Abstract
We present physically realistic models of the 2004 Sumatra-Andaman earthquake using SeisSol, which solves the spontaneous dynamic earthquake rupture problem. Model results suggest high fluid pressure and low differential stresses along the megathrust interface. Using these initial conditions, we show evidence for activation of one long forethrust splaying off the megathrust interface at 45 degrees. 2 m of dip slip along this forethrust transfer directly into 2 m of vertical seafloor displacement, suggesting that splay fault slip contributed to generation of the devastating tsunami that followed the earthquake.
| Original language | English |
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| Pages | 506-507 |
| Number of pages | 2 |
| Publication status | Published - 1 Jan 2017 |
| Event | 14th International Conference on Fracture, ICF 2017 - Rhodes, Greece Duration: 18 Jun 2017 → 20 Jun 2017 |
Conference
| Conference | 14th International Conference on Fracture, ICF 2017 |
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| Country/Territory | Greece |
| City | Rhodes |
| Period | 18/06/17 → 20/06/17 |
Funding
The tsunami wave was up to 30 m high along the northern coast of Sumatra. The height of this wave suggests slip on landward and possibly also seaward dipping faults splaying off the megathrust. This is supported by evidence for active splay faulting from deep seismic reflection surveys, bathymetric data, and relocated seismicity [3-6]. We review evidence for splay faults along the southern extent of the rupture. Using the initial stress conditions constrained by the previous models, we evaluate the influence of splay fault geometries on seafloor uplift in three SeisSol models: without splay faults, with one long forethrust dipping 45 degrees, and with two short forethrusts and two short backthrusts dipping 45 degrees. Only the long forethrust is activated, directly transferring 2 m of dip-slip into 2 m of seafloor uplift. In contrast, 12 m of dip-slip on the 20 degree dipping megathrust results in only 2-3 m of uplift. The authors would like to acknowledge the financial support of the Volkswagen Foundation.