Possible Seismic Source Mechanism of the Catastrophic Tsunamigenic Earthquake on May 9, 1877 in Northwestern Chile

• Published in: Pure and applied geophysics 2023-05, Vol.180 (5), p.1695-1715
• Main Authors: Lobkovsky, L. I., Mazova, R. Kh, Baranova, N. A., Alekseev, D. A., Van Den Bosch, F. Jorge, Oses, A. Gustavo
• Format: Article
• Language: English
• Subjects: Catastrophic events; Coastal zone; Coastal zones; Computation; Earth and Environmental Science; Earth Sciences; Earthquakes; Geophysics/Geodesy; History; Isobaths; Kinematics; Mathematical models; Numerical simulations; Seismic activity; Simulation; Tsunami hazard; Tsunamis; Wave height; Weather hazards
• ISSN: 0033-4553; 1420-9136
• DOI: 10.1007/s00024-022-03149-y

Large-magnitude earthquakes in northern Chile and southern Peru occur every 108 years on average. It should be noted that over 143 years since the catastrophic earthquake of May 9, 1877, any similar events were completely absent. In 2007, a 7.7 Mw earthquake occurred near Tocopilla, and in 2014 a catastrophic M  = 8.1 earthquake hit Pisagua. It is believed that only part of the energy accumulated over 143 years has been released during those events, while most of it is yet to be released. Thus, we can conclude that a serious tsunami hazard exists for all coastal cities of southern Peru and northern Chile. In this paper, on the basis of the available historical data and geodynamic studies, numerical simulation of the historical catastrophic earthquake and tsunami of May 9, 1877 is carried out assuming the blockwise earthquake source configurations. We implemented 23 simulation scenarios for different kinematic behavior patterns of such a source, sequentially updating the source fragmentation to reduce the misfit between the simulated and observed wave height data. Using the proposed methodology, for each scenario, the generation of a tsunami source is simulated and the computation of wave fields up to the 5-m isobath is carried out. The results obtained are compared with historical data. Analysis of the entire set of simulated earthquake scenarios makes it possible to choose a tsunamigenic earthquake scenario with the most adequate characteristics of tsunami waves in the coastal zone.