Slip evolution across geometric barrier during the 2018 Palu Indonesia earthquake

Ryo Okuwaki, & Yuji Yagi

Submitted July 27, 2019, SCEC Contribution #9276, 2019 SCEC Annual Meeting Poster #176

How does a slip follow earthquake-rupture front propagating faster than at a local shear-wave velocity (supershear speed)? How does a supershear-rupture front go across geometric discontinuity in a fault system? Resolving in detail such a complex earthquake-rupture evolution should be fundamental to our understanding of earthquake-source physics, but have not been well captured in observation due to limitation of rupture-imaging technique. We resolved both the spatiotemporal evolution of slip and fault geometry of the moment-magnitude 7.5 2018 Palu Indonesia earthquake, in a framework of new finite-fault inversion using the globally observed teleseismic waveforms. Here we show that gross persistency of supershear rupture propagation during the 2018 Palu earthquake is fueled by the transient stagnation and advancing of slip evolution across the geometric discontinuity of the fault. This peculiar inchworm-ish slip evolution results from repeated stress concentration around the fault bends and at a possible fault junction beneath the Palu bay, from the unmapped primary fault in northern Sulawesi island to the pre-known Palu-Koro fault.

Key Words
Slip inversion, Finite-fault modeling, Source observation, Geometric barrier, 2018 Palu Indonesia earthquake

Okuwaki, R., & Yagi, Y. (2019, 07). Slip evolution across geometric barrier during the 2018 Palu Indonesia earthquake. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)