Objective The occurrence of the devastating Wenchuan earthquake not only caused huge economic loss and deaths but also raised a question whether or not it would trigger any destructive earthquakes on its neighboring s...Objective The occurrence of the devastating Wenchuan earthquake not only caused huge economic loss and deaths but also raised a question whether or not it would trigger any destructive earthquakes on its neighboring segments in the Longmenshan Thrust Zone （LTZ） in the future.展开更多
Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter ...Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap.展开更多
It is attracting more and more attention of seismologists in the world that electromagnetic radiation (EMR) was observed before some strong earthquake occurrence (Takahashi, 1988; Warwick, 1982; Yoshino, 1986 ; Oike,1...It is attracting more and more attention of seismologists in the world that electromagnetic radiation (EMR) was observed before some strong earthquake occurrence (Takahashi, 1988; Warwick, 1982; Yoshino, 1986 ; Oike,1985 ; Fujinawa, 1990 ; Qian. 1992, Zhang, 1992). The international co-operation have promoted the development of this kind of science for getting more data to study SEMR physical mechanism. The observation equipments were provided by Japan, the observation installations were provided by the Seismological Bureau of Yunnan Province. Two observatories were built by Prof. Kozo Takahashi and Yukio Fujinawa, and some Chinese seismologists at Xiao Shao. Kunming, and Yuexi, Dan in Nov. 3～7, 1992. Here, some characters of SEMR in Yunnan Province and prediction efficience of the methods of impending earthquake prediction are obtained. And it was found that before the Pu'er M6. 3 earthquake of 1993, that the occurrence time of EMR signals before strong earthquakes approximately synchronizes some other precursors, for example, of water level, water radon and F-ion. That means the SEMR signals are generated by the activation of the tectonic belt in the seismogenic zone.展开更多
This paper is about short review of earthquake statistics and efforts for earthquake mitigation, hazard and risk assessment studies in Pakistan. Pakistan and adjoining region lying between longitude 60°E to 78...This paper is about short review of earthquake statistics and efforts for earthquake mitigation, hazard and risk assessment studies in Pakistan. Pakistan and adjoining region lying between longitude 60°E to 78°E and latitude 20°N to 45°N are selected for the study as this region has a history of many large earthquakes because of its location in the region of intersection of three plates namely Indian, Eurasian and Arabian Sea plate. This paper is based on the study of both seismological history of the region which includes recent and historical seismicity based on earthquake catalogue as well as geological knowledge supplemented with available fault system information. In this study, Pakistan and adjoining regions are divided into 14 seismogenic zones. Seismicity of each zone is studied considering also the major cities in the respective zone and type of infrastructure which is mainly responsible for earthquake disaster rather than earthquake itself.展开更多
基金jointly supported by the National Natural Science Foundation of China(grant No.41602206)the International Science&Technology Cooperation Program of China(grant No.2011DFG23400)
文摘Objective The occurrence of the devastating Wenchuan earthquake not only caused huge economic loss and deaths but also raised a question whether or not it would trigger any destructive earthquakes on its neighboring segments in the Longmenshan Thrust Zone （LTZ） in the future.
基金supported by the National Natural Science Foundation of China (Grant No. 42104001)。
文摘Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap.
文摘It is attracting more and more attention of seismologists in the world that electromagnetic radiation (EMR) was observed before some strong earthquake occurrence (Takahashi, 1988; Warwick, 1982; Yoshino, 1986 ; Oike,1985 ; Fujinawa, 1990 ; Qian. 1992, Zhang, 1992). The international co-operation have promoted the development of this kind of science for getting more data to study SEMR physical mechanism. The observation equipments were provided by Japan, the observation installations were provided by the Seismological Bureau of Yunnan Province. Two observatories were built by Prof. Kozo Takahashi and Yukio Fujinawa, and some Chinese seismologists at Xiao Shao. Kunming, and Yuexi, Dan in Nov. 3～7, 1992. Here, some characters of SEMR in Yunnan Province and prediction efficience of the methods of impending earthquake prediction are obtained. And it was found that before the Pu'er M6. 3 earthquake of 1993, that the occurrence time of EMR signals before strong earthquakes approximately synchronizes some other precursors, for example, of water level, water radon and F-ion. That means the SEMR signals are generated by the activation of the tectonic belt in the seismogenic zone.
文摘This paper is about short review of earthquake statistics and efforts for earthquake mitigation, hazard and risk assessment studies in Pakistan. Pakistan and adjoining region lying between longitude 60°E to 78°E and latitude 20°N to 45°N are selected for the study as this region has a history of many large earthquakes because of its location in the region of intersection of three plates namely Indian, Eurasian and Arabian Sea plate. This paper is based on the study of both seismological history of the region which includes recent and historical seismicity based on earthquake catalogue as well as geological knowledge supplemented with available fault system information. In this study, Pakistan and adjoining regions are divided into 14 seismogenic zones. Seismicity of each zone is studied considering also the major cities in the respective zone and type of infrastructure which is mainly responsible for earthquake disaster rather than earthquake itself.
