Rapid kinematic finite-fault inversion for an M w 7+ scenario earthquake in the Marmara Sea: an uncertainty study
Résumé
During the 20th century, a series of devastating earthquakes occurred along the North Anatolian
Fault. These generally propagated westwards, such that the main fault segment beneath the
Marmara Sea appears as a seismic gap. For the nearby megacity Istanbul, rapid seismic hazard
assessment is currently of great importance. A key issue is how a strong earthquake in the
Marmara Sea can be characterized reliably and rapidly using the seismic network currently
operating in this region. In order to investigate this issue, several scenario earthquakes on the
main Marmara fault are simulated through dynamic modelling based on a 3-D structure model.
The synthetic datasets are then used to reconstruct the source processes of the causal events
with a recently developed iterative deconvolution and stacking method based on simplified 1-D
Earth structure models. The results indicate that, by using certain apriori information about
the fault geometry and focal mechanism, the tempo-spatial slip patterns of the input scenarios
can be well resolved. If reasonable uncertainties are considered for the apriori information,
the key source parameters, such as moment magnitude, fault size and slip centroid, can still
be estimated reliably, while the detailed tempo-spatial rupture pattern may reveal significant
variations. To reduce the effect induced by employing the inaccurate event location and focal
mechanism, a new approach for absolute source imaging is proposed and tested. We also
investigate the performance of the new source imaging tool for near real-time source inversion
under the current network configuration in the Marmara Sea region. The results obtained are
meaningful particularly for developing the rapid earthquake response system for the megacity
Istanbul