Magnitude of the 23 January 2018 M7.9 Alaska Earthquake Estimated from Local Dense Seismic Records in Alaska  

作　　者：Chen Song Qiang Yao Dun Wang 

机构地区：[1]Key Laboratory of Earthquake Geodesy, Institute of Seismology, China Earthquake Administration, Wuhan 430071, China [2]State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China

出　　处：《Journal of Earth Science》2019年第5期1005-1009,共5页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 41474050);the Fundamental Research Funds for the Central Universities, the China University of Geosciences (Wuhan) (No. CUG170602);the National Programme on Global Change and Air-Sea Interaction (No. GASIGEOGE-02)

摘　　要：We apply a novel method to estimate the magnitude of the 23 January 2018 M7.9 Alaska earthquake using seismic stations recorded at local to regional distances in Alaska, US. We determine the source duration from back-projection results derived from the Alaska stations in a relatively compact azimuth range. Then we calculate the maximum P-wave displacements recorded on a wide azimuth range at distances of 8 to 15 degrees. Combining the source duration and the maximum P-wave displacements, we obtain magnitudes of 7.86–8.03 for the 23 January 2018 earthquake in 3–5 min, very close to the Mw 7.9 determined by the USGS and GCMT. This example validates the new approach for determining magnitude of large earthquakes using local to regional stations, and its time efficiency that magnitudes of large earthquakes can be accurately estimated within in 3–5 min after origin time. Therefore, further application of this new method would help accurate estimation of size of earthquakes that occur offshore and might cause tsunami hazards.We apply a novel method to estimate the magnitude of the 23 January 2018 M7.9 Alaska earthquake using seismic stations recorded at local to regional distances in Alaska, US. We determine the source duration from back-projection results derived from the Alaska stations in a relatively compact azimuth range. Then we calculate the maximum P-wave displacements recorded on a wide azimuth range at distances of 8 to 15 degrees. Combining the source duration and the maximum P-wave displacements, we obtain magnitudes of 7.86–8.03 for the 23 January 2018 earthquake in 3–5 min, very close to the Mw 7.9 determined by the USGS and GCMT. This example validates the new approach for determining magnitude of large earthquakes using local to regional stations, and its time efficiency that magnitudes of large earthquakes can be accurately estimated within in 3–5 min after origin time. Therefore, further application of this new method would help accurate estimation of size of earthquakes that occur offshore and might cause tsunami hazards.

关 键 词：rapid MAGNITUDE estimation BACK-PROJECTION real-time SEISMOLOGY TSUNAMI WARNING GEOPHYSICS 

分 类 号：P[天文地球]