From temblor: “State finds new active fault strands in Santa Monica, Beverly Hills, and Hollywood”

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temblor

July 18, 2017
David Jacobson
Ross Stein

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On 13 July, the California Geological Survey released four preliminary Earthquake Fault Zone maps for parts of Los Angeles and Napa counties. The West Los Angeles coverage provides new active fault ‘traces’ (where a fault intersects the Earth’s surface) and ‘zones’ (the areas in which some faulting could occur in an earthquake) for the Santa Monica Fault, the Hollywood Fault, and the Newport-Inglewood Fault. And, yes, the Hollywood Fault is responsible for lifting up one of L.A.’s most sacred landmarks, the “Hollywood” sign atop the Santa Monica Mountain range.

New Fault Zone Mapping

Because fault sections were added, revised, and removed, trillions of dollars of real estate is impacted by these new boundaries. This work is carried out under California law; if property lies within the Alquist-Priolo Earthquake Fault Zones that generally extend 150 meters to each side of a fault, special investigation is required prior to construction. These are preliminary review maps, which will not become official until at least January 11, 2018, but provide a chance to see what new fault research has revealed about the Hollywood, Santa Monica, and Newport-Inglewood Faults, which traverse a wealthy, densely-populated urban corridor.

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This map shows the old (current) and new (proposed) faults and ‘Alquist-Priolo’ Fault Zones for west Los Angeles. The preliminary “review maps” released by the California Geological Survey last week reveal a greater area at risk of experiencing earthquake slip. The new, higher resolution fault mapping in red can be compared to the cruder older mapping in blue. The revised Santa Monica Fault would be capable of M=6.7 earthquake. (Data from: California Geological Survey)

The Fault Zones limit residential and commercial development

Alquist-Priolo Zones are defined as regulatory perimeters around active faults. According to Tim Dawson, a senior engineering geologist for the California Geological Survey, these zones are “intended to capture the most hazardous faults that could produce surface displacements of concern to a building.” While a fault rupture can be confined to zones just a few meters (10 ft), because of the uncertainty of the fault location and the possibility of slip on a distributed band of faults, the state makes the zones ~150 meters (500 ft) on either side of the mapped trace of a fault.

If a property is within a Fault Zone, strict guidelines must be followed if new construction or major renovations are planned. Further, development is prohibited directly on active faults found within these zones . All of this is done to ensure public safety. Therefore, new maps like the ones released last week will have significant impacts.

High resolution fault mapping is extremely difficult in densely populated and heavily landscaped areas. Brian Olson, a California Geological Survey engineering geologist used existing maps, radar topographic imagery (LIDAR), old aerial photos, and field observations.

Dr. Rufus Catchings of the U.S. Geological Survey performed a shallow geophysical survey that determined the subsurface geometry of the Santa Monica Fault in the vicinity of the Veterans Administration Hospital (Catchings et al., 2008).

Additionally, Tim Dawson said that, “Professor James Dolan at USC conducted a paleoseismic investigation at the Veterans Administration Hospital on the Santa Monica fault. Other faults studies have been conducted by consultants at schools in the area, as well as other studies done for the proposed LA Metro Purple Line Subway Extension.” In the map above, the old and new fault traces and Alquist-Priolo (A-P) Zones are shown to illustrate the changes. One of these changes is the addition of a 6.3 km2 zone cutting through Beverly Hills, Westwood and Santa Monica.

Which fault sections disappeared, and which were added?

The southernmost 5 km (3 mi) section of the Santa Monica Fault, which formerly sliced through a coveted beach community, has been removed. The fault should have been visible in the Santa Monica bluff face, and probably was not found. This trace also was not expressed in the topography, another clue that it had been mislocated. The central two sections remained, and a new one was added to the north. So, in effect, the fault has migrated closer to the range front of the Santa Monica Mountains.

Prior to the new mapping, there were four discontinuous faults running through Santa Monica. Now, the 5-km-long (3 mi) northern-most section of the Newport-Inglewood Fault, which ruptured in the 1933 M=6.4 Long Beach earthquake, has been removed entirely, and so the Newport-Inglewood and Santa Monica Faults are no longer connected.

What does this mean for earthquake rupture?

But there is now more connectivity and continuity between the Hollywood and Santa Monica Faults, making a through-going rupture more likely, which, if it encompassed the adjacent Raymond Fault could reach Magnitude~7. On the other hand, the possibility of a joint rupture of the northern Newport-Inglewood and Santa Monica Faults is now diminished. The revised 12 km-long fault section of the Santa Monica fault has a high degree of continuity, permitting a M≤6.7 rupture, similar to the 1971 San Fernando or 1994 Northridge earthquake.

Fault traces to green belts

Wouldn’t it be ideal if all these fault traces were turned into green belts? This would be the most appropriate and most valuable use of this land.

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Just imagine if all fault traces running through urban areas were turned into green belts like this. (Photo from: Pinterest)

The Right Stuff

These changes in fault traces highlight the importance of continually researching and remapping urban faults, as only with better knowledge can we prepare for the earthquakes which will inevitably happen. Nowhere is this more difficult—or more important—than in dense urban areas like this one.

References
California Geological Survey Press Release dated July 13, 2017: Link

California Geological Survey PDF Map for Preliminary Review: Link

Webpage for the Alquist-Priolo Earthquake Fault Zoning Act: Link

Rong-Gong Lin II and Raoul Rañoa, ‘Earthquake fault maps for Beverly Hills, Santa Monica and other Westside areas could bring development restrictions’ (Los Angeles Times, 13 July 2017): Link

R. D. Catchings, G. Gandhok, M. R. Goldman, D. Okaya, M. J. Rymer, and G. W. Bawden, Near-Surface Location, Geometry, and Velocities of the Santa Monica Fault Zone, Los Angeles, California, Bulletin of the Seismological Society of America, Vol. 98, No. 1, pp. 124–138, February 2008, doi: 10.1785/0120020231.

Olson, Brian, 2017, The Hollywood, Santa Monica, and Newport-Inglewood Faults in the Beverly Hills and Topanga 7½-minute Quadrangles, Los Angeles County, California: California Geological Survey, Fault Evaluation Report #259, 72 pages of text and figures; Plate 1, Compilation of Historical Fault Mapping; Plate 2, Geomorphology of Beverly Hills and Topanga Quadrangles; Plate 3, Recommended Fault Zones for Hollywood Fault, Newport-Inglewood Fault, and Santa Monica Fault.

Acknowledgements
We would like to thank Tim Dawson (California Geological Survey) and Robert H. Sydnor for reviewing this post and for providing valuable insight.

See the full article here .

Please help promote STEM in your local schools.

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Stem Education Coalition

You can help many citizen scientists in detecting earthquakes and getting the data to emergency services people in affected area.
QCN bloc

Quake-Catcher Network

The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

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The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

Below, the QCN Quake Catcher Network map
QCN Quake Catcher Network map

Earthquake country is beautiful and enticing

Almost everything we love about areas like the San Francisco bay area, the California Southland, Salt Lake City against the Wasatch range, Seattle on Puget Sound, and Portland, is brought to us by the faults. The faults have sculpted the ridges and valleys, and down-dropped the bays, and lifted the mountains which draw us to these western U.S. cities. So, we enjoy the fruits of the faults every day. That means we must learn to live with their occasional spoils: large but infrequent earthquakes. Becoming quake resilient is a small price to pay for living in such a great part of the world, and it is achievable at modest cost.

A personal solution to a global problem

Half of the world’s population lives near active faults, but most of us are unaware of this. You can learn if you are at risk and protect your home, land, and family.

Temblor enables everyone in the continental United States, and many parts of the world, to learn their seismic, landslide, tsunami, and flood hazard. We help you determine the best way to reduce the risk to your home with proactive solutions.

Earthquake maps, soil liquefaction, landslide zones, cost of earthquake damage

In our iPhone and Android and web app, Temblor estimates the likelihood of seismic shaking and home damage. We show how the damage and its costs can be decreased by buying or renting a seismically safe home or retrofitting an older home.

Please share Temblor with your friends and family to help them, and everyone, live well in earthquake country.

Temblor is free and ad-free, and is a 2017 recipient of a highly competitive Small Business Innovation Research (‘SBIR’) grant from the U.S. National Science Foundation.

ShakeAlert: Earthquake Early Warning

The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications by 2018.

The primary project partners include:

United States Geological Survey
California Governor’s Office of Emergency Services (CalOES)
California Geological Survey
California Institute of Technology
University of California Berkeley
University of Washington
University of Oregon
Gordon and Betty Moore Foundation

The Earthquake Threat

Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

Part of the Solution

Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds, depending on the distance to the epicenter of the earthquake. For very large events like those expected on the San Andreas fault zone or the Cascadia subduction zone the warning time could be much longer because the affected area is much larger. ShakeAlert can give enough time to slow and stop trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

System Goal

The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications by 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

Current Status

The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” test users in California since January of 2012 and in the Pacific Northwest since February of 2015.

In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California. This “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

Authorities
The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

For More Information

Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
rdegroot@usgs.gov
626-583-7225

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