This paper presents the calibration of Omori’s aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock tha...This paper presents the calibration of Omori’s aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock that exceeds a specific magnitude threshold within a time interval after the mainshock. Critical decisions on the post-earthquake safety of structures directly depend on the aftershock hazard estimated using the occurrence model. It is customary to calibrate models in a region-specific manner. These models depend on rate parameters(a, b, c and p) related to the seismicity characteristics of the investigated region. In this study, the available well-recorded aftershock sequences for a set of Mw ≥ 5.9 mainshock events that were observed in Turkey until 2012 are considered to develop the aftershock occurrence model. Mean estimates of the model parameters identified for Turkey are a =-1.90, b = 1.11, c = 0.05 and p = 1.20. Based on the developed model, aftershock likelihoods are computed for a range of different time intervals and mainshock magnitudes. Also, the sensitivity of aftershock probabilities to the model parameters is investigated. Aftershock occurrence probabilities estimated using the model are expected to be useful for post-earthquake safety evaluations in Turkey.展开更多
We obtained a catalog of early aftershocks of the 2013 Lushan earthquake by examining waveform from a nearby station MDS which is 30.2 km far away from the epicenter, and then we analyzed the relation between aftersho...We obtained a catalog of early aftershocks of the 2013 Lushan earthquake by examining waveform from a nearby station MDS which is 30.2 km far away from the epicenter, and then we analyzed the relation between aftershock rate and time. We used time-window ratio method to identify aftershocks from continuous waveform data and compare the result with the catalog provided by China Earthquake Networks Center （CENC）. As expected, a significant amount of earthquakes is missing in CENC catalog in the 24 h after the main shock. Moreover, we observed a steady seismicity rate of aftershocks nearly in the first 10,000 s before an obvious power-law decay of aftershock activity. We consider this distinct early stage which does not fit the Omori law with a constant p （p - 1） value as early aftershock deficiency （EAD）, as proposed by previous studies. Our study suggests that the main shock rupture process is different from aftershocks＇ processes, and EAD can vary in different cases as compared to earthquakes of strike-slip mechanism in California.展开更多
We use an efficient earthquake simulator that incorporates rate-state constitutive properties and uses boundary element method to discretize the fault surfaces, to generate the synthetic earthquakes in the fault syste...We use an efficient earthquake simulator that incorporates rate-state constitutive properties and uses boundary element method to discretize the fault surfaces, to generate the synthetic earthquakes in the fault system. Rate-and-state seismicity equation is subsequently employed to calculate the seismicity rate in a region of interest using the Coulomb stress transfer from the main shocks in the fault system. The Coulomb stress transfer is obtained by resolving the induced stresses due to the fault patch slips onto the optimal-oriented fault planes. The example results show that immediately after a main shock the aftershocks are concentrated in the vicinity of the rupture area due to positive stress transfers and then dis- perse away into the surrounding region toward the back- ground rate distribution. The number of aftershocks near the rupture region is found to decay with time as Omori aftershock decay law predicts. The example results dem- onstrate that the rate-and-state fault system earthquakesimulator and the seismicity equations based on the rate- state friction nucleation of earthquake are well posited to characterize the aftershock distribution in regional assess- ments of earthquake probabilities.展开更多
基金Supported by:Scientific and Technological Research Council of Turkey(TUBITAK)with Grant No.213M454
文摘This paper presents the calibration of Omori’s aftershock occurrence rate model for Turkey and the resulting likelihoods. Aftershock occurrence rate models are used for estimating the probability of an aftershock that exceeds a specific magnitude threshold within a time interval after the mainshock. Critical decisions on the post-earthquake safety of structures directly depend on the aftershock hazard estimated using the occurrence model. It is customary to calibrate models in a region-specific manner. These models depend on rate parameters(a, b, c and p) related to the seismicity characteristics of the investigated region. In this study, the available well-recorded aftershock sequences for a set of Mw ≥ 5.9 mainshock events that were observed in Turkey until 2012 are considered to develop the aftershock occurrence model. Mean estimates of the model parameters identified for Turkey are a =-1.90, b = 1.11, c = 0.05 and p = 1.20. Based on the developed model, aftershock likelihoods are computed for a range of different time intervals and mainshock magnitudes. Also, the sensitivity of aftershock probabilities to the model parameters is investigated. Aftershock occurrence probabilities estimated using the model are expected to be useful for post-earthquake safety evaluations in Turkey.
基金supported by the State Key Laboratory of Geodesy and Earth’s Dynamics,Institute of Geodesy and Geophysicsthe Chinese Academy of Sciences through grant number SKLGED2013-7-1-Z
文摘We obtained a catalog of early aftershocks of the 2013 Lushan earthquake by examining waveform from a nearby station MDS which is 30.2 km far away from the epicenter, and then we analyzed the relation between aftershock rate and time. We used time-window ratio method to identify aftershocks from continuous waveform data and compare the result with the catalog provided by China Earthquake Networks Center （CENC）. As expected, a significant amount of earthquakes is missing in CENC catalog in the 24 h after the main shock. Moreover, we observed a steady seismicity rate of aftershocks nearly in the first 10,000 s before an obvious power-law decay of aftershock activity. We consider this distinct early stage which does not fit the Omori law with a constant p （p - 1） value as early aftershock deficiency （EAD）, as proposed by previous studies. Our study suggests that the main shock rupture process is different from aftershocks＇ processes, and EAD can vary in different cases as compared to earthquakes of strike-slip mechanism in California.
基金supported by the NSF Frontiers in Earth-System Dynamics(EAR-1135455)the Extreme Science and Engineering Discovery Environment(XSEDE),which is supported by National Natural Science Foundation grant No.OCI-1053575the Blue Waters sustained-petascale computing project,which is supported by the National Natural Science Foundation(award No.OCI 07-25070)and the state of Illinois
文摘We use an efficient earthquake simulator that incorporates rate-state constitutive properties and uses boundary element method to discretize the fault surfaces, to generate the synthetic earthquakes in the fault system. Rate-and-state seismicity equation is subsequently employed to calculate the seismicity rate in a region of interest using the Coulomb stress transfer from the main shocks in the fault system. The Coulomb stress transfer is obtained by resolving the induced stresses due to the fault patch slips onto the optimal-oriented fault planes. The example results show that immediately after a main shock the aftershocks are concentrated in the vicinity of the rupture area due to positive stress transfers and then dis- perse away into the surrounding region toward the back- ground rate distribution. The number of aftershocks near the rupture region is found to decay with time as Omori aftershock decay law predicts. The example results dem- onstrate that the rate-and-state fault system earthquakesimulator and the seismicity equations based on the rate- state friction nucleation of earthquake are well posited to characterize the aftershock distribution in regional assess- ments of earthquake probabilities.
