Focusing Seismic Energy along Faults through Time-Variable Rupture Modes: Wenchuan Earthquake, China
- Received Date: 2018-07-15
- Rev Recd Date: 2018-07-15
- Publish Date: 2018-07-15
Abstract: Field analysis and differential interferometry derived from Synthetic Aperture Radar (PALSAR) of the epicentral area of the May 12 2008 Mw 8.0 Wenchuan (汶川) earthquake zone reveal details about fault ruptures and ground displacements, with field-documented vertical offsets reaching 12 m along the trace of the main fault rupture, and PALSAR-measured horizontal displacements reaching 12.3 m. We document slip indicators on the fault scarp that show initially sub-horizontal then progressively steeper slip increments with time along the same fault during the 2 min earthquake, suggesting that the rupture propagated as a mixed Mode II–III fracture, with strike-slip movement at the tip directing energy from the initial rupture to points north of the epicenter, followed by vertical displacement in the interior of the slipped region...