资源环境科技发展态势分析平台

On 31 March 2020, an M_w 6.5 earthquake struck near Stanley, Idaho. More than 35% non‐double‐couple component in long‐period point‐source solutions indicates a more complex source than slip on a planar fault. Using an integrative analysis of seismological and geodetic data, we find that the Stanley earthquake ruptured a pair of opposing‐dip faults offset by a 10‐km‐wide step, including an unmapped northern subfault with predominantly strike‐slip faulting and a southern subfault sub‐parallel to the Sawtooth fault with predominantly normal faulting. This converging fault geometry allowed the rupture to traverse a surficial 10‐km‐wide step, which is greater than the limiting dimension (3‐4 km) that commonly ceases earthquake ruptures. This study reveals that a composite rupture process with strike‐slip and normal faulting is typical for earthquakes located near the northern boundary of the Centennial Tectonic Belt (CTB), which is distinct from the predominantly normal faulting in the central CTB.

This article is protected by copyright. All rights reserved.