Lessons from the Valdivia (Mw=9.5) and El Maule (Mw=8.8) mega-thrust earthquakes

抄録

The Valdivia (1960) and El Maule (2010) earthquakes of Moment Magnitudes 9.5 and 8.8, respectively, can be considered mega-earthquakes, as others of similar magnitudes. These mega-earthquakes have some singularities as the occurrence of significant co-seismic displacements of the bedrock that especially affect the stability of natural slopes. Additionally, ground subsidence is observed as a result of variations in the water table and/or densification of soils due to vibrations. Furthermore, coastal areas are affected by large tsunamis, usually of catastrophic characteristics. The rupture zones of the mega-earthquakes have been as large as 1000 km, making useless the attenuation laws in the affected area. The duration of the seismic records is significant, which increases the possibility of liquefaction of sandy soils and, in general, the occurrence of damage to all types of structures. This article analyzes the unique characteristics of both the 1960 Chilean Valdivia mega-earthquakes and the recent Maule earthquake occurred in 2010.