Robust Earthquake Source Scaling and Seismic Efficiency for Intermediate Depth and Deep Earthquakes at Global and Regional Scales

Earthquakes pose a significant hazard to communities worldwide. One type of earthquakes that are generally known as deep earthquakes, mostly occur along subduction zones in Japan, Alaska, Cascadia, and South America to name a few. Even though they represent about 25% of the total number of earthquakes worldwide, as of yet, we do not clearly understand the mechanism that allow this earthquakes to occur. In the proposed research we will study two of the active regions in terms of deep earthquakes, México and Chile, combining both global observations and available regional observations from the national seismic networks of the respective countries. We will determine not only the magnitude of the events but also the complete energy budgets that can describe the way in which these earthquakes start and grow, and ultimately constrain the driving mechanism. Our observations and analysis will provide fundamental parameters that may help laboratory experiments compare and extrapolate their observations to a realistic Earth, better predict the ground motions of future large deep earthquakes in Chile and Mexico and mitigate seismic hazard in other regions as well.

Recent work on deep and intermediate-depth earthquakes has raised new questions about possible mechanisms involved in these earthquakes [Prieto et al., 2013; Zhan et al 2014; Meng et al, 2014]. We propose to extend the determination of the complete earthquake energy budget at global scales, using broadband seismic stations at teleseismic distances. Because of the limited ability of retrieving high frequencies at these distances, only earthquakes with M>5.5 are analyzed [Poli and Prieto, 2014]. Therefore, we will include at least two areas with records of intermediate-depth and deep earthquakes at regional scales (e.g., Mexico, Chile) that will allow for accurate analysis of M>3.5. For an accurate analysis of the earthquake source process, it is necessary to determine both static source parameters - including magnitude, duration and rupture size - and dynamic parameters like radiated seismic energy and rupture velocity. With these parameters it will be possible to determine the energy partitioning during earthquake rupture. We hope to be able to relate our observed variations with geodynamical properties of the associated subducted slabs and better constrain the physical mechanism involved in deep earthquake rupture.