强震时空统计分析及InSAR同震形变场空间分布特征

收集整理了全球1976年至2022年初的198个强震（Mw≥7.5）信息，统计分析了强震发生的时空分布、震源深度分布和强震发震类型占比，并结合公开发表的典型强震的合成孔径雷达干涉测量（interferometric synthetic aperture radar，InSAR）同震形变场图，分析了强震同震形变的空间分布特征。研究表明，强震空间分布呈条带状聚集，主要位于环太平洋地震带和喜马拉雅-地中海地震带，强震大多发生在各大板块交界处，与现代大地测量观测到的地壳强应变区域重合；强震时间分布存在活跃期和平静期交替出现的现象，1976―1992年为相对平静期，1992年至今为相对活跃期，强震发生频率有逐年增加趋势；在收集的全球198个强震中，发生在海洋中的强震占大多数，陆地强震仅有44个，且绝大多数强震属于逆冲断层地震，按震源深度统计，浅源强震最多且分布广泛，占比达81.3%；InSAR卫星对地观测新技术可以捕获强震的全域同震形变场，详细呈现强震同震形变的空间范围和分布特征，其中陆地强震同震形变波及的范围主要集中在发震断层两侧附近的条带状区域，离断层越远，形变衰减越快，而且形变关于断层呈不对称性。运用全球覆盖的InSAR和全球导航卫星系统地壳形变监测技术，拼接全球不同位置的活动断层形变信息片段，有可能揭示陆地强震的全周期孕震形变过程。

Temporal and Spatial Statistical Analysis of Strong Earthquakes and Spatial Distribution Characteristics of InSAR Coseismic Deformation Field

  Objectives  It is of important scientific significance for understanding the mechanism of strong earthquakes and evaluating the activity of strong earthquakes around the world.  Methods  We collected the information on 198 strong earthquakes (Mw≥7.5) in the world from 1976 to early 2022, and statistically analyzed the temporal and spatial distribution of strong earthquakes and focal depth, and the proportion of strong earthquake types. Combined with the published typical strong earthquake interferometric synthetic aperture radar (InSAR) deformation map, we analyzed the spatial distribution characteristics of strong earthquake coseismic deformation.  Results  The spatial distribution of strong earthquakes is banded, mainly located in the Pacific Rim seismic belt and the Himalayan-Mediterranean seismic belt. The time distribution of strong earthquakes has the phenomenon of alternating active periods and quiet periods. Most of the 198 earthquakes occurred in the ocean, and most of them are thrust fault earthquakes and shallow source earthquakes. The coseismic deformation of terrestrial strong earthquakes mainly focuses on the strip area near the two sides of the seismogenic fault. The farther away from the fault, the faster the deformation attenuation, and the deformation is asymmetrical about the fault.  Conclusions  Since 1976, the activity of global strong earthquakes above Mw 7.5 shows an overall upward trend. The InSAR deformation field can present the spatial range and distribution characteristics of the coseismic deformation of strong earthquakes in detail. InSAR crustal deformation monitoring technology can be used to splice the deformation information fragments of active faults distributed in different locations around the world. It is possible to reveal the full-cycle seismogenic deformation process of strong land earthquakes.