Modelling earthquake rates and associated uncertainties in the Marmara Region, Turkey

Abstract

Abstract. Modelling the seismic potential of active faults and the associated epistemic uncertainty is a fundamental step of probabilistic seismic hazard assessment (PSHA). We use SHERIFS (Seismic Hazard and Earthquake Rate In Fault Systems), an open-source code allowing us to build hazard models including earthquake ruptures involving several faults, to model the seismicity rates on the North Anatolian Fault (NAF) system in the Marmara Region. Through an iterative approach, SHERIFS converts the slip rate on the faults into earthquake rates that follow a magnitude frequency distribution (MFD) defined at the fault system level, allowing us to model complex multi-fault ruptures and off-fault seismicity while exploring the underlying epistemic uncertainties. In a logic tree, we explore uncertainties concerning the locking state of the NAF in the Sea of Marmara, the maximum possible rupture in the system, the shape of the MFD and the ratio of off-fault seismicity. The branches of the logic tree are weighted according to the match between the modelled earthquake rate and the earthquake rates calculated from the local data, earthquake catalogue and palaeoseismicity. In addition, we use the result of the physics-based earthquake simulator RSQSim to inform the logic tree and increase the weight on the hypotheses that are compatible with the result of the simulator. Using both the local data and the simulator to weight the logic tree branches, we are able to reduce the uncertainties affecting the earthquake rates in the Marmara Region. The weighted logic tree of models built in this study will be used in a following article to calculate the probability of collapse of a building in Istanbul.

Seismogenic potential and tsunami threat of the strike-slip Carboneras Fault in the Western Mediterranean from physics-based earthquake simulations

“…The inter-event time for these magnitudes is around 2000 -6000 years (Figure 4). From a probabilistic point of view, these models have shown in the Probabilistic Seismic Hazard Analyses (PSHA) a great potential to estimate recurrence periods and inter-event times for large earthquakes, which are poorly represented in the instrumental seismic catalogues (Chartier et al, 2021;Herrero-Barbero et al, 2021;Console et al, 2017); being one of the key pieces in the current development of seismic forecast models (Dieterich and Richards-Dinger, 2010;Field, 2019;Field et al, 2014;Shaw et al, 2018). The implementation of these methodologies in the Probabilistic Tsunami Hazard Analyses (PTHA) is a logical and necessary step.…”

“…The result is a long synthetic earthquake catalogue including a comprehensive and detailed record of complex earthquake ruptures with heterogeneous slip. Recent results obtained using the RSQSim code are promising in relation to potential practical applicability (Chartier et al, 2021;Herrero-Barbero et al, 2021;Howarth et al, 2021;Shaw et al, 2018).…”

Fuzzy Interpolation Curve Modelling of Earthquake Magnitude Data

“…Many research has been done about earthquakes such as [20][21][22][23]. Also, research that focuses on solving uncertainty problems had been discussed [24][25][26][27] and research that involves spline function as spline interpolation can be referred to by [28].…”

Impact of Variable Fault Geometries and Slip Rates on Earthquake Catalogs From Physics‐Based Simulations of a Normal Fault

“…(2021) employed RSQSim to establish a nonergodic framework for probabilistic seismic‐hazard analysis, while Chartier et al. (2021) utilized RSQSim as an auxiliary tool for weighting a logic tree that explores seismicity uncertainties in the Sea of Marmara. These papers demonstrate the utility of RSQSim and coupled with its increasing availability suggest that it will continue to have seismic hazard applications.…”

“…Shaw et al (2018) found that RSQSim simulations for the Californian fault system can replicate the seismic hazard statistics from the long-term Third Uniform California Earthquake Rupture Forecast (UCERF3; Field et al, 2014). Similarly, Milner et al (2021) employed RSQSim to establish a nonergodic framework for probabilistic seismic-hazard analysis, while Chartier et al (2021) utilized RSQSim as an auxiliary tool for weighting a logic tree that explores seismicity uncertainties in the Sea of Marmara. These papers demonstrate the utility of RSQSim and coupled with its increasing availability suggest that it will continue to have seismic hazard applications.…”