Lessons in earthquake nucleation drawn from subduction zones and ice streams

Emily E. Brodsky

Submitted August 27, 2020, SCEC Contribution #10783, 2020 SCEC Annual Meeting Talk on TBD

The 2014 M8.1 Iquique earthquake and the 2011 M9.0 Tohoku earthquake have provided the most promising evidence to date that a slow precursory slip may exist before at least some earthquakes. These apparent precursors are observable because they are significantly larger than would be predicted from a spontaneous, self-nucleation model. They raise the possibility that earthquake nucleation is a distributed process involving migratory slip, and hence more observable than early models would suggest. However, it is unclear whether such migratory nucleation is a common occurrence. The Whillans ice stream in Antarctica generates M7 slip events each day and an opportunity to evaluate the relative abundance of migratory and self-nucleation in a natural system through near-fault instrumentation. Barcheck et al. (submitted) find that migratory nucleation predominates with positive evidence existing for 61% of the events. Only 3% of the events have evidence for self-nucleation and the record is ambiguous for the remaining events. Migratory nucleation appears to be dominant in at least one large-scale, natural stick-slip system and likely stems from the inherent heterogeneity of the fault. Since tectonic faults are likely more heterogeneous than ice stream bases, one might speculate that migratory nucleation is more common in nature.

Brodsky, E. E. (2020, 08). Lessons in earthquake nucleation drawn from subduction zones and ice streams. Oral Presentation at 2020 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)