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Slow‐slip evolves into megathrust earthquakes in 2D numerical simulations
Author(s) -
Segall Paul,
Bradley Andrew M.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl052811
Subject(s) - slip (aerodynamics) , cabin pressurization , geology , nucleation , dilatant , instability , slow earthquake , thermal , mechanics , pore water pressure , subduction , stress (linguistics) , seismology , geotechnical engineering , materials science , tectonics , interplate earthquake , thermodynamics , composite material , linguistics , philosophy , physics
Slow slip events (SSE) in many subduction zones incrementally stress the adjacent locked megathrust, suggesting that they could potentially either trigger or evolve into damaging earthquakes. We explore this with 2D quasi‐dynamic simulations with rate‐state friction, dilatancy, and coupled 1D pore‐fluid and heat transport. Steady‐state weakening friction allows transient slip to nucleate, but is inhibited by dilatant strengthening and destabilized by thermal pressurization. SSE spontaneously nucleate in Low Effective‐Stress Velocity‐Weakening (LESVW) regions. If the dimension of the LESVW is relatively small the SSE are trapped at its updip end, imparting a strong stress concentration in the locked zone. After several centuries SSE penetrate into the region of higher effective stress, where thermal pressurization eventually leads to dynamic rupture. For larger LESVW regions SSE tend to increase in length with time; ultimately higher slip speeds enhance thermal weakening, leading to dynamic instability within the SSE zone. In both cases the onset of the ultimate SSE is essentially indistinguishable from preceding events.