Spatio‐temporal source characteristics of the 26 December 2004 Sumatra earthquake as imaged by teleseismic broadband arrays

We test the capability of broadband arrays at teleseismic distances to image the spatio‐temporal characteristics of the seismic energy release during the Dec 26, 2004 Sumatra earthquake at early observation times. Using a non‐plane‐wave array location technique previously reported values for rupture length (about 1150 km), duration (about 480 s), and average rupture velocity (2.4–2.7 km/s) are confirmed. Three dominant energy releases are identified: one near the hypocenter, a second at 6°N 94°E about 130 s later and a third one after 300 s at 9°N 92–93°E. The spatio‐temporal distribution of the radiated seismic energy in the source region is calculated from the stacked broadband recordings of two arrays in Germany and Japan and results in rough estimates of the total seismic energy of 0.55 · 1018 Nm (GRSN) and 1.53 · 1018 Nm (FNET) respectively. Changes in the relative ratio of energy as function of spatio‐temporal location indicate a rotation of the focal mechanism during the rupture process.