Speaker
Prof.
diego salazar
(universidad de chile)
Description
The subduction margin of the Central Andes is characterized by the occurrence of large earthquakes associated with the convergence of the Nazca and South American Plates at about 6.5-7.0 cm/yr (DeMets et al., 1994; Angermann et al., 1999; Béjar-Pizarro et al., 2010). This convergence rate is responsible for causing giant tsunamigenic subduction earthquakes like the 1868 Mw 8.8 and 1877 Mw 8.8 events that affected vast areas along southern Peru and northern Chile (Kausel, 1986; Dorbath et al., 1990; Comte and Pardo, 1991; Fig. 1). In particular, the last giant earthquake in 1877 ruptured ~450-500 km along northern Chile, producing tsunami waves of up to 20 meters in the epicentral area (Kausel, 1986; Comte y Pardo, 1991), but that equally impacted neighbouring coastal areas.
Today, northern Chile is considered a mature seismic gap (Kelleher, 1972; Nishenko, 1985; Kausel, 1986). Unfortunately, the historical seismic record of the region is only two hundred years long (Comte and Pardo, 1991), and the hyperarid and rocky landcsape of most coastal areas have hindered systematic paleosismological research on the coastal platform. Therefore, our knowledge about earthquake occurrence along this hyperarid subduction margin is still very limted.
In this paper we present results of an interdisciplinary research aiming to fill this gap by identifying Holocene tsunamigenic subduction earthquakes along the coast of northern Chile, and their effects on prehistoric human populations. Our research has combined different approaches to the geological, geomorphological, archaeological and historical records.
Our results indicate the ocurrence of tsunamigenic megaearthquakes of different intensities at 500 BP, 950 BP, 1300 BP, 1500 BP and 4000 BP. The latter date coincides with major transformations in human demography and local settlement systems, suggesting causal links between catastrophic events and historical change.
This discovery may have significant implications for the understanding of cultural changes/adaptation in relation to extreme natural disasters, and for seismic and tsunami hazard assessment in the present.
Primary author
Prof.
diego salazar
(universidad de chile)
Co-authors
Prof.
James Goff
(university of new south wales)
Prof.
gabriel vargas
(universidad de chile)
Dr
jean louis guendon
(cnrs (retired))
Prof.
pedro andrade
(universidad de concepción)
Mr
tomas leon
(universidad de chile)
