Publication Date:
2023-06-29
Description:
Since 2015, when a cabled observatory was first set up on Axial Seamount, 〉150,000 earthquakes have been located within a 25 km³ block of crust. The volcanic system has also experienced the passage of seismic waves from 〉120 large remote earthquakes and periodic tidal loading. Therefore, it represents a unique laboratory for us to probe how earthquakes respond to static and dynamic stress changes. We find that the seismicity rate increases while the b-value decreases (larger proportion of large events) systematically with increasing tidal stress. The stress dependence of seismicity rate conforms to triggering theory over the whole tidal stress range, demonstrating that there is no triggering stress threshold and stress shadowing is simply a continuous function of stress decrease. We also observe statistically significant episodes of dynamic triggering for ~11% of large remote earthquakes. However, while some coincide with changes in permeability estimated from changes in the tidal phase lag of hydrothermal vent temperature, others are not. Therefore, permeability change is likely not the only mechanism underlying dynamic triggering of earthquakes.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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