Diverse rupture processes in the 2015 Peru deep earthquake doublet

Earthquakes in deeply subducted oceanic lithosphere can involve either brittle or dissipative ruptures. On 24 November 2015, two deep (606 and 622 km) magnitude 7.5 and 7.6 earthquakes occurred 316 s and 55 km apart. The first event (E1) was a brittle rupture with a sequence of comparable-size subevents extending unilaterally similar to 50 km southward with a rupture speed of similar to 4.5 km/s. This earthquake triggered several aftershocks to the north along with the other major event (E2), which had 40% larger seismic moment and the same duration (similar to 20 s), but much smaller rupture area and lower rupture speed than E1, indicating a more dissipative rupture. A minor energy release similar to 12 s after E1 near the E2 hypocenter, possibly initiated by the S wave from E1, and a clear aftershock similar to 165 s after E1 also near the E2 hypocenter, suggest that E2 was likely dynamically triggered. Differences in deep earthquake rupture behavior are commonly attributed to variations in thermal state between subduction zones. However, the marked difference in rupture behavior of the nearby Peru doublet events suggests that local variations of stress state and material properties significantly contribute to diverse behavior of deep earthquakes.