Rupture propagation and damage distribution for the MW 6.3 April 6, 2009 L'Aquila earthquake

Abstract

We present rupture details of the Mw6.3 April 6, 2009 L’Aquila earthquake derived by back-projecting teleseismic P waves from a virtual seismic array. The technique that we use has previously been applied to large magnitude earthquakes, but here we report the first application to a moderate size earthquake, showing that it is possible to image teleseismically the finiteness of the source. We used waveforms from about 60 broadband seismic stations from the Incorporated Research Institutions for Seismology (IRIS) data center. The traces were aligned and normalized by using a multi-channel cross-correlation algorithm. We evaluated the array response function and used the 4th root staking in our analysis. We found that the L’Aquila earthquake ruptured toward the east and that it had two different pulses about 4 s and 18 s after the origin time. The rupture moved with a velocity of about 2 km/s. These results are in good agreement with the results obtained using satellite data and with the ones obtained by INGV geodesists. They are also consistent with the INGV earthquake survey. The major damage was also a located east of the epicenter and the specific distribution of damage is in agreement with the energy bursts detected in this paper. The back-projection technique is potentially very fast and it is possible to obtain an image of the rupture process within 20-30 minutes of the origin time. This information can be important to governmental agencies in order to guide emergency response and rescue together with other traditional methods such us ShakeMap.