1952).

    “These five events represent half of the seismic energy that has been released globally since 1900,” said Butler. “The events differed in details, but all of them generated great tsunamis that caused enormous destruction.”

    To further refine the probability estimates, they took into account past (prior to recorded history) tsunamis—evidence of which is preserved in geological layers in coastal sediments, volcanic tephras, and archeological sites.

    “We were surprised and pleased to see how well the model actually fit the paleotsunami data,” said Butler.

    Mitigating the risk

    Using the probability of occurrence, the researchers were able to annualize the risk. They report the chance of a magnitude 9 earthquake in the greater Aleutians is 9 percent ± 3 percent in the next 50 years. Hence the risk is 9 percent of $40 billion, or $3.6 billion. Annualized, this risk is about $72 million per year. Considering a worst-case location for Hawaiʻi limited to the Eastern Aleutian Islands, the chances are about 3.5 percent in the next 50 years, or about $30 million annualized risk. In making decisions regarding mitigation against this $30-$72 million risk, the state can now prioritize this hazard with other threats and needs.

    The team is now considering ways to extend the analysis to smaller earthquakes, magnitude 7–8, around the Pacific.

    1
    The only well-documented paleotsunami deposit in Hawaiʻi from the 16th century is on Kauaʻi. The Makauwahi sinkhole, on the side of a hardened sand dune, is viewed toward the southeast from an apparent altitude of 342 m. Inset photos show two of the wall edges, indicating the edges of the sinkhole. The east wall, left, is 7.2 m above mean sea level and about 100 m from the ocean. Note for scale the people in the right image. (photo credits: R. Butler, left, Gerard Fryer, right, GoogleMaps, background and figure from Butler et al., 2014)

    *Science paper:
    Bayesian Probabilities for Mw 9.0+ Earthquakes in the Aleutian Islands from a Regionally Scaled Global Rate

    **Science paper:
    A Probabilistic Tsunami Hazard Assessment for Western Australia

    See the full article here .

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    System Overview

    The University of Hawai‘i System includes 10 campuses and dozens of educational, training and research centers across the Hawaiian Islands. As the public system of higher education in Hawai‘i, UH offers opportunities as unique and diverse as our Island home.

    The 10 UH campuses and educational centers on six Hawaiian Islands provide unique opportunities for both learning and recreation.

    UH is the State’s leading engine for economic growth and diversification, stimulating the local economy with jobs, research and skilled workers.

     
  • richardmitnick 10:40 am on May 5, 2016 Permalink | Reply
    Tags: , Earthquake, ,   

    From Science Alert: “Scientist says the San Andreas fault is ‘locked, loaded, and ready to roll’ “ 

    ScienceAlert

    Science Alert

    5 MAY 2016
    FIONA MACDONALD

    That can’t be good.

    1
    Southern California Earthquake Centre

    California’s San Andreas fault has been quiet for far too long and is overdue for a major earthquake, a leading geoscientist has announced. In a conference this week, the state was warned to prepare for a potential earthquake as strong as magnitude 8.0.

    “The springs on the San Andreas system have been wound very, very tight. And the southern San Andreas fault, in particular, looks like it’s locked, loaded and ready to go,” said Thomas Jordan, director of the Southern California Earthquake Centre.

    Jordan gave his warning in the keynote talk of the annual National Earthquake Conference in Long Beach, the Los Angeles Times reports.

    Here’s why he’s so worried: research has shown that the Pacific plate is moving northwest relative to the North American plate at a rate of around 5 metres (16 feet) every 100 years – and that’s building up a whole lot of tension along the San Andreas fault line that needs to be relieved regularly.

    But the last time southern California experienced a major shake-up was in 1857, when a magnitude 7.9 quake rupture almost 300 km (185 miles) between Monterey County and the San Gabriel Mountains.

    Further south, areas of the fault line have been quiet even longer, with San Bernardino county not moving substantially since 1812, and the region near the Salton Sea remaining still since the late 1600s.

    All of this means that there’s a lot of tension underneath California right now. Last year, Jordan’s team found there’s a 7 percent chance the state will experience a magnitude 8.0 quake in the next three decades.

    And that’s a big problem. Back in 2008, a US Geological Survey report* found that a magnitude 7.8 earthquake on the southern San Andreas fault could cause more than 1,800 deaths, 50,000 injuries, US$200 billion in damage, and long-lasting infrastructure disruptions – such as six months of compromised sewer systems and ongoing wildfires.

    Even though Los Angeles isn’t on the San Andreas fault line, simulations by the Southern California Earthquake Centre show that the shaking would quickly spread there:


    Access mp4 video here .

    According to their modelling, that size earthquake could cause shaking for nearly 2 minutes, said Jordan, with the strongest activity in the Coachella Valley, Inland Empire and Antelope Valley.

    The reason Los Angeles is at so much risk is because it’s built over a sedimentary basin, and the seismic waves spread and get trapped there to cause more extreme and longer-lasting shaking. As you can see in the magnitude 8.0 simulation:


    Access mp4 video here .

    While Jordan praised recent initiatives to earthquake retrofit buildings in LA, he warned that the rest of the state needs to get ready for the next big one, by making residents more aware of ways to stay safe during an earthquake and when and how to evacuate.

    “We are fortunate that seismic activity in California has been relatively low over the past century,” Jordan explained last year. “But we know that tectonic forces are continually tightening the springs of the San Andreas fault system, making big quakes inevitable.”

    *Science paper
    The ShakeOut Scenario

    See the full article here .

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  • richardmitnick 10:06 am on April 17, 2016 Permalink | Reply
    Tags: , , Earthquake, Ecuador   

    From CNN: “Ecuador earthquake: 77 killed, hundreds injured” 

    1
    CNN

    1

    April 17, 2016
    Faith Karimi and Steve Almasy, CNN

    A major earthquake hit Ecuador’s central coast, killing at least 77 people as it buckled homes and knocked out power in a city hundreds of miles away, authorities said.
    The magnitude-7.8 earthquake struck Saturday night, Vice President Jorge Glas said in a televised address.

    Nearly 600 people were injured, he said, adding that the death toll is expected to go up as more information comes in.

    A state of emergency is in effect for six provinces, but Glas urged those who left their homes in coastal areas to return, as the tsunami alert had been lifted.
    Provinces under a state of emergency are Guayas, Manabi, Santo Domingo, Los Rios, Esmeraldas and Galapagos.

    Nightlife venues closed

    Hours after the earthquake, the nation’s soccer federation said it has suspended the remaining matches of the current round of the Ecuadorean championship.
    The interior ministry also ordered all nightlife venues in affected areas closed for the next 72 hours.
    All mobile operators are allowing free text messages for customers to reach out to loved ones in Manabi and Esmeraldas provinces, the vice president said.
    In a race to help residents, Ecuador deployed 10,000 soldiers and 3,500 police officers to the affected areas, he said.
    The tremor was centered 27 kilometers (16.8 miles) southeast of the coastal town of Muisne, according to the U.S. Geological Survey.
    It’s the deadliest earthquake to hit the nation since March 1987, when a 7.2-magnitude tremblor killed 1,000 people, according to the USGS.

    Body recovered

    About 300 miles away in Guayaquil, the nation’s most populous city, emergency officials recovered one body from the scene of a bridge collapse, police told local media.

    2

    Elsewhere in the city of 2 million people, the earthquake left shoppers shaken. Video from a store showed kitchen utensils swinging back and forth as some items tumbled off shelves.
    Some areas in the city lost power.
    There were no immediate reports of damage or injuries in the capital of Quito, 173 kilometers (108 miles) from the epicenter of the earthquake.
    The Pacific Tsunami Warning Center said the tsunami threat following the earthquake has “mostly passed.”
    An earlier warning for other nations with coastlines on the Pacific was canceled.

    See the full article here .

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  • richardmitnick 7:15 pm on March 17, 2016 Permalink | Reply
    Tags: , Earthquake,   

    From Eos: “Tiny Accelerometers Create Europe’s First Urban Seismic Network” 

    Eos news bloc

    Eos

    3.17.16
    Antonino D’Alessandro

    The system, under development in Acireale, Italy, could be used to monitor earthquakes in real time and help rescue workers focus efforts where they’re needed most.

    1
    A view from Piazza Duomo, showing the dome of the Cathedral of Acireale (left) and the Basilica of Saints Peter and Paul (right) in Acireale, Italy. Scientists hope that a new urban seismic network will help protect people in and around these and other places in the city by letting officials know where to concentrate rescue efforts should an earthquake strike. Credit: Antonino D’Allesandro

    When a strong earthquake hits an urban area, prompt rescue operations can minimize the number of victims. Logically, the probability of saving a human trapped under debris or injured during the course of a disaster decreases exponentially as function of time, vanishing almost completely after about few hours. The Tokyo Fire Fighting Department Planning Section [2002] has quantified this further, stating that rescue within 3 hours is desirable and survival rate is drastically lower after 72 hours.

    Past disasters—like the magnitude 6.6 quake that struck Iran on 26 December 2003—support this assessment. As a result of that earthquake, more than 43,000 people died, and only 30 were saved, despite the intervention of 1600 rescuers from 43 nations. This tragic outcome is likely related to the fact that many rescuers didn’t arrive until after 3 days.

    The impact of a strong earthquake on an urban center can be considerably reduced by an efficient emergency management center, through timely and targeted actions immediately following the quake. A real-time urban seismic network—sensors laid out in a grid through a city—could help emergency management centers by providing immediate alert and postearthquake information summarized in maps of ground motion.

    Researchers are using new technological advances to develop one such urban seismic network in Acireale, Italy. The network will not use traditional seismometers; rather, they will harness the less expensive technology of accelerometers.

    2
    An accelerometer designed by the Archimedes Automated Assembly Planning Project at Sandia National Laboratory.

    Once operational, it will be the first urban seismic network in Europe.

    Goals of an Urban Seismic Network

    Urban seismic networks allow the disaster’s first responders to manage available resources, such as personnel and equipment needed to rescue people. Rescue operations and verification of damage to buildings could then be carried out according to a logical priority according to where the highest shaking was measured by the seismic network. Such an approach would minimize secondary effects induced by an earthquake and allow officials to protect critical infrastructure, thereby mitigating the economic and social costs of the earthquake.

    Accelerometers to the Rescue

    The high costs associated with the construction and installation of traditional seismic stations has made it nearly impossible to realize a true seismic network on an urban scale. However, recent technological developments in the field of microelectromechanical systems (MEMS) sensors, which can be configured to detect minute accelerations, may allow scientists to create an urban seismic network at low cost.

    3
    The internal devices that will constitute the MEMS accelerometric stations: the sensor, single-board computer, and GPS are manufactured by Phidgets Inc.

    MEMS sensors are a set of highly miniaturized devices that receive information from the environment and translate physical quantities they sense into electrical impulses. Depending on how the sensors are configured, they can measure phenomena of various kinds: mechanical (sound, acceleration, and pressure), thermal (temperature and heat flux), biological (cell potential), chemical (pH), optical (intensity of light radiation and spectroscopy), and magnetic (intensity of flow). The MEMS devices that will be used in the project integrate a three-axis accelerometer, which can measure both constant accelerations (usable as a tilt sensor) and those that vary in time (used to measure the oscillation induced by an earthquake).

    In the 1990s, MEMS sensors revolutionized the automotive airbag system and are today widely used in laptops, games controllers, drones, and mobile phones. When configured to measure ground shaking, the sensitivity and the dynamic range of these sensors are high enough to allow the researchers to record earthquakes of moderate magnitude even at a distance of several tens of kilometers [D’Alessandro and D’Anna, 2003; Evans et al., 2014]. Because of their low cost and their small size, MEMS accelerometers could be easily installed in urban areas to achieve a seismic network with a high density of measuring points.

    In the past decade, a number of research institutes that focus on geophysics and seismology have shown interest in this promising technology. In California and Japan, scientists are developing networks consisting entirely of MEMS sensors. These include the Quake-Catcher Network, managed by Stanford University [Cochran et al., 2009; Chung et al., 2011; Kohler et al., 2013]; the Community Seismic Network, managed by the California Institute of Technology [Clayton et al., 2011; Kohler et al., 2013]; and the Home Seismometer Network, managed by the Japan Meteorological Agency [Horiuchi et al., 2009].
    First European Urban Seismic Network

    In September 2015, the Italian Ministry of Education, University and Research funded a 3-year project to create the first European urban seismic network using MEMS technology. The project is called Monitoring of Earthquakes through MEMS Sensors (MEMS project).

    We chose the municipality of Acireale, Italy, an urban area particularly vulnerable to earthquake hazards [Azzaro et al., 2010, 2013], as a pilot site for the MEMS project. Acireale is located on the southeastern slopes of Sicily’s Etna volcano and is vulnerable to damage from tectonic and volcanic earthquakes.

    Founded in the 14th century, Acireale contains many seismically vulnerable buildings of historical and cultural value. In the past 2 centuries, more than 190 damaging earthquakes have occurred in the Etna region, almost 1 per year. This includes an earthquake sequence that began with a main shock on 29 October 2002—following this magnitude 4.4 event, more than 400 buildings in Acireale were declared uninhabitable [Azzaro et al., 2010].

    We aim to develop an urban seismic network comprising about 200 MEMS stations. Each station will consist of a three-axis digital MEMS accelerometer connected to a computer for on-site signals preprocessing. Each station will be supplied with a GPS for time synchronization and an Internet connection for data transmission to a processing center. Should an earthquake cause a power outage, the station can function autonomously for about 2 hours.

    The MEMS stations will be located mainly inside buildings characterized by high vulnerability (old buildings that weren’t built to withstand high shaking) and high flux of people moving in and out, such as schools, hospitals, public buildings, and places of worship. The geometry of the network will be designed to create homogeneous coverage of the urban center, with a high enough density of stations in the vicinity of the well-known faults.

    The network’s success will depend on our ability to implement algorithms able to prevent false alarms. Such algorithms will allow the creation of a shaking map only if a significant percentage of the MEMS stations have simultaneously detected a shaking event—if shaking is human made (e.g., an explosion), only the nearest stations would detect it, but an earthquake would be recorded by many stations. Automatic detection of patterns in waveforms that signal a specific seismic source will also be helpful.

    What Can We Learn?

    If all goes well, the network will be operational by the end of 2017. The seismic waveforms captured by the sensors will be processed in real time to identify several shaking parameters that will be used to create shake maps at the urban scale. The earthquake waveforms collected by the network will also be used to reconstruct the movement along the faults that caused the earthquakes to map seismic hazards and risks on a fine scale for the area covered.

    The system could be used to implement a site-specific earthquake early warning system [Horiuchi et al., 2009]. Such a system could enhance the safety margin of specific critical engineered systems—such as energy plants or high-speed railway networks—in real time, mitigating the seismic risk by triggering automatic actions that aim to shelter people from exposure to shaking.

    If successful, the MEMS project could provide a useful tool to reduce the seismic risk by increasing the safety of the population of the urban area covered by the network. Such a system could be quickly extended to other areas of high seismic risk, revolutionizing how communities monitor earthquakes. Communities would no longer need to focus on the characterization of earthquakes in terms of focus parameters (e.g., hypocenter and magnitude). Instead, networks like the MEMS project would characterize shaking by direct measurements of how shaking affects a city, neighborhood by neighborhood.

    References

    Azzaro, R., C. F. Carocci, M. Maugeri, and A. Torrisi (2010), Microzonazione sismica del versante orientale dell’Etna: Studi di primo livello, report, 184 pp., Le Nove Muse Editrice, Rome.

    Azzaro, R., S. D’Amico, L. Peruzza, and T. Tuvè (2013), Probabilistic seismic hazard at Mt. Etna (Italy): The contribution of local fault activity in mid-term assessment, J. Volcanol. Geotherm. Res., 251, 158–169, doi:10.1016/j.jvolgeores.2012.06.005.

    Chung, A. I., C. Neighbors, A. Belmonte, M. Miller, H. H. Sepulveda, C. Christensen, R. S. Jakka, E. S. Cochran, and J. F. Lawrence (2011), The Quake-Catcher Network rapid aftershock mobilization program following the 2010 M 8.8 Maule, Chile earthquake, Seismol. Res. Lett., 82(4), 526–532, doi:10.1785/gssrl.82.4.526.

    Clayton, R. W., et al. (2011). Community Seismic Network, Ann. Geophys., 54(6), 738–747, doi:10.4401/ag-5269.

    Cochran, E. S., J. F. Lawrence, C. Christensen, and R. S. Jakka (2009), The Quake-Catcher Network: Citizen science expanding seismic horizons, Seismol. Res. Lett., 80(1), 26–30, doi:10.1785/gssrl.80.1.26.

    D’Alessandro, A., and G. D’Anna (2003), Suitability of low cost 3 axes MEMS accelerometer in strong motion seismology: Tests on the LIS331DLH (iPhone) accelerometer, Bull. Seismol. Soc. Am., 103, 2906–2913, doi:10.1785/0120120287.

    Evans, J. R., R. M. Allen, A. I. Chung, E. S. Cochran, R. Guy, M. Hellweg, and J. F. Lawrence (2014), Performance of several low-cost accelerometers, Seismol. Res. Lett., 85, 147–158, doi:10.1785/0220130091.

    Horiuchi, S., Y. Horiuchi, S. Yamamoto, H. Nakamura, C. Wu, P. A. Rydelek, and M. Kachi (2009), Home seismometer for earthquake early warning, Geophys. Res. Lett., 36, L00B04, doi:10.1029/2008GL036572.

    Kohler, M. D., T. H. Heaton, and M.-H. Cheng (2013), The Community Seismic Network and Quake-Catcher Network: Enabling structural health monitoring through instrumentation by community participants, Proc. SPIE, 8692, 86923X, doi:10.1117/12.2010306.

    Tokyo Fire Fighting Department Planning Section (2002), New Fire Fighting Strategies, Tokyo Horei, Tokyo.
    Author Information

    Antonino D’Alessandro, Istituto Nazione di Geofisica e Vulcanologia, Rome, Italy; email: antonino.dalessandro@ingv.it

    Citation: D’Alessandro, A. (2016), Tiny accelerometers create Europe’s first urban seismic network, Eos, 97, doi:10.1029/2016EO048403. Published on 17 March 2016.

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 8:57 am on February 13, 2016 Permalink | Reply
    Tags: , Earthquake, , MyShake,   

    From livescience: “‘MyShake’ App Turns Your Smartphone into Earthquake Detector” 

    Livescience

    February 12, 2016
    Mindy Weisberger

    Earthquake

    Seismologists and app developers are shaking things up with a new app that transforms smartphones into personal earthquake detectors.

    By tapping into a smartphone’s accelerometer — the motion-detection instrument — the free Android app, called MyShake, can pick up and interpret nearby quake activity, estimating the earthquake’s location and magnitude in real-time, and then relaying the information to a central database for seismologists to analyze.

    In time, an established network of users could enable MyShake to be used as an early- warning system, the researchers said.

    UC Berkeley MyShake
    MyShake network

    Crowdsourcing quakes

    Seismic networks worldwide detect earthquakes and convey quake data to scientists around the clock, providing a global picture of the tremors that are part of Earth’s ongoing dynamic processes. But there are areas where the network is thin, which means researchers are missing pieces in the seismic puzzle. However, “citizen- scientists” with smartphones could fill those gaps, according to Richard Allen, leader of the MyShake project and director of the Berkeley Seismological Laboratory in California.

    “As smartphones became more popular and it became easier to write software that would run on smartphones, we realized that we had the potential to use the accelerometer that runs in every smartphone to record earthquakes,” Allen told Live Science.

    How it works

    Accelerometers measure forces related to acceleration: vibration, tilt and movement, and also the static force of gravity’s pull. In smartphones, accelerometers detect changes in the device’s orientation, allowing the phone to know exactly which end is up and to adjust visual displays to correspond to the direction it’s facing.

    Fitness apps for smartphones use accelerometers to pinpoint specific changes in motion in order to calculate the number of steps you take, for example. And the MyShake app is designed to recognize when a smartphone’s accelerometer picks up the signature shaking of an earthquake, Allen said, which is different from other types of vibrating motion, or “everyday shaking.”

    In fact, the earthquake-detection engine in MyShake is designed to recognize an earthquake’s vibration profile much like a fitness app recognizes steps, according to Allen.

    “It’s about looking at the amplitude and the frequency content of the earthquake,” Allen said, “and it’s quite different from the amplitude and frequency content of most everyday shakes. It’s very low-frequency energy and the amplitude is not as big as the amplitude for most everyday activities.”

    In other words, the difference between the highs and lows of the motion generated by an earthquake are smaller than the range you’d find in other types of daily movement, he said.

    Quake, rattle and roll

    When a smartphone’s MyShake app detects an earthquake, it instantly sends an alert to a central processing site. A network detection algorithm is activated by incoming data from multiple phones in the same area, to “declare” an earthquake, identify its location and estimate its magnitude, Allen said.

    For now, the app will only collect and transmit data to the central processor. But the end goal, Allen said, is for future versions of the app to send warnings back to individual users.

    An iPhone version of the app will also be included in future plans for MyShake, according to Allen.For seismologists, the more data they can gather about earthquakes, the better, Allen said. A bigger data pool means an improved understanding of quake behavior, which could help experts design better early warning systems and safety protocols, things that are especially critical in urban areas prone to frequent quake activity. With 2.6 billion smartphones currently in circulation worldwide and an anticipated 6 billion by 2020, according to an Ericsson Mobility Report released in 2015, a global network of handheld seismic detectors could go a long way toward keeping people safe by improving quake preparation and response.

    The findings were published online today (Feb. 12) in the journal Science Advances, and the MyShake app is available for download at myshake.berkeley.edu.

    See the full article here .

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  • richardmitnick 8:22 pm on February 3, 2016 Permalink | Reply
    Tags: , , Earthquake, EEW earthquake early-warning,   

    From Caltech: “White House Puts Spotlight on Earthquake Early-Warning System” 

    Caltech Logo
    Caltech

    02/03/2016
    Katie Neith
    Contact:
    Tom Waldman
    (626) 395-5832
    twaldman@caltech.edu

    Since the late 1970s, Caltech seismologist Tom Heaton, professor of engineering seismology, has been working to develop earthquake early-warning (EEW) systems—networks of ground-based sensors that can send data to users when the earth begins to tremble nearby, giving them seconds to potentially minutes to prepare before the shaking reaches them. In fact, Heaton wrote the first paper published on the concept in 1985. EEW systems have been implemented in countries like Japan, Mexico, and Turkey. However, the Unites States has been slow to regard EEW systems as a priority for the West Coast.

    Earthquake early warning EEW  UserDisplay
    The earthquake early warning (EEW) UserDisplay in action for a scenario M7.8 earthquake. The most intense colors correspond to very strong ground shaking. The banner on top shows expected shaking at the user site. The number “14” on the left indicates warning time, and the expected intensity at the user site is shown in roman numerals, VII. Other information indicates the epicenter and date/time of the earthquake.

    But on February 2, 2016, the White House held the Earthquake Resilience Summit, signaling a new focus on earthquake safety and EEW systems. There, stakeholders—including Caltech’s Heaton and Egill Hauksson, research professor in geophysics; and U.S. Geological Survey (USGS) seismologist Lucy Jones, a visiting associate in geophysics at Caltech and seismic risk advisor to the mayor of Los Angeles—discussed the need for earthquake early warning and explored steps that can be taken to make such systems a reality.

    At the summit, the Gordon and Betty Moore Foundation announced $3.6 million in grants to advance a West Coast EEW system called ShakeAlert, which received an initial $6 million in funding from foundation in 2011. The new grants will go to researchers working on the system at Caltech, the USGS, UC Berkeley, and the University of Washington.

    “We have been successfully operating a demonstration system for several years, and we know that it works for the events that have happened in the test period,” says Heaton. “However, there is still significant development that is required to ensure that the system will work reliably in very large earthquakes similar to the great 1906 San Francisco earthquake. This new funding allows us to accelerate the rate at which we develop this critical system.”

    In addition, the Obama Administration outlined new federal commitments to support greater earthquake safety including an executive order to ensure that new construction of federal buildings is up to code and that federal assets are available for recovery efforts after a large earthquake.

    The commitments follow a December announcement from Congressman Adam Schiff (D-Burbank) that Congress has included $8.2 million in the fiscal year 2016 funding bill specifically designated for a West Coast earthquake early warning system.

    “By increasing the funding for the West Coast earthquake early-warning system, Congress is sending a message to the Western states that it supports this life-saving system. But the federal government cannot do it alone and will need local stakeholders, both public and private, to get behind the effort with their own resources,” said Schiff, in a press release. “The early warning system will give us critical time for trains to be slowed and surgeries to be stopped before shaking hits—saving lives and protecting infrastructure. This early warning system is an investment we need to make now, not after the ‘big one’ hits.”

    ShakeAlert utilizes a network of seismometers—instruments that measure ground motion—widely scattered across the Western states. In California, that network of sensors is called the California Integrated Seismic Network (CISN) and is made up of computerized seismometers that send ground-motion data back to research centers like the Seismological Laboratory at Caltech.

    Here’s how the current ShakeAlert works: a user display opens in a pop-up window on a recipient’s computer as soon as a significant earthquake occurs in California. The screen lists the quake’s estimated location and magnitude based on the sensor data received to that point, along with an estimate of how much time will pass before the shaking reaches the user’s location. The program also gives an approximation of how intense that shaking will be. Since ShakeAlert uses information from a seismic event in progress, people living near the epicenter do not get much—if any—warning, but those farther away could have seconds or even tens of seconds’ notice.

    The goal is an improved version of ShakeAlert that will eventually give schools, utilities, industries, and the general public a heads-up in the event of a major temblor.

    Read more about how ShakeAlert works and about Caltech’s development of EEW systems in a feature that ran in the Summer 2013 issue of E&S magazine called Can We Predict Earthquakes?

    See the full article here .

    [If you live in an earthquake prone area, you can help with identification and notification by joing the Quake-Catcher Network, a project based at Caltech and running on software from BOINC, Berkeley Open Infrastructure for Network Computing. Please visit Quake-Catcher Network and see what it is all about.]

    BOINC WallPaper

    BOINC

    QCN Quake Catcher Network map
    Quake-Catcher Network map

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 11:58 am on January 3, 2016 Permalink | Reply
    Tags: , Earthquake, ,   

    From Nature: “The 24/7 search for killer quakes” July 2015 Just Found 

    Nature Mag
    Nature

    08 July 2015 [a golden oldie]
    Alexandra Witze

    Temp 1
    Seismologists at the National Earthquake Information Centre are on duty 24/7 to monitor quake activity.

    At 17 minutes past midnight on Saturday 25 April, Rob Sanders’s computer started chiming with alerts. On his screen, squiggly recordings poured in from seismometers in Tibet, Afghanistan and nearby areas that were feeling the first vibrations from a tremendous earthquake.

    Sanders was part way through his shift as an on-duty seismologist at the US Geological Survey’s National Earthquake Information Center (NEIC) in Golden, Colorado. It was his job to work out what was happening — and fast. Within 30 seconds, he began analysing the seismic data and realized it was time to call his boss.

    When the phone rang, Paul Earle was dozing in the room of his four-year-old son, where he had nodded off earlier that evening. Earle rolled out of bed and logged onto his home computer. As chief of 24/7 operations at the NEIC, Earle knew that time was short. For any major earthquake in the world, the US Geological Survey (USGS) is committed to publishing the shock’s magnitude and location online within 20 minutes. The team also puts out rapid estimates for how many people may have been hurt. Various nations issue alerts for quakes in their vicinity, but Earle’s crew is the only one that analyses tremors around the globe.

    The NEIC information helps governments and humanitarian groups to decide how to respond in times of crisis. It determines whether search-and-rescue teams pack their bags, and whether financial markets begin responding to a catastrophic natural disaster. When minutes count, hundreds of key responders — from the White House to the United Nations — rely on the NEIC team to tell them exactly how bad an earthquake was. On 25 April, the work that began on Sanders’s screen ended up with the US government dispatching a response team to the quake’s epicentre in Nepal within hours.

    The NEIC seismologists do not always get it right. Sometimes, deceived by the rawness of the data, they put out an alert containing the wrong quake location or size, before quickly retracting the information. But they are continually refining their techniques to speed up response times while maintaining accuracy. “Being reliable is more important than pure speed,” says Earle.

    The night shift

    The NEIC takes up the fifth floor of a blocky building on the campus of the Colorado School of Mines in Golden, not far from the original Coors brewery and bronze sculptures of the miners who shaped this region of Colorado. A decade ago, television satellite trucks regularly clogged the car park after any large earthquake. Now, most of the journalists stay at home — they can get information from the centre faster over the Internet.

    Computer monitors have replaced the slowly rotating paper drums that once displayed the vibrations measured at seismic stations around the world. But the centre has kept one relic on display: a large wooden globe that often appeared in television reports. Patches of its coloured surface are worn away from decades of seismologists jabbing their fingers at earthquake locations. Southern California has basically disappeared. So has Japan.

    Established in 1966, the NEIC originally operated during normal business hours, with seismologists on call at other times. But in 2004, a magnitude-9.1 earthquake hit Sumatra, triggering a ruinous tsunami that killed almost a quarter of a million people around the Indian Ocean. In an effort to improve its response times in major disasters, the earthquake centre moved to operating around the clock. Fourteen seismologists now cover three shifts, with at least two people on duty at any given time (coordinating their toilet and meal breaks).

    The NEIC analyses more than 20,000 earthquakes a year, everything from imperceptible ones in California to the monsters that occasionally shake the globe. It reports on any earthquake of magnitude 5 or greater worldwide, and down to magnitude 3 in parts of the United States.

    On 25 April, the only earthquake that mattered began beneath Nepal. The jolt started 15 kilometres underground, on the huge Himalayan fault where the tectonic plate carrying India rams into Asia. At 11:56 a.m. local time (11 minutes past midnight in Colorado), the stress of that geological collision ruptured a 120-kilometre-long segment of Earth’s crust beneath the Nepalese district of Gorkha. Waves of seismic energy raced outwards in all directions.

    Within 16 seconds they reached Kathmandu, almost 80 kilometres to the southeast, and began toppling thousands of buildings. Just over a minute later they passed Lhasa, 600 kilometres northeast of the epicentre, and shook seismometers bolted into granite in a hillside tunnel. Those machines, part of the Global Seismographic Network, immediately relayed their data to the NEIC.

    At the Colorado centre, an alert dinged and a window popped up on Sanders’s screen, which filled with information from stations around Asia. Sanders started sorting through the data, choosing the best seismic records to include in his analysis.

    A second seismologist on duty that night called and woke Earle, who began to work on the seismic data from home. As the minutes ticked away, the three of them faced a crucial task — deciding on the quake’s magnitude. The USGS measures eight types of magnitude, each of which conveys different information about the strength of an earthquake’s vibrations and the amount of energy it releases. Certain magnitude scales are most accurate for smaller quakes, whereas others are better at describing long-lasting, larger shocks.

    At 12:29:42 a.m. — 18 minutes and 16 seconds after the earthquake began — the NEIC released its first answer. Location: 77 kilometres northwest of Kathmandu. Size: 7.5 on the moment magnitude scale. This particular scale relies on computer modelling of a certain type of seismic wave, and Earle chose it because of a gut feeling for what he thought would represent the most meaningful magnitude.

    But as is often the case with large quakes, the first official magnitude was not the last. The team had only just started its analyses. Earle called and woke up two more colleagues — Harley Benz and Gavin Hayes — then jogged the two blocks from his home into work. Even as news agencies began broadcasting alerts of a magnitude-7.5 earthquake in Nepal, the NEIC researchers were sifting through fresh data.

    From his home, Hayes ran a separate set of model calculations, which use data on longer-period seismic waves that arrive at stations later but are more appropriate for the world’s largest quakes. At 1:04 a.m., on the basis of this ‘W-phase’ analysis, the NEIC updated the Nepal quake’s magnitude to 7.9.

    Temp 4
    Paul Earle and the team at the earthquake centre issue alerts for major quakes within 20 minutes. Barry Gutierrez

    “None of those numbers are wrong,” says Earle. “They’re all right for that particular magnitude scale.” (Three hours later, the centre would announce a final magnitude of 7.8, also based on the W-phase approach but incorporating more-detailed modelling with newer data.)

    Even as Earle was wrestling with the quake’s magnitude, he called NEIC seismologist David Wald, who happened to be awake. Wald runs a set of programs that take the initial magnitudes and estimate possible fatalities and economic losses. The system, called PAGER (Prompt Assessment of Global Earthquakes for Response), relies on databases of where people live, the types of building in the region of an earthquake and how many people had been killed in similar quakes in the area before.

    If a quake is big enough, PAGER sends out alerts automatically. At 12:34 a.m., the system used the initial magnitude of 7.5 to predict between 100 and 1,000 deaths, and damages between US$10 million and $100 million. That ranked it an ‘orange’, the second-highest alert on the PAGER colour-coded system. “That’s when we knew it was going to be deadly,” Wald says.

    As the minutes crept by, aftershocks kept pummelling Kathmandu. PAGER automatically updated three more times at the orange level, the last at 2:16 a.m.. Then Wald took some data on how much the ground had moved and how widespread the aftershocks were, and manually fed the fresh information into PAGER. The alert immediately escalated to red, estimating between 1,000 and 10,000 deaths. It was 4:14 a.m..

    Global response

    In Washington DC, Gari Mayberry’s mobile phone woke her up with the first NEIC alert. Mayberry, a USGS volcanologist, advises the US Agency for International Development on natural hazards. The agency funded PAGER’s development, precisely to simplify split-second decisions after earthquakes. “Do I need to call my boss at 3 a.m.?” asks Mayberry. “That’s what people want to know.”

    For Nepal, the answer was yes. As the Colorado team released its analyses, Mayberry quickly fed information to her bosses, who help to coordinate search-and-rescue teams for international disasters. In such situations, she says, every minute counts. Within hours, the US government had a team on the way to Nepal.

    Other groups also rolled into action. Gisli Olafsson in Reykjavik, who directs emergency response for a consortium of 43 humanitarian groups called NetHope, says: “I always look at PAGER once it becomes available.” Studying the USGS information, he was relieved to see that the shock had originated relatively far from Kathmandu. But he also learned that the quake had struck in mountainous terrain on a fault close to Earth’s surface, which meant that it had probably destroyed roads. NetHope immediately started preparing for the complicated logistics of getting in and out of rural areas with limited access, and Olafsson flew to Kathmandu to coordinate its response.

    Even the financial world got involved: the Inter-American Development Bank uses PAGER numbers to trigger payouts on catastrophe bonds, a type of insurance against natural disasters such as earthquakes.

    The most recent estimates suggest that the 25 April earthquake and its aftershocks, including a magnitude 7.3 on 12 May, killed roughly 8,700 people — close to the PAGER estimates of around 10,000 deaths. Other catastrophe experts had estimated 50,000 dead or more, using independent assessments of population exposure and building vulnerability.

    One factor that may have saved lives in Kathmandu was how buildings were constructed, says Kishor Jaiswal, a civil engineer at the NEIC. Many of the newer buildings in the city have concrete frames reinforced with steel bars, which kept a lot of them from collapsing. Jaiswal had previously analysed this construction, and his work was one reason that the PAGER fatality estimates were relatively low. Although the toll was great, he knew that much of the city would survive.

    Need for speed

    Most of the NEIC’s work is much calmer than on the night of the Nepalese disaster. Of the thousands of earthquakes that the team tracks every month, the vast majority do not kill anyone. Earle, Benz and Hayes spend their time developing ways to analyse earthquake ruptures as quickly and accurately as possible. Hayes, for instance, specializes in ‘moment tensor’ and ‘finite fault’ calculations, both of which convey information about exactly how a fault has ruptured.

    One of Earle’s top priorities for the earthquake centre is to avoid making major mistakes, although his team sometimes does err. Notable bloopers include issuing an alert on Christmas Day 2013 for a magnitude-22 earthquake. It was supposed to say magnitude 2.2; the typo caused the NEIC to remove all human typing from the real-time system.

    And in May this year, the USGS reported several phantom quakes in California — in reality, they were vibrations from more-distant shocks in Alaska and Japan. An on-duty seismologist had caught the problem, but the software that distributes the alerts had not responded to the correction.

    Cutting back on false alerts while making sure that the real ones get out in time takes a nuanced mix of skill and speed. The NEIC gets data from nearly 1,800 stations worldwide, but there are gaps that slow the seismic analyses. China’s national seismological alerting network puts a 30-minute delay on much of the information, so Earle’s team can rarely use it. And India does not release its seismic data. Nepal, where seismologists have long warned about the earthquake risk, did not have a single station feeding real-time data into the USGS system. Had the agency received more real-time data from locations closer to the epicentre, seismologists could have accurately located the Nepal quake faster than they did, says Thorne Lay, a seismologist at the University of California, Santa Cruz.

    Even with all its speed, the NEIC is not the fastest earthquake-alert system in the United States. That title goes to the National Oceanic and Atmospheric Administration’s two tsunami-warning centres. Drawing on the same seismic network, they release rougher magnitudes and locations within 3 minutes of an earthquake striking, but they handle only shocks in oceans near US territory.

    The NEIC keeps pushing to shave as many seconds off its own notifications as possible. One ongoing project involves Twitter. Earle has set up an automated system that hunts for words such as ‘earthquake’ in various languages in tweets from around the world (P. Earle Nature Geosci. 3, 221–222; 2010). He has to filter out unrelated instances, including references to the video game Quake, but once that is done he can get a heads-up that something big is beginning. When someone in Indonesia tweets ‘gempa’, or earthquake, “it’s on our server in five seconds,” he says.

    Tweets can arrive at the NEIC faster than seismic waves can reach recording stations. In 2012, a magnitude-4.0 jolt in Maine set off a stream of tweets from the region around the epicentre. Earle got an automatic text notification before the shaking spread across New England. “I was at Safeway buying groceries, and I knew about the quake, from nothing but Twitter data, before other people felt it,” he says.

    The Twitter experiment is most useful in places where the USGS does not receive a lot of real-time data, such as parts of South America or Indonesia. Although it will never replace the NEIC’s conventional methods, it can alert the seismologists there to keep a lookout for incoming data.

    The earthquakes never stop coming. Towards the end of a long Friday afternoon in May, Earle is at his standing desk when his iPhone buzzes with a report of a magnitude-6.9 quake in the Solomon Islands. “That one isn’t going to be near a populated area, but it’s a big quake,” he says. “I’m gonna get someone.” He is heading out of the door nearly before he finishes the sentence.

    Earle speed-walks down the hallway, past the row of display monitors set up for television cameras, and pokes his head into the office of seismologist Jana Pursley. “Jana, have you got that?” he asks. “No, Sean does,” she says, waving her hand at the on-duty seismologist down the hall. “OK,” says Earle. “Sean will release it, and then I’ll have Bruce review the moment tensors for it, and then we’ll be done.”

    With that earthquake sorted, Earle heads back to his office. He switches on the electric kettle that sits next to two containers of freeze-dried, generic-brand coffee. “I get the cheapest possible coffee because I don’t even taste it anymore,” he says. “I just drink it.”

    And he turns back to his monitor, to wait for the next one.

    Nature 523, 142–144 (09 July 2015) doi:10.1038/523142a

    See the full article here .

    You can help in earthquake response. You can join Quake-Catcher Network, a project at Caltech running on home computer laptops with software from BOINC, Berkeley Open Infrastructure for Network Computing. You visit the BOINC website, download and install the software, attach to the project. BOINC software uses the unused CPU cycles of your laptop computer to record the data, and send it back to the home base at Caltech. The area effected is then notified, literally in seconds, so that disaster relief agencies are alerted.

    BOINC WallPaper

    The Quake-Catcher Network (QCN) is a research project that uses Internet-connected computers to do research, education, and outreach in seismology. You can participate by downloading and running a free program on your computer. Currently only certain Mac (OS X) PPC and Intel laptops are supported — recent ones which have a built-in accelerometer. You can also buy an external USB accelerometer.

    Temp 3
    A map of the Quake-Catcher installed base

    QCN is based at the CalTech Division of Geological and Planetary Sciences (GPS). From 2007 to 2015 QCN was based at the Stanford University School of Earth Sciences.

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    Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.

     
  • richardmitnick 9:00 am on December 22, 2015 Permalink | Reply
    Tags: , , Earthquake   

    From AAAS: “Can electric signals in Earth’s atmosphere predict earthquakes?” 

    AAAS

    AAAS

    21 December 2015
    Julia Rosen

    1
    Scientists have detected electromagnetic anomalies before major earthquakes, like the magnitude 9.0 event that struck Japan in 2011, triggering a massive tsunami that wiped out coastal communities like Ōfunato, shown above. U.S. Navy photo by Mass Communication Specialist 1st Class Matthew M. Bradley

    Ask seismologists when they’ll be able to predict earthquakes, and the answer is generally: sometime between the distant future and never. Although there have been some promising leads over the years, the history of earthquake forecasting is littered with false starts and pseudoscience. However, some scientists think that Earth’s crust may give hints before it ruptures, in the form of electromagnetic anomalies in the ground and atmosphere that occur minutes to days before an earthquake. Last week, here at the fall meeting of the American Geophysical Union, researchers shared their evolving understanding of these phenomena—and how they might be used to predict deadly quakes.

    Kosuke Heki, a geophysicist at Hokkaido University in Sapporo, Japan, first got interested in the subject when he spotted an increase in the total electron content of the ionosphere—the charged outermost layer of the atmosphere—above Tohoku about 40 minutes before the magnitude 9.0 earthquake struck in 2011. Heki had long used GPS data to study ionospheric responses to earthquakes, which occur when the sudden movement of Earth’s crust reverberates through the atmosphere. Ionospheric disturbances interfere with the communication between GPS satellites and receivers, leaving a fingerprint at specific radio frequencies that researchers can tease out.

    In 2011, Heki was skeptical of electromagnetic precursors. But since then, he has used the world’s growing array of GPS stations to identify similar signals before nine other major earthquakes, he explained at the meeting. In addition, Heki has found that earlier anomalies precede stronger earthquakes, potentially reflecting the longer time needed to initiate rupture along larger segments of a fault. Now, he says he’s convinced there’s really something going on: “Seeing is believing.”

    However, scientists have yet to agree on a mechanism by which the crust could create electromagnetic signals. One idea is that rocks can generate positive charges when heated or stressed in the build-up to an earthquake, says Friedemann Freund, an adjunct professor of physics at San Jose State University in California and a senior scientist at NASA’s Ames Research Center in Mountain View, California. “When you stress a rock, it turns into a battery,” Freund says. “Not an electrochemical battery that you find in your car, but a new type of semiconductor battery that produces electrons and holes.”

    These “holes” are positive charges that come from molecular defects known as peroxy bonds, which occur in most crystalline rocks and involve two oxygen atoms bonded together instead of to silicon or another element. At high temperatures and pressures, peroxy bonds break, causing them to pull in an electron from a neighboring atom, and leave behind a positively charged “hole.” This creates a chain reaction of electrons flowing toward the peroxy defect, effectively creating a cloud of positive charge flowing away, potentially to the surface and beyond.

    With rocks, Freund says, “the faster you stress them, the more electricity becomes available.” He says this mechanism could explain numerous observations of strange occurrences before earthquakes, like mysterious lights emanating from the ground and the reported tendency for compass needles to dance around. Such positive charges may also propagate into the atmosphere to cause the ionospheric disturbances seen by Heki and others, although exactly how remains unclear.

    Freund and his collaborators, including John Scoville, a physicist at San Jose State University and the SETI Institute, have demonstrated the semiconducting behavior of rocks in laboratory experiments where they drop a 90-kilogram mass onto a slab of igneous rock. The electromagnetic pulses they create in their experiments are shorter and weaker than those observed before earthquakes, but Scoville attributes that to the vast differences in scales. “We just can’t possibly recreate the volumes of rock that are active in the Earth during earthquakes,” he says.

    The pulses they see in the lab do have the same shape—rising faster than they fall—as those seen in the field. At the meeting, Jorge Heraud of the Pontifical Catholic University of Peru in Lima reported that his team has detected magnetic pulses more than 2 weeks before recent earthquakes near Lima, using a pair of ground-based magnetometers designed specifically to look for earthquake precursors. In addition, Heraud said that his team has successfully identified the locations and depths of scores of future earthquakes each time, sending a letter to colleagues at his university in advance.

    Although magnetometers may be capable of picking up precursor signals in surface rocks, they have one major drawback: They must be located within 100 kilometers or so of the epicenter. That’s why Angelo de Santis, director of research at the National Institute of Geophysics and Volcanology in Rome, and others have turned to satellites to get a global view of what happens in the atmosphere before earthquakes. Through a new research initiative called SAFE (Swarm for earthquake study), de Santis and his colleagues will pair data from the European Space Agency’s Swarm satellites, launched in 2013, with those from traditional earthquake monitoring devices like seismometers and GPS stations.

    ESA Swarm
    ESA/Swarm

    Their goal, de Santis says, is first to understand the link between Earth’s crust and atmosphere. “If you understand the physics, you double the chances to make predictions,” he says. They will also study past earthquakes to identify any patterns that precede known ruptures, and then see whether those same patterns precede future earthquakes. Already, at the meeting, they reported finding ionospheric anomalies before the 2014 Iquique earthquake in Chile and the recent disaster in Nepal.

    However, many seismologists remain skeptical, including Tom Jordan, the director of the Southern California Earthquake Center in Los Angeles, who chaired a report on earthquake prediction and forecasting commissioned by the Italian government after the deadly L’Aquila earthquake in 2009. “We concluded that there was no evidence that ionospheric or electromagnetic precursors provide any diagnostic information about earthquakes in advance,” Jordan says.

    After all, true earthquake prediction requires determining the time, location, and magnitude of a quake in advance. So far, researchers have mainly looked for anomalies after the fact. That’s OK, as long as researchers don’t consider finding something a confirmation of their hypotheses, says Jeffrey Love, a geophysicist at the U.S. Geological Survey (USGS) in Denver. “The acid test is always predicting something that hasn’t happened yet,” Love says. One possibility, frequently cited by critics, is that these precursors are simply coincidences arising from the fact that Earth and its ionosphere are fairly noisy places, geomagnetically speaking.

    Another more problematic issue is that many seismologists are convinced, after decades of scrutiny, that the crust doesn’t undergo major changes before it ruptures that would produce precursor signals. And if anything does happen, it’s not clear that it would portend the size of an impending earthquake—the most critical parameter. “If it is the case that all earthquakes start alike, and that a big earthquake is simply an earthquake that went farther and longer, then that’s going to put some real cold water on the idea of earthquake prediction from precursors,” says Michael Blanpied with the USGS Earthquake Hazards Program.

    Blanpied thinks it’s unlikely that electromagnetic signals—or any other precursors, for that matter—will turn out to be “a smoking gun,” but he does think they merit attention, especially as researchers collect more and more data from an expanding network of sensors. “It may be that earthquakes are predictable only at a very, very marginal level,” he says, which may only become apparent by studying large datasets.

    These kinds of possibilities are worth pursuing, says Craig Dobson, a program scientist and manager at NASA headquarters in Washington, D.C., whose division funds research like Freund’s. As an investment strategy aimed at reducing the devastating toll of earthquakes, “it’s good to be supporting some things which may have a potentially very high pay off but seem somewhat risky and are not necessarily part of the mainstream,” Dobson says. “Ultimately, that’s often how large advancements are made.”

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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