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Along-Strike Variation in Aftershock Productivity of Intermediate-Depth Earthquakes in Japan

Description: 

We show that some intermediate-depth aftershock sequences behave similarly to shallow, crustal earthquakes, even though intermediate-depth earthquakes occur at temperatures and pressures thought to prohibit brittle fracture and are often deficient in aftershocks compared to shallow earthquakes. We search for aftershock sequences of M > 5.5 intermediate-depth earthquakes in two subducting slabs under Japan, and perform a statistical analysis to see if variations in aftershock productivity can be linked to slab properties. Our study regions are the older, colder and steeper Pacific Plate and the younger, warmer, shallower Philippine Sea Plate. We find that productive aftershock sequences have similar spatial extents and decay rates to those of crustal earthquakes and tend to appear mainly within the Pacific Plate where they are significantly correlated with along-strike variations in VP−VS ratio, suggesting a role for fluids in enabling intermediate-depth aftershock activity. Finally, we correlate variations in observed seismic source parameters, such as stress drop and radiated energy, with observations of aftershock productivity.

Session: Structure and Properties of Subducting Slabs and Deep Earthquakes [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Shanna Chu

Student Presenter: No

Invited Presentation: 

Authors