Source Characteristics of the 2007 Pisco Earthquake (Mw=8.0), Central Peru, Derived From Seismic Waveforms Inversion and Tsunami Modeling

We have undertaken a detailed analysis of the source of the 2007 Pisco earthquake based on the modeling of teleseismic and accelerometric records, and taking into account available information on uplift or subsidence along the coastline, as well as run-up heights. Preliminary analysis of the teleseismic P waves, show that the 2007 earthquake was characterized by two distinct sub-events, occurring 60s apart. The inversion of the teleseismic body waves (P and SH) reveals that the first sub-event was located at the hypocenter, and that most of the energy was released by the second patch, in a similar way to the 2001 South Peru earthquake (Mw=8.4). Assuming that the aftershock distribution is a good approximation of the rupture extent (130 km), the duration of the P wave signal bounds the rupture velocity to values below 2 km/s. The small move-out observed between the P wave phases supports this hypothesis, but also limits our ability to clearly resolve between different low rupture velocities. This resolution limitation is also enhanced by the complex geometry of the slab which prevents the correct inversion of the slip history based on a single 2D fault plane. We use earthquake catalogues to better constrain the subduction interface, and consider a multi-plane geometry for our inversion. The directivity of this event confirms the previously identified tendency of large South Peru, and Chile earthquakes to rupture unilateraly to the south.