Abstract

ZAVALA, Bilberto et al. Geological process and INQUA macro-seismic intensity scale of Pisco earthquake 15/08/2007, Perú. Rev. Asoc. Geol. Argent. [online]. 2009, vol.65, n.4, pp.760-779. ISSN 0004-4822.

In August 15th, 2007 the cities of Pisco, Ica, Chincha and Cañete, located south of the Peruvian capital city, were affected for a mayor earthquake (7.9 Mw). The final report from the National Institute of Civil Defense totaled 519 casualties and 655 to 679 damaged houses. Cities like Pisco, San Clemente and Tambo de Mora were severely affected, as well as agricultural areas in Pisco and Cañete valleys. The Panamericana highway was considerablely affected. In the National Reserve Paracas many tourist places were destroyed and many secondary roads that connect the coastal area with the high part of the Andes (Ica, Huancavelica and Lima) were blocked due to rock falls. Small towns in the Andes placed on ancient landslide deposits were damaged (Laraos, Chocos, Huangascar, Tantará). Seaside resorts, creeks and small docks in the coastal area and some chicken farms were affected by the tsunami. Coseismic and postseismic geological processes were responsible for the damage in a 200 km radius from the epicenter. Ground deformation and lateral spreading happened in Tertiary sediments due to a shallow of the ground water table. Mass movements (rock fall, collapsing and landslides) are located between 32 and 198 km from the epicenter, with accumulated volumes of 14,750 m³ (Coastal area) and 9, 585 m³ (Andes area). The tsunami waves got 10 m of run up (Yumaque beach) and up to 2 km of flooding at the beach zone (Lagunillas beach) in the National Reserve of Paracas. The geological and geomorphological descriptions of this process determine that that the Pisco earthquake reached a VII and VIII grade on the INQUA macro-seismic intensity scale.

Keywords : Earthquake; Mass movement; Tsunami; Pisco; Perú.

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