El terremoto de 1647 de Chile central como un evento intraplaca: ¿otra amenaza para Chile metropolitano?

Abstract

RESUMENEl terremoto del 13 de mayo de 1647, la mayor catástrofe en la historia colonial de Chile central, es considerado como el segundo evento de la secuencia de terremotos interplaca que ha ocurrido con una sorprendente regularidad en esta parte de Chile. Sin embargo, el análisis histórico realizado sugiere que este terremoto, además de generar un enérgico y extenso sacudimiento en el valle central, no habría producido un tsunami. Ambas características podrían signifi car que se trató de un evento tipo intraplaca, originado superfi cialmente en la placa continental o profundo en la de Nazca. Los efectos reportados se asemejan más a los del terremoto de Chillán de 1939, un evento intraplaca de profundidad intermedia que aunque no produjo un tsunami generó grandes intensidades en el valle central y una enorme cantidad de víctimas. Si el terremoto de 1647 fue intraplaca, se plantea un problemático escenario de riesgo para la región más poblada del país.Palabras clave: Terremoto de 1647, terremoto intraplaca, sismología histórica, Chile central. ABSTRACTThe May 13, 1647 earthquake, the larger catastrophe in the colonial history of central Chile, is considered as the second event of the inter-plate earthquakes series that has occurred at regular intervals in this part of Chile. However, this historical analysis suggests this earthquake, besides generating a strong and widespread shaking in the central valley, did not produced a tsunami. Both features could imply it was an intra-plate event, sourced in the surface of the continental plate or deeper in the Nazca plate. The reported effects resemble those from the 1939 Chillan earthquake, a middle-depth intra-plate event that although it did not produce a tsunami it does generated large intensities in the central valley and a huge number of victims. If the 1647 earthquake was intra-plate, a problematic risk scenario is set for the most populated region of the country.

Coastal evidence for Holocene subduction-zone earthquakes and tsunamis in central Chile

“…We exclude the AD 1575, 1580, and 1647 earthquakes from this sequence because there are no accounts of accompanying tsunamis; thus, there is a possibility that they were not megathrust earthquakes (Cisternas, 2012;Cisternas et al, 2012;Udías et al, 2012). The three most recent ruptures (AD 1822(AD , 1906(AD , and 1985 may have been limited in their southern extent by the Juan Fernandez Ridge asperity (Fig.…”

Source of the 1730 Chilean earthquake from historical records: Implications for the future tsunami hazard on the coast of Metropolitan Chile

“…The historical sequence of large earthquakes ( M w > 8) that clearly ruptured the plate interface of Metropolitan Chile started in 1730 and continued in 1822, 1906, and 1985. Other historical events in 1575, 1580, and 1647 were either likely smaller than M w 8.0 (1575 and 1580) or are best explained by intraplate slip (1647), either within the Nazca Plate or within the South America Plate, rather than between these plates [ Lomnitz , ; Cisternas et al , ; Cisternas , ]. Despite the remarkably constant recurrence interval (~85 years), the earthquakes produced effects that varied in both magnitude and extent, suggesting sources of different sizes and characteristics.…”