GHOSH EARTHQUAKE SEISMOLOGY LAB
We work on earthquake seismology
WHAT WE DO
Slow And Fast Earthquakes
We study earthquakes using mainly seismology. We record and analyze seismograms (records of ground vibrations produced by earthquakes) to better understand the physics of earthquakes and the processes that control them. We work on large, damaging subduction plate boundary earthquakes to tiny local earthquakes. We are interested in better characterizing and understanding a broad spectrum of slip that we observe. In particular, we have pioneered work on slow earthquakes, a relatively new branch of earthquake science. Slow earthquakes are critical to understanding fault slip dynamics, earthquake nucleation and estimating earthquake hazard.
We develop new techniques to detect, locate and track slow earthquakes in high resolution. Typically, we conceive and design seismic experiments in an attempt to answer scientifically interesting questions, go to the field to install seismic stations, record new seismic data, analyze them, produce results and interpret them to come up with an answer. We specialize in seismic array techniques in various space and time scales. Our approach provides members of this group opportunity to do interesting science with options and flexibility to travel to distant places, explore nature and/or work in an office setting.
Tremor signals during fluid injection are generated by fault slip
Seismic tremor signals, also known as long-period, long-duration signals, have been reported in several locations where fluid injection for enhanced oil and gas exploration is taking place. However, the origin of these signals remains poorly constrained. We studied seismic tremor signals in Wellington Field, Kansas, using a seismic array during a carbon dioxide injection program. We show that these signals are generated below the surface during the time of carbon dioxide injection. They have a distinct spectral signature, similar to those observed in glacial and volcanic environments. The tremor sources are located near the injection site and aligned with preexisting faults. Modeling results imply that such tremors are generated by frictional slip on fault. These observations may reveal an important deformation mode, which is useful for studying associated stress, seismicity, and triggering, as well as for tracking fault activities during injection operations of all fluids, including supercritical carbon dioxide.