Rapid kinematic finite-fault inversion for anM_w7+ scenario earthquake in the Marmara Sea: an uncertainty study

Abstract

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 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.

Aseismic slip and seismogenic coupling in the Marmara Sea: What can we learn from onland geodesy?

“…Ever since, GPS surveys were intensified along the continental part of the fault and, supported by the increasing quantity of data, numerous studies focused on the quantification of postseismic deformations following the Izmit and Düzce earthquakes [ Ergintav et al , ; Bürgmann et al , ; Hearn et al , ]. Even if numerous studies have investigated strain accumulation in the Marmara Sea [ McClusky et al , ; Ergintav et al , ; Diao et al , ], geodetic measurements in the western region of Istanbul remain sparse. Because of difficult field conditions, no systematic coverage have yet been performed along the shoreline of the TS and CeS, and inland, between Marmara and Black seas shorelines (Figure b).…”

Accounting for uncertain fault geometry in earthquake source inversions – I: theory and simplified application

“…The impact of this prior choice is rarely investigated, yet, a small change can affect the Green's functions, which will, in turn, distort the link between the data space and the parameters and lead to potentially very different source models (e.g. Simons et al 2002;Beresnev 2003;Hartzell et al 2007;Razafindrakoto & Mai 2014;Diao et al 2016).…”

Accounting for uncertain fault geometry in earthquake source inversions – II: application to the Mw 6.2 Amatrice earthquake, central Italy

“…Uncertainties related to these approximations will affect the calculated response of the Earth and lead to different source models (e.g. Simons et al 2002;Beresnev 2003;Hartzell et al 2007;Dettmer et al 2014;Diao et al 2016;Ragon et al 2018). These so-called epistemic uncertainties can be many orders of magnitude greater than observational uncertainties for large earthquakes (Ragon et al 2018).…”