Systematic Detection of Short-Term Slow Slip Events in Southcentral Alaska

Slow slip events (SSEs) are important for the slip budget along a megathrust fault. Although the recurrence of weeks-long short-term SSEs (S-SSEs) in southcentral Alaska has been suggested, a large amount of noise prevented us from detecting discrete events. We applied a systematic detection method to Global Navigation Satellite System data and detected 31 S-SSEs during the 14-year analysis period. The events mainly occurred at a depth from 35 to 45 km at a down-dip extension of the 1964 Alaska earthquake, and the active clusters correlated with the region of the subducting Yakutat microplate. A large cumulative slip of S-SSEs indicated a significant contribution to stress transfer along the plate interface, and its source area spatially coincided with that of the long-term SSEs and the afterslip of the 1964 earthquake. Large and recurrent S-SSEs are key phenomena for understanding interplate slip kinematics in this region. Slow and transient fault slips, called slow slip events (SSEs), are important phenomena accommodating plate motion during interseismic periods. However, detecting SSEs, especially short-term SSEs (S-SSEs) that last from days to weeks, is sometimes difficult because of their weak signals. In southcentral Alaska, previous studies have detected S-SSEs as several discrete events synchronizing with tectonic tremors, but their spatiotemporal distribution and the features of their magnitude and duration are still unclear. We applied a systematic detection method to 14 years of daily Global Navigation Satellite System position data and successfully detected 31 S-SSEs. We found two major groups of S-SSEs (S-SSE clusters) at a depth from 35 to 45 km, which corresponds to a deeper extension of the source of the 1964 Alaska earthquake. These clusters are located in the region where the Yakutat microplate subducts. Maximum cumulative slip reaches 0.27 and 0.43 m in the western and eastern clusters, respectively, and it suggests that S-SSEs contribute to the reduction of the large amount of interplate slip in their source areas. Systematic detection identified 31 short-term slow slip events in southcentral Alaska from 14 years of Global Navigation Satellite System dataThe slow slips were located at a depth from 35 to 45 km, particularly in the region where the Yakutat microplate subductsThe short-term slow slips overlap the source areas of the long-term slow slips and the 1964 Alaska earthquake afterslip

Automated summary

In southcentral Alaska, 31 short-term slow slip events (S-SSEs) were detected using Global Navigation Satellite System data. These events mainly occurred at a depth of 35 to 45 km, correlating with the down-dip extension of the 1964 Alaska earthquake and the subducting Yakutat microplate. The findings highlight the importance of short-term slow slip events for understanding interplate slip kinematics in this region.