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A theoretical study of correlation between scaled energy and earthquake magnitude based on two source displacement models

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earthquake Science 2013年第6期26卷 373-376页

作者： Jeen-Hwa Wang Institute of Earth Sciences Academia Sinica

The correlation of the scaled energy,e = Es/ Mo, versus earthquake magnitude, Ms, is studied based on two models：（1） Model 1 based on the use of the time function of the average displacements, with a ω^-2 source spectrum, across a fault plane; and （2） Model 2 based on the use of the time function of the average displacements, with a ω^-3 source spectrum, across a fault plane. For the second model, there are two cases：（a） As ζ= T, where r is the rise time and T the rupture time, lg（e） - -Ms; and （b） As ζ 〈〈 T, lg（e）- -（1/2）Ms. The second model leads to a negative value of e. This means that Model 2 cannot work for studying the present problem. The results obtained from Model 1 suggest that the source model is a factor, yet not a unique one, in controlling the correlation of e versus Ms.

关键词： Scaled energy earthquake magnitude Seismic-wave energy Seismic moment Source displacemodel

Comparison between earthquake magnitudes determined by China seismograph network and US seismograph networks (I): Body wave magnitude

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Acta Seismologica Sinica(English Edition) 2005年第6期18卷 627-631页

作者：刘瑞丰陈运泰 Peter Bormann 任枭侯建民邹立晔杨辉 Institute of Geophysics China Earthquake Administration Beijing 100081 China GeoForschungsZentrum D-14478 Potsdam Germany

By using orthogonal regression method, a systematic comparison is made between body wave magnitudes determined by Institute of Geophysics of China earthquake Administration (IGCEA) and National earthquake Information Center of US Geological Survey (USGS/NEIC) on the basis of observation data from China and US seismograph networks between 1983 and 2004. The result of orthogonal regression shows no systematic error between body wave magnitude mb determined by IGCEA and mb (NEIC). Provided that mb (NEIC) is taken as the benchmark, body wave magnitude determined by IGCEA is greater by 0.2-0.1 than the magnitude determined by NEIC for M=3.5-4.5 earthquakes; for M=5.0-5.5 earthquakes, there is no difference; and for M greater than or equal 6.0 earthquakes, it is smaller by no more than 0.2. This is consistent with the result of comparison by IDC (International Data Center).

关键词： earthquake magnitude surface wave body wave

Determination and Comparison of M_(L),M_(S_BB),m_(B),M_(Wp),M_(WW),M_(dt),and M(GNSS)for the 22 May 2021 M7.4 Madoi,Qianghai,China earthquake

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Journal of Earth Science 2022年第4期33卷 847-856页

作者： Xiaolin Huang Yuyang Peng Chuang Cheng Dun Wang Qiang Yao State Key Laboratory of Geological Processes and Mineral Resources School of Earth SciencesChina University of GeosciencesWuhan 430074China

The 2021 Madoi M7.4 earthquake in Qinghai is a major earthquake that occurred in the Bajankara Block of Qinghai-Tibet Plateau in the past 30 years,which spatially filled the seismogenic gap in the eastern section of the northern boundary of the block.Here we determined the values of M_(L),M_(S_BB),m_(B),M_(Wp),M_(WW),M_(dt),and M(GNSS)by abundant regional and global seismic and geodetic observations,which is 6.61,7.43,7.18,7.33,7.43,7.38,and 7.4,respectively.To compare the time efficiency and stability of different magnitude scales,we generated a real-time environment,to iteratively determine the magnitudes over elapsed times.Some methods such as m_(B),M_(S_BB),M_(Wp) gave considerable variations of as large as 0.5 units for the determined magnitudes with elapsed time,as more data were included.Others such as M_(WW) and M_(dt) were very stable with increasing data over time.The systematic calculations of various magnitude scales in this study quantitively evaluated the stability and accuracy of those methods,shading light on the adaptability and applicability of different magnitude scales.

关键词： the 2021 Madoi earthquake earthquake magnitude magnitude scale earthquakes

Last Deglacial Soft-Sediment Deformation at Shawan on the Eastern Tibetan Plateau and Implications for Deformation Processes and Seismic magnitudes

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Acta Geologica Sinica(English Edition) 2019年第2期93卷 430-450页

作者： ZHONG Ning JIANG Hanchao LI Haibing XU Hongyan SHI Wei ZHANG Siqi WEI Xiaotong Institute of Geology Chinese Academy of Geological Sciences Key Laboratory of Deep-Earth Dynamics Ministry of Natural Resources State Key Laboratory of earthquake Dynamics Institute of GeologyChina Earthquake Administration College of Earth Sciences University of Chinese Academy of Sciences College of Geosciences and Resources China University of Geosciences

The eastern margin of the Tibetan Plateau is characterized by frequent earthquakes; however, research of paleo-earthquakes in the area has been limited^ owing to the alpine topography and strong erosion. Detailed investigations of soft-sediment deformation(SSD) structures are valuable for understanding the trigger mechanisms, deformation processes, and the magnitudes of earthquakes that generate such structures, and help us to understand tectonic activity in the region. To assess tectonic activity during the late Quaternary, we studied a well-exposed sequence of Shawan lacustrine sediments, 7.0 m thick, near Lake Diexi in the upper reaches of the Minjiang River. Deformation is recorded by both ductile structures(load casts, flame structures,pseudonodules, ball-and-pillow structures, and liquefied convolute structures) and brittle structures(liquefied breccia, and microfaults). Taking into account the geodynamic setting of the area and its known tectonic activity, these SSD structures can be interpreted in terms of seismic shocks. The types and forms of the structures,the maximum liquefaction distances, and the thicknesses of the horizons with SSD structures in the Shawan section indicate that they record six strong earthquakes of magnitude 6-7 and one with magnitude >7. A recent study showed that the Songpinggou fault is the seismogenic structure of the 1933 Ms7.5 Diexi earthquake. The Shawan section is located close to the junction of the Songpinggou and Minjiang faults, and records seven earthquakes with magnitudes of ?7. We infer,therefore, that the SSD structures in the Shawan section document deglacial activity along the Songpinggou fault.

关键词： lacustrine sequence soft-sediment deformation(SSD) deformation process earthquake magnitude Shawan eastern Tibetan Plateau