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Journal: |
Journal of Geophysical Research 0000 No.
clicks:267 |
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Title:
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Author:
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Gang Luo1 and Mian Liu1,2 |
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Adress: |
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Abstract:
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Intensive studies following the 2008 Wenchuan and 2013 Lushan earthquakes have shown that
these two events have changed stresses on major faults in eastern Tibetan Plateau. However, these stress
changes are small perturbations to total stresses on these faults. To evaluate full stress evolution on faults and
the associated earthquake hazard, we need to consider the effects of all regional large earthquakes and
tectonic stressing on faults. Here we use a three-dimensional viscoelastoplastic finite element model to
investigate stress evolution and long-term temporal patterns of seismicity on major faults in eastern Tibet.
We first simulate stress changes due to coseismic slips and postseismic viscoelastic stress relaxation by
regional 28 big earthquakes since 1327 and find that nine events, including the Wenchuan earthquake,
occurred where Coulomb stress was decreased by the preceding events. We then evaluate interseismic
stressing rates using the geodynamic model and GPS data and find the highest rate on Xianshuihe fault
(~1,000–4,950 Pa/yr) and the lowest rate on Longmenshan fault (~150–1,133 Pa/yr). Including interseismic
stressing in stress evolution shows that the Wenchuan earthquake ruptured where Coulomb stress had
increased since 1327 and stresses on southern Xianshuihe and central Anninghe faults would have reached
prerupture stress levels of their preceding ruptures. Finally, we analyze synthetic seismicity on faults and find
that earthquakes on each fault tend to occur in clusters, separated by quiescent periods whose lengths are
inversely related with fault slip rates. The time spans of earthquake clusters are affected by fault slip rates,
fault configuration, and rheology |
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Comment: |
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