Open AccessUnraveling the apparent magnitude threshold of remote earthquake triggering using full wavefield surface wave simulation
Author(s) -
Parsons Tom,
Kaven J. Ole,
Velasco Aaron A.,
GonzalezHuizar Hector
Publication year - 2012
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2012gc004164
Subject(s) - geology , seismology , seismogram , magnitude (astronomy) , amplitude , slip (aerodynamics) , induced seismicity , thrust fault , seismic moment , fault (geology) , stress (linguistics) , cauchy stress tensor , surface wave , telecommunications , linguistics , philosophy , physics , classical mechanics , quantum mechanics , astronomy , computer science , thermodynamics
Empirical studies with earthquake catalogs suggest that large events ( M > 5) are rarely triggered in significant numbers by passing surface waves at remote distances from main shocks. Triggered, small (M < 5) earthquakes are routinely associated with the passage of surface waves from large ( M > 7) main shocks. Since large earthquakes involve larger rupture areas, we study the spatial and temporal characteristics of dynamic stress change for clues. Using a 3D finite element method, we model the complete wavefield from the 2002 M = 7.9 Denali earthquake recorded near the Wasatch Front in Utah, where details about triggered seismicity are known. In particular, we load our model with a displacement seismogram to acquire a time series of the stress change tensor and model failure of a representative normal fault based on these stress changes. We note that the stress‐change regime varies rapidly between favoring strike‐slip, thrust, and normal faulting, with durations lasting ∼1–4 s. We find that these stress regimes usually affect only some fraction of a fault surface at any given time. Stress amplitudes also vary, meaning that ideal conditions for triggering are short‐lived and spatially limited. Stress conditions can also rapidly reverse to regimes that inhibit slip. Given these stressing conditions, we conclude that it may be difficult for a larger rupture area to experience the temporally and spatially coherent stress change necessary to develop into a large magnitude earthquake.