From The University of Arizona: “Researchers home in on Thera volcano eruption date”

From The University of Arizona

May 2, 2022 [Just now in social media.]

Media contact
Mikayla Mace Kelley
Science Writer, University Communications

Researcher contact
Charlotte Pearson
Laboratory of Tree-Ring Research

Tree-ring, ice core and volcano experts teamed up to identify one of the most climatically impactful volcanic eruptions in 4,000 years – Aniakchak II. In the process, they narrowed down potential dates for the Thera volcano eruption.

The volcanic craters of Aniakchak II (left) and Thera (right). Helga Weber/University of Bern [Universität Bern](CH)

A University of Arizona tree-ring expert is closer than ever to pinning down the date of the infamous Thera volcano eruption – a goal she has pursued for decades.

Charlotte Pearson, an associate professor in the Laboratory of Tree-Ring Research, is lead author of a new paper in PNAS Nexus that combines a mosaic of techniques to confirm the source of a volcanic eruption in 1628 B.C. While the eruption was previously thought to be Thera on the Greek island of Santorini, Pearson and her colleagues found instead that it was Alaskan volcano Aniakchak II.

The finding helps researchers narrow down when the actual Thera eruption took place.

Thera’s massive eruption, known to have occurred sometime before 1500 B.C., buried the Minoan town of Akrotiri in more than 130 feet of debris. But the exact date of the eruption, along with its impact on climate, have been debated for decades.

If a volcanic eruption is large enough, it can eject sulfur and debris called tephra into the stratosphere, where both can be circulated to places very far away. The sulfur dioxide from the eruption that makes it into the upper atmosphere reflects heat from the sun and causes temperatures around the world to drop. The climatic shift is reflected in trees, which show reduced growth or frost rings that effectively mark the year in which the eruption occurred.

The sulfur and tephra can also rain down on Earth’s poles, where they are preserved in layers of ice. When ice cores are analyzed, the amount of sulfate in them can also be used to estimate the likely impact of an eruption on climate. High-sulfate eruptions have greater potential to cause short-term shifts in climate. At the same time, the ice cores’ tephra, which has a unique geochemical fingerprint, can be used to link the sulfur in the ice to an exact volcanic source.

The dark ring in this cutting of California Bristlecone pine marks an area of frost damage caused by the rapidly cooling climate due to the large amount of sulfate released by what scientists confirm was Aniakchak II rather than Thera. This marker (1627 BC) first connected tree grow and volcanic climate response, and ignited the work to synchronize tree rings and ice cores. Credit: Charlotte Pearson.

Pearson and her collaborators – which included Michael Sigl of the University of Bern and an international team of geochemists, ice core experts and tephra chronologists – aligned data from tree rings and from ice cores in Antarctica and Greenland to create a comprehensive record of volcanic eruptions across the period when Thera must have occurred – 1680 to 1500 B.C. They used sulfate and tephra evidence to rule out several of the events as potential Thera dates and used high-resolution techniques to geochemically confirm through the ice cores that the eruption recorded in1628 B.C. was Aniakchak II.

The exact Thera eruption date remains unconfirmed, but the team has narrowed it down to just a handful of possibilities: 1611 B.C., 1562-1555 B.C. and 1538 B.C.

“One of these is Thera,” Pearson said. “We just can’t confirm which one yet, but at least we now know exactly where to look. The challenge with Thera is that there’s always been this discrepancy between multiple lines of dating evidence. Now that we know what the possible dates are, this evidence can be re-evaluated, but we still need a geochemical fingerprint to clinch it.”

See the full article here .

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As of 2019, the The University of Arizona enrolled 45,918 students in 19 separate colleges/schools, including The University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). The University of Arizona is one of three universities governed by the Arizona Board of Regents. The university is part of the Association of American Universities and is the only member from Arizona, and also part of the Universities Research Association . The university is classified among “R1: Doctoral Universities – Very High Research Activity”.

Known as the Arizona Wildcats (often shortened to “Cats”), The University of Arizona’s intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. The University of Arizona athletes have won national titles in several sports, most notably men’s basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.

After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew. The Arizona Territory’s “Thieving Thirteenth” Legislature approved The University of Arizona in 1885 and selected the city of Tucson to receive the appropriation to build the university. Tucson hoped to receive the appropriation for the territory’s mental hospital, which carried a $100,000 allocation instead of the $25,000 allotted to the territory’s only university Arizona State University was also chartered in 1885, but it was created as Arizona’s normal school, and not a university). Flooding on the Salt River delayed Tucson’s legislators, and by the time they reached Prescott, back-room deals allocating the most desirable territorial institutions had been made. Tucson was largely disappointed with receiving what was viewed as an inferior prize.

With no parties willing to provide land for the new institution, the citizens of Tucson prepared to return the money to the Territorial Legislature until two gamblers and a saloon keeper decided to donate the land to build the school. Construction of Old Main, the first building on campus, began on October 27, 1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no high schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation.


The University of Arizona is classified among “R1: Doctoral Universities – Very high research activity”. UArizona is the fourth most awarded public university by National Aeronautics and Space Administration for research. The University of Arizona was awarded over $325 million for its Lunar and Planetary Laboratory (LPL) to lead NASA’s 2007–08 mission to Mars to explore the Martian Arctic, and $800 million for its OSIRIS-REx mission, the first in U.S. history to sample an asteroid.

National Aeronautics Space Agency OSIRIS-REx Spacecraft.

The LPL’s work in the Cassini spacecraft orbit around Saturn is larger than any other university globally.

National Aeronautics and Space Administration/European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ASI Italian Space Agency [Agenzia Spaziale Italiana](IT) Cassini Spacecraft.

The University of Arizona laboratory designed and operated the atmospheric radiation investigations and imaging on the probe. The University of Arizona operates the HiRISE camera, a part of the Mars Reconnaissance Orbiter.

U Arizona NASA Mars Reconnaisance HiRISE Camera.

NASA Mars Reconnaissance Orbiter.

While using the HiRISE camera in 2011, University of Arizona alumnus Lujendra Ojha and his team discovered proof of liquid water on the surface of Mars—a discovery confirmed by NASA in 2015. The University of Arizona receives more NASA grants annually than the next nine top NASA/JPL-Caltech-funded universities combined. As of March 2016, The University of Arizona’s Lunar and Planetary Laboratory is actively involved in ten spacecraft missions: Cassini VIMS; Grail; the HiRISE camera orbiting Mars; the Juno mission orbiting Jupiter; Lunar Reconnaissance Orbiter (LRO); Maven, which will explore Mars’ upper atmosphere and interactions with the sun; Solar Probe Plus, a historic mission into the Sun’s atmosphere for the first time; Rosetta’s VIRTIS; WISE; and OSIRIS-REx, the first U.S. sample-return mission to a near-earth asteroid, which launched on September 8, 2016.

NASA – GRAIL Flying in Formation (Artist’s Concept). Credit: NASA.
National Aeronautics Space Agency Juno at Jupiter.

NASA/Lunar Reconnaissance Orbiter.


NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker. The Johns Hopkins University Applied Physics Lab.
National Aeronautics and Space Administration Wise/NEOWISE Telescope.

The University of Arizona students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UArizona is among the top 25 producers of Fulbright awards in the U.S.

The University of Arizona is a member of the Association of Universities for Research in Astronomy , a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory just outside Tucson.

National Science Foundation NOIRLab National Optical Astronomy Observatory Kitt Peak National Observatory on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft). annotated.

Led by Roger Angel, researchers in the Steward Observatory Mirror Lab at The University of Arizona are working in concert to build the world’s most advanced telescope. Known as the Giant Magellan Telescope (CL), it will produce images 10 times sharper than those from the Earth-orbiting Hubble Telescope.

GMT Giant Magellan Telescope(CL) 21 meters, to be at the Carnegie Institution for Science’s NOIRLab NOAO Las Campanas Observatory(CL), some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.

The telescope is set to be completed in 2021. GMT will ultimately cost $1 billion. Researchers from at least nine institutions are working to secure the funding for the project. The telescope will include seven 18-ton mirrors capable of providing clear images of volcanoes and riverbeds on Mars and mountains on the moon at a rate 40 times faster than the world’s current large telescopes. The mirrors of the Giant Magellan Telescope will be built at The University of Arizona and transported to a permanent mountaintop site in the Chilean Andes where the telescope will be constructed.

Reaching Mars in March 2006, the Mars Reconnaissance Orbiter contained the HiRISE camera, with Principal Investigator Alfred McEwen as the lead on the project. This National Aeronautics and Space Agency mission to Mars carrying the UArizona-designed camera is capturing the highest-resolution images of the planet ever seen. The journey of the orbiter was 300 million miles. In August 2007, The University of Arizona, under the charge of Scientist Peter Smith, led the Phoenix Mars Mission, the first mission completely controlled by a university. Reaching the planet’s surface in May 2008, the mission’s purpose was to improve knowledge of the Martian Arctic. The Arizona Radio Observatory , a part of The University of Arizona Department of Astronomy Steward Observatory , operates the Submillimeter Telescope on Mount Graham.

University of Arizona Radio Observatory at NOAO Kitt Peak National Observatory, AZ USA, U Arizona Department of Astronomy and Steward Observatory at altitude 2,096 m (6,877 ft).

Kitt Peak National Observatory in the Arizona-Sonoran Desert 88 kilometers 55 mi west-southwest of Tucson, Arizona in the Quinlan Mountains of the Tohono O’odham Nation, altitude 2,096 m (6,877 ft)

The National Science Foundation funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as “CyVerse”, the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines.

In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona, north of Tucson, effective July 1. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.

U Arizona mirror lab-Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

University of Arizona’s Biosphere 2, located in the Sonoran desert. An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why The University of Arizona is a university unlike any other.

University of Arizona Landscape Evolution Observatory at Biosphere 2.