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Estimating Magnitudes of the 1868 and 1877 Earthquakes Using Tsunami Records

Description: 

As is the case in most of the western coast of South America, southern Peru and northern Chile have been exposed to several great earthquakes and catastrophic tsunamis. Two of the largest events that affected these coasts took place in the latter part of the XIX century: the August 13, 1868, and the May 9, 1877 (local time), earthquakes. Their magnitudes have been estimated between 8.5 and 9, rupturing contiguous segments several hundred km each.

Both events accommodated the convergence between Nazca and South American plates producing large seafloor and coastal elevation changes. These changes generated significant tsunamis that affected, not only the coasts close to the rupture regions -with reported local run-ups reaching values of the order of 20 m- but also were observed along most of the coastlines of the Pacific Ocean basin. Local reporting times of tsunami arrivals in relation to the time of occurrence of both earthquakes have been used to estimate their rupture areas by using inverse ray tracing.

In addition, both trans-pacific tsunamis were recorded at the tide gauge located in Fort Point, in San Francisco Bay, California. Here, we report on the characteristics of these records and compare them to recent records of tsunamis produced by the largest earthquakes in the region. We report as well on the numerical simulations of both tsunamis on this tide gauge.

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Sergio E. Barrientos

Student Presenter: No

Invited Presentation: 

Authors