Rapid kinematic finite-fault inversion for an Mw 7+ scenario earthquake in the Marmara Sea: An uncertainty study

Friday, 18 December 2015: 14:40
305 (Moscone South)
Faqi Diao1,2, Rongjiang Wang2, Hideo Aochi3, Thomas R Walter2, Yong Zhang4, Yong Zheng5 and Xiong Xiong5, (1)Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan, China, (2)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, (3)BRGM, Orleans, France, (4)Peking University, Beijing, China, (5)Institute of Geodesy & Geophysics, Hubei, China
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 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, a scenario earthquake on the main Marmara fault is simulated through dynamic modeling based on a 3D 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 1D earth structure models. The results indicate that, by using certain a-priori 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 a-priori 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.