19. Research into seismological and tectonic source properties of tsunamigenic earthquakes

In the past two decades, more than 100 earthquakes have generated measurable tsunami wave heights. The effects from the vast majority of these earthquakes have been minor. But a few, such as the Andaman-Sumatra earthquake of 2004 and the Solomons earthquake of 2007, are responsible for inflicting horrific mortality and enormous coastal devastation at local as well as transoceanic distances from the epicenter. The USGS is responsible for the rapid detection and location of earthquakes and the immediate transmittal of this information to agencies responsible for issuing appropriate levels of tsunami warning. The focus of this Mendenhall research opportunity is to use the resources at the USGS to identify characteristics of tsunamigenic earthquakes, thereby providing a foundation for enhancing the reliability, the accuracy and the timeliness of tsunami warnings as well as long-term hazard assessment.

Research under this opportunity will emphasize using seismological seismic waveform data to: (1) infer properties of known tsunamigenic earthquakes, (2) use these properties to evaluate various mechanisms and conditions that have been proposed for earthquake-generated tsunamis, and (3) identify anomalies that can indicate zones that are currently quiet but capable of generating tsunamis. Of particular interest is a class of tsunamigenic events known as slow earthquakes which are associated with abnormally long source durations and anomalously low radiated seismic energy. These slow earthquakes are problematic from the standpoint of early identification of tsunami threat since they can have magnitudes below conventional thresholds. Methods to validate and refine such mechanisms may include but are not limited to delineating and correlating the seismological behavior (such as temporal and spatial patterns of seismicity and source parameters like moment, radiated energy, and associated stresses) with the geophysical and geological environment of tsunami earthquakes. Research under this opportunity may evolve into collaborative studies using global plate motions, marine geology and geophysics, tsunami-generation and hydrodynamic models and subduction science.

Tsunamis have killed hundreds of Americans and caused hundreds of millions of dollars of damage in the United States. As increased population density along coastlines worldwide has increased the vulnerability of peoples and habitations, future tsunamis will inevitably impact Hawaii, Alaska, the Pacific Northwest, the Caribbean and other U.S. interests in the Pacific Basin. The USGS has been expanding its capabilities to parameterize the earthquake process, to assess the potential impact of large earthquakes, and to expeditiously disseminate the resulting information to relevant agencies. The result of this effort is a new state-of-the-art earthquake processing system (Hydra) and a number of new product tools (for example, centroid moment tensors, finite fault analysis, and global ShakeMaps) that allow for rapid analysis of earthquake activity and a quick understanding of the dominant characteristics of an earthquake source. Missing from this enhanced earthquake analysis package, however, are tools focused on tsunamigenic sources (for example, energy magnitude computations, determination of the geologic and geophysical environment of tsunami earthquakes). Incorporating characteristics that have been identified as tsunamigenic into a comprehensive package of USGS data services will enhance the ability of Federal and international agencies to formulate a credible and appropriate level of response, both for long term hazard planning as well as for real-time warning.

Proposed Duty Station: Golden, CO

Areas of Ph.D.: Geology, geophysics, seismology, computer science

Qualifications: Applicants must meet one of the following qualifications: Research Geologist, Research Geophysicist, Computer Scientist

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Research Advisor(s): George Choy, (303) 273-8424, choy@usgs.gov; Stephen Kirby, (650) 329-4847, skirby@usgs.gov; Eric Geist, (650) 329-5457, egeist@usgs.gov

Human Resources Office contact: Kathleen Scheich, (303) 236-9581, kscheich@usgs.gov

Summary of Opportunities