Seismites and paleotsunamis deposits, assessing for paleoseismicity in Peru

Abstract

[ENG] Human occupation records in Perú provide historical record of large earthquakes prior to the 20th century. In this study, we extend our knowledge of major events by evaluating the stratigraphy and chronology of sediments exposed in various sectors of the Central Andes. These observations suggests that strong seismic activity occurred during the Quaternary, either along the subduction megathrust or on crustal faults. Indeed in Cusco and Colca regions, ,active faults affect fluvio-glacial and alluvial Holocene to Pliocene deposits. High in the topography, lacustrine deposits as well as Quaternary moraines display multiple geomorphic evidences of displacements ans seismites attesting for regional seismotectonic activity. Similarly along the Peruvian coast, 90 excavations succeeded in identifying for the first time paleo-tsunami deposits in southern Peru. Among them, the most impressive are encountered in Puerto Casma and Boca Rio and sign the historic 1619 subduction event and former unknown events (1641 ± 26 years B.P. ie 1668, as well as 2.26 ± 0.37 ka and 1.98 ± 0.23 ka respectively).