We study the seismic waves radiated by earthquakes to understand the mechanics of the earthquake process. Although we are interested in this for purely scientific reasons, it has the important benefit of enabling improved strong ground motion prediction.
We are interested in the energy radiated by earthquakes in the form of seismic waves. Although energy is a scalar quantity, it is difficult to measure because earthquake energy is broadband, with most of the energy radiated in seismic waves above the corner frequency. Our recent efforts have focused on empirical Green's function (eGf)-based measurements. We have developed an approach to determine the radiated energy from great (M > 8.5) earthquakes using other large earthquakes as eGfs.
;We developed the first "pseudo-dynamic" rupture models (Guatteri et al., 2003). Pseudo-dynamic models are kinematic models that seek to emulate the behavior of spontaneous dynamic rupture models. They provide a computationally tractable method for physics-based seismic hazard analysis. Current research is focused on including the possibility of super-shear rupture velocity in pseudo-dynamic models.
We are also collaborating with Professor German Prieto at the University of the Andes in Bogota, to study the mechanics of intermediate-dept earthquakes using observations from the Colombian National Seismic Network in the Bucaramanga "Nest". The Bucaramanga Nest represents the most intense concentration of intermediate-depth earthquakes in the world, and as such is the world's premier natural laboratory for studying intermediate-depth earthquakes, which even less well understood than shallow earthquakes.
Baltay A., G. Prieto, and G. Beroza (2010), Radiated seismic energy from coda measurements indicates no scaling in apparent stress with seismic moment, J. Geophys. Res., 115(B8), doi:10.1029/2009JB006736.
Ide, S., A. Baltay, and G. C. Beroza (2011), Shallow Dynamic Overshoot and Energetic Deep Rupture of the 2011 Mw 9.0 Tohoko-Oki Earthquake,Science, 19 May 2011:1207020,doi:10.1126/science.1207020.
Baltay, A., S. Ide, G. Prieto, and G. C. Beroza (2011), Variability in earthquakes stress drop and apparent stress, Geophys. Res. Lett., 38, L06303, doi:10.1029/2011/GL046698.