San Francisco, April 11, 2012 -- David Shelly has quickly established himself as world leader in observational seismology, having already made a dramatic impact on the field of seismology through his pioneering work to detect and locate deep tectonic tremor.
For his work, the Seismological Society of America will honor Shelly with its Charles. F. Richter Early Career Award, which honors outstanding contributions to the goals of the Society by a member early in her or his career.
While a graduate student at Stanford University, Shelly spent one summer in Japan at the University of Tokyo, where he studied a new class of low frequency earthquakes (LFE), which are tiny earthquakes observed almost exclusively during periods of deep tremor. In a groundbreaking paper published by the journal Nature, he described that the LFEs represented shear slip on the plate interface. In a subsequent paper, also published by Nature, he demonstrated that deep tremor consists of a swarm of LFEs, challenging the prevailing theory that suggested tremor was the signature of fluid movement.
As a Mendenhall Postdoctoral Fellow at the U.S. Geological Survey, Shelly focused his research on tremor under the San Andreas Fault, identifying a streak of low frequency earthquakes on the deep extension of the fault and demonstrating that the recurrence of LFEs changes with time.
His more recent papers have concentrated on the locations, physical mechanism, and temporal patterns of the tremor, which may reveal new information about the behavior of faults.
At the upcoming SSA annual meeting, Shelly will discuss a new study that looks at recent earthquake swarms deep below Mammoth Mountain in California that offer a unique chance to see how volcanic processes operate in the Earth's lower crust. He and his colleague David Hill of the U.S. Geological Survey collected and analyzed swarms of brittle-failure earthquake events underneath Mammoth Mountain—which sits on the edge of the volcanic Long Valley Caldera—from 2006 to 2009. Brittle-failure quakes are relatively rare in this deeply buried rock, since it's typically more soft and flexible under the high temperatures and pressures of the lower crust. During the best-recorded swarm in 2009, Shelly found that the quakes quickly moved upward and were relatively short-lived. Given this pattern, the researchers say the cause of the quakes may have been pressure from carbon dioxide-rich fluids released from deep magma, which triggered slip along preexisting faults.
Shelly earned a bachelor's in mathematics and physics from Whitman College in Washington and a Ph.D. in geophysics from Stanford University. He is currently a Research Seismologist at the U.S. Geological Survey and serves as part of the Volcano Science Center.
SSA is an international scientific society devoted to the advancement of seismology and its applications in understanding and mitigating earthquake hazards and in imaging the structure of the earth. Founded in 1906 in San Francisco, the Society now has members throughout the world representing a variety of technical interests: seismologists and other geophysicists, geologists, engineers, insurers, and policy-makers in preparedness and safety.