January PGS meeting
The January meeting of the Potomac Geophysical Society will be held January 15th at the Fort Myer Officers' Club in Arlington, VA in the Campaign Room.
This month's talk will be: How Deep Was That Earthquake?, by Jack Murphy, SAIC, McLean, VA.
Abstract:
Less than 100 years ago, seismologists were still actively debating whether deep earthquakes existed, and it wasn't until the 1920s that Turner in England and Wadati in Japan confirmed that some earthquakes do indeed occur at great depths below the surface of the Earth. We now know that, while the majority of earthquakes are shallow and confined to the Earth's crust, there are numerous earthquakes every year that occur at depths of hundreds of kilometers below the Earth's surface. Moreover, these deep earthquakes have played an important role in the development of our understanding of plate tectonics in that they mostly are confined to restricted zones along convergent plate boundaries, where their locations as functions of depth map out the trajectories of the descending slabs. However, despite the many improvements in computing power and analysis capability that have been introduced into earthquake location studies in recent years, it is still a challenge in many cases to accurately estimate the depth of an earthquake using commonly available seismological arrival time data. In this talk, the history of earthquake depth determination will be briefly reviewed and some recent research that has led to new approaches designed to address limitations of existing standard analysis procedures will be discussed.
Biographical Information:
Mr. Murphy is the Deputy Division Manager of the Monitoring Research Division of SAIC where he is responsible for managing research contracts with a variety of government agencies. He has had more than 40 years experience as a research seismologist and is an internationally recognized expert in the modeling and analysis of seismic signals produced by explosion and earthquake sources.
This month's talk will be: How Deep Was That Earthquake?, by Jack Murphy, SAIC, McLean, VA.
Abstract:
Less than 100 years ago, seismologists were still actively debating whether deep earthquakes existed, and it wasn't until the 1920s that Turner in England and Wadati in Japan confirmed that some earthquakes do indeed occur at great depths below the surface of the Earth. We now know that, while the majority of earthquakes are shallow and confined to the Earth's crust, there are numerous earthquakes every year that occur at depths of hundreds of kilometers below the Earth's surface. Moreover, these deep earthquakes have played an important role in the development of our understanding of plate tectonics in that they mostly are confined to restricted zones along convergent plate boundaries, where their locations as functions of depth map out the trajectories of the descending slabs. However, despite the many improvements in computing power and analysis capability that have been introduced into earthquake location studies in recent years, it is still a challenge in many cases to accurately estimate the depth of an earthquake using commonly available seismological arrival time data. In this talk, the history of earthquake depth determination will be briefly reviewed and some recent research that has led to new approaches designed to address limitations of existing standard analysis procedures will be discussed.
Biographical Information:
Mr. Murphy is the Deputy Division Manager of the Monitoring Research Division of SAIC where he is responsible for managing research contracts with a variety of government agencies. He has had more than 40 years experience as a research seismologist and is an internationally recognized expert in the modeling and analysis of seismic signals produced by explosion and earthquake sources.
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