Investigating the physics behind VLFEs and LFEs: analysis based on dynamic rupture models with ductile-like friction

Baoning Wu, David D. Oglesby, Abhijit Ghosh, & Bo LI

Submitted August 2, 2017, SCEC Contribution #7383, 2017 SCEC Annual Meeting Poster #194 (PDF)

Very low frequency earthquakes (VLFE) and low frequency earthquakes (LFE) are two main types of seismic signal that are observed during slow earthquakes. These phenomena differ from standard (“fast”) earthquakes in many ways. In contrast to seismic signals generated by standard earthquakes, these two types of signal lack energy at higher frequencies, and have very low stress drops of around 10 kPa. In addition, the Moment-Duration scaling relationship shown by VLFEs and LFEs is linear instead of for regular earthquakes. However, if investigated separately over a small range magnitudes and durations, the scaling relationship for each is somewhat closer to , not . The physical mechanism of VLFEs and LFEs is still not clear, although some models have explored this issue [e.g., Gomberg, 2016b]. Here we investigate the behavior of dynamic rupture models with a ductile-like viscous frictional property [Ando et al., 2010; Nakata et al., 2011; Ando et al., 2012]. In the model’s framework, VLFE source and LFE source are different because their rupture processes are controlled by different elastic forces. LFE's rupture is mainly controlled by dynamic force, while VLFE's rupture is mainly controlled by static force. Using both analytical and numerical analyses, we show how and why this model may help to explain current observations. This model supports the idea that VLFEs and LFEs are distinct events, possibly rupturing distinct patches with their own stress dynamics [Hutchison and Ghosh, 2016]. The model also makes predictions that can be tested in future observational experiments.

Key Words
very low frequency earthquake, low frequency earthquake, rupture dynamics, ductile friction

Citation
Wu, B., Oglesby, D. D., Ghosh, A., & LI, B. (2017, 08). Investigating the physics behind VLFEs and LFEs: analysis based on dynamic rupture models with ductile-like friction. Poster Presentation at 2017 SCEC Annual Meeting.


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