Geomorphological changes caused by the seismic event of February 27, 2010 in south-central Chile

Abstract

The 27th February 2010 moment magnitude Mw​=8.8 Maule earthquake was a subduction earthquake in the border between the Nazca and South American plates. The rupture zone was between latitudes 33∘S and 38,6∘S with plate movements close to 10 m. The earthquake is divided in two segments each one associated with one asperity. The southern segment broke first from north to south between latitudes 35,8∘S and 38,6∘S and the northern segment broke approximately one minute later from south to north between latitudes 35,5∘S and 33∘S. This earthquake filled a seismic gap between latitudes 34∘S and 37∘S. The rupture length was much bigger than expected indicating the great energy accumulated and included segments affected by recent earthquakes. Two tsunamis were generated each one corresponding to the rupture segments. The co-seismic vertical movements are typical for subduction earthquakes with uplift close to the trench and subsidence towards the inland. The distance between the trench and the transition zone between uplift and subsidence is bigger in the southern segment than in the northern one, evidencing the shallower position of the northern asperity. A crustal fault was reactivated in Pichilemu (34,19∘S) generating another earthquake in March 11th 2010 with many aftershocks, clearly separated from the main shock.