TY - JOUR
T1 - Source of the 1730 Chilean earthquake from historical records
T2 - Implications for the future tsunami hazard on the coast of Metropolitan Chile
AU - Carvajal, M.
AU - Cisternas, M.
AU - Catalán, P. A.
N1 - Funding Information:
This work is part of Chile's Fondo Nacional de Desarrollo Cient?fico y Tecnol?gico, FONDECYT Project N1150321. P.A. Catal?n would like to thank CONICYT through his grants FONDAP 15110017 (CIGIDEN). The authors deeply thank Cristian Araya, Diego Mu?oz, Alejandra Gubler, Carla Zorrilla, and Nicol?s Gorigoit?a for their field and technical support, Rob Wesson for his helpful comments and suggestions, and the Associate Editor and two anonymous reviewers for their valuable and constructive reviews that greatly improved the manuscript. The data used for producing the results herein may be requested by contacting the authors.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/5/1
Y1 - 2017/5/1
N2 - Historical records of an earthquake that occurred in 1730 affecting Metropolitan Chile provide essential clues on the source characteristics for the future earthquakes in the region. The earthquake and tsunami of 1730 have been recognized as the largest to occur in Metropolitan Chile since the beginning of written history. The earthquake destroyed buildings along >1000 km of the coast and produced a large tsunami that caused damage as far as Japan. Here its source characteristics are inferred by comparing local tsunami inundations computed from hypothetical earthquakes with varying magnitude and depth, with those inferred from historical observations. It is found that a 600–800 km long rupture involving average slip amounts of 10–14 m (Mw 9.1–9.3) best explains the observed tsunami heights and inundations. This large earthquake magnitude is supported by the 1730 tsunami heights inferred in Japan. The inundation results combined with local uplift reports suggest a southward increase of the slip depth along the rupture zone of the 1730 earthquake. While shallow slip on the area to the north of the 2010 earthquake rupture zone is required to explain the reported inundation, only deeper slip at this area can explain the coastal uplift reports. Since the later earthquakes of the region involved little or no slip at shallow depths, the near-future earthquakes on Metropolitan Chile could release the shallow slip accumulated since 1730 and thus lead to strong tsunami excitation. Moderate shaking from a shallow earthquake could delay tsunami evacuation for the most populated coastal region of Chile.
AB - Historical records of an earthquake that occurred in 1730 affecting Metropolitan Chile provide essential clues on the source characteristics for the future earthquakes in the region. The earthquake and tsunami of 1730 have been recognized as the largest to occur in Metropolitan Chile since the beginning of written history. The earthquake destroyed buildings along >1000 km of the coast and produced a large tsunami that caused damage as far as Japan. Here its source characteristics are inferred by comparing local tsunami inundations computed from hypothetical earthquakes with varying magnitude and depth, with those inferred from historical observations. It is found that a 600–800 km long rupture involving average slip amounts of 10–14 m (Mw 9.1–9.3) best explains the observed tsunami heights and inundations. This large earthquake magnitude is supported by the 1730 tsunami heights inferred in Japan. The inundation results combined with local uplift reports suggest a southward increase of the slip depth along the rupture zone of the 1730 earthquake. While shallow slip on the area to the north of the 2010 earthquake rupture zone is required to explain the reported inundation, only deeper slip at this area can explain the coastal uplift reports. Since the later earthquakes of the region involved little or no slip at shallow depths, the near-future earthquakes on Metropolitan Chile could release the shallow slip accumulated since 1730 and thus lead to strong tsunami excitation. Moderate shaking from a shallow earthquake could delay tsunami evacuation for the most populated coastal region of Chile.
KW - 1730 Chile earthquake
KW - Metropolitan Chile
KW - central Chile seismic sequence
KW - historical records
KW - tsunami modeling
UR - http://www.scopus.com/inward/record.url?scp=85018964512&partnerID=8YFLogxK
U2 - 10.1002/2017JB014063
DO - 10.1002/2017JB014063
M3 - Article
AN - SCOPUS:85018964512
VL - 122
SP - 3648
EP - 3660
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
SN - 2169-9313
IS - 5
ER -