Three-dimensional electrical resistivity structure reveals the cascade rupture process of the 1988 Lancang-Gengma earthquake doublet

Abstract

Earthquake doublets—two large earthquakes occurring in close succession—pose challenges for understanding fault interaction and rupture dynamics. This study employs three-dimensional magnetotelluric imaging to investigate how crustal resistivity structure influences the 1988 Lancang-Gengma earthquake doublet in southwestern China. The resistivity model reveals a high-resistivity anomaly (R1), interpreted as a rigid asperity between the two epicenters, flanked by conductive fault zones (C1 and C2). R1 likely acted as a stress accumulation zone, while C1 and C2 serve as weakened fault segments that facilitate rupture propagation. The interaction between these contrasting resistivity domains controlled the cascading rupture sequence. These results underscore the influence of crustal electrical heterogeneity on large intraplate earthquake dynamics and offer new insights into fault interaction and stress transfer.