Small-scale stress heterogeneity inferred many anti-repeating earthquakes in Sierra Valley, Nevada

Abstract Repeating earthquakes, which occur on overlapping rupture patches with the same focal mechanisms, provide insights into fault creep, earthquake cycle dynamics, triggering, and predictability. Recently, earthquakes with highly anti-correlated waveforms have been systematically reviewed. However, most studies have only observed a small number of anti-repeating earthquake pairs or noted reversals in earthquake focal mechanisms, without connecting these observations to underlying earthquake physics processes. Here we show 37 anti-repeating earthquake pairs ( M : 0.18–1.88) in Sierra Valley deep (~ 32 km) earthquake sequence based on regional waveform analysis. Our high-precision location analysis shows that these anti-repeating earthquake pairs occur on adjacent faults (separated by ~ 240 m), with focal mechanisms indicating that normal and thrust earthquakes can occur within short time intervals. Furthermore, tidal modulation of seismicity in this region suggests a low effective normal stress. We suggest small-scale stress heterogeneity is the mechanism of anti-repeating earthquakes. These findings underscore the necessity of considering both positive and negative components of cross correlation in earthquake studies to better understand the mechanics of fault systems and improve seismic hazard assessment. Graphical abstract