Eos, Transactions American Geophysical Union

How earthquake properties vary with depth



A new study shows systematically how seismic properties vary with depth. Lay et al. analyzed recent large and great earthquakes, including the 2004 Sumatra-Andaman (Mw 9.2), 2010 Chile (Mw 8.8), and 2011 Tohoku (Mw 9.0) earthquakes. The researchers define four domains of seismogenic behavior along megathrust faults according to depth. In domain A, the shallowest, reaching to about 15 kilometers below sea level, large tsunami- generating earthquakes can occur. In domain B, extending from about 15- to 35-kilometers depth, great earthquake events with large slip but diffuse short-period energy occur. In domain C, from 35- to 55-kilometers depth, smaller isolated megathrust patches rupture, producing bursts of coherent short-period energy in both great ruptures and in moderatesized events. In domain D, which extends from about 30- to 45-kilometers depth in subduction zones where relatively young ocean lithosphere is being underthrust with shallow plate dip, low-frequency earthquakes, seismic tremor, and slow slip events occur. Below this zone, stabile sliding or ductile doma takes place. (Journal of Geophysical Research-Solid Earth, doi:10.1029/2011JB009133, 2012)