Measuring Earthquakes - A New Robust Method To Estimate Kinematic Earthquake Source Parameters

Rapid and automatic methods to determine earthquake source parameters have become standard in modern seismology. Currently, most such methods are based on point source (i.e. moment tensor) approximations of the earthquake rupture, but for some applications (especially in the scope of rapid hazard assessment and tsunami early warning) these are not sufficient. The aim of KINHERD is to investigate the possibilities to rapidly determine, based on teleseismic and regional recordings, not only point source but also kinematic earthquake source parameters. The main challenges we were facing, were how to identify and prevent ambiguities in the retrieved parameters and how to properly quantify errors on the results. These requirements essentially call for a very efficient forward modelling technique. Our efforts have lead us to devolop a set of tools to calculate synthetic seismograms for arbitrary extended earthquake source models based on pre-calculated Green's functions. These tools provide a flexible framework to implement various strategies to determine earthquake source properties on local, regional, and global scales. My primary focus in this presentation will be to show how the parameters of a simple kinematic earthquake model are retrieved for the recent Mw 6.3 L'Aquila earthquake by fitting teleseismic body-wave spectra. We find a fault extension consistent with aftershock distributions and a predominantly unilateral rupture propagation from north-east to south-west. As a contrasting example and to demonstrate the broad applicability of our new tools, I will discuss a partial moment-tensor analysis we implemented to study an Mw 0.6 micro-earthquake which occurred beneath Hamburg in April 2009.

Contact: sebastian.heimann@zmaw.de