智利康塞普辛大学Julve Joaqun课题组研究了地质构造对智利地震复发时间和震级的影响。相关论文发表在2023年12月15日出版的《自然—地球科学》杂志上。
研究人员建立了智利南部地震周期的准动态模拟，包括摩擦和粘弹性特性，利用地质和地球物理见解的汇编来解释近期、历史和古地震的复发时间，以及与Melinka和Valdivia地震相关的断层滑动和地壳变形的分布。研究发现，弧前的摩擦和流变特性决定了智利地震的震级和复发模式，而这些特性主要受地质构造和巨型逆冲断层流体分布的控制。
据研究人员介绍，1960年，有史以来最大的地震—Valdivia大地震(矩震级，Mw，9.5)冲击了智利的俯冲带，使整个发震区深度破裂，并沿走向延伸了1,000km。自1960年以来，新的地震能量释放的第一个迹象发生在2017年的Melinka地震(Mw7.6)，仅影响了发震带最深处的一部分。尽管认识到破裂特征和流变学随深度而变化，但研究人员对这种地震大小变化背后的机械控制仍然知之甚少。
附：英文原文
Title: Recurrence time and size of Chilean earthquakes influenced by geological structure
Author: Julve, Joaqun, Barbot, Sylvain, Moreno, Marcos, Tassara, Andrs, Araya, Rodolfo, Cataln, Nicole, Crempien, Jorge G. F., Becerra-Carreo, Valeria
Issue&Volume: 2023-12-15
Abstract: In 1960, the giant Valdivia earthquake (moment magnitude, Mw, 9.5), the largest earthquake ever recorded, struck the Chilean subduction zone, rupturing the entire depth of the seismogenic zone and extending for 1,000km along strike. The first sign of new seismic energy release since 1960 occurred in 2017 with the Melinka earthquake (Mw 7.6), which affected only a portion of the deepest part of the seismogenic zone. Despite the recognition that rupture characteristics and rheology vary with depth, the mechanical controls behind such variations of earthquake size remain elusive. Here we build quasi-dynamic simulations of the seismic cycle in southern Chile including frictional and viscoelastic properties, drawing upon a compilation of geological and geophysical insights to explain the recurrence times of recent, historic, and palaeoseismic earthquakes and the distribution of fault slip and crustal deformation associated with the Melinka and Valdivia earthquakes. We find that the frictional and rheological properties of the forearc, which are primarily controlled by the geological structure and fluid distribution at the megathrust, govern the magnitude and recurrence patterns of earthquakes in Chile.
DOI: 10.1038/s41561-023-01327-8
Source: https://www.nature.com/articles/s41561-023-01327-8