APPLICATIONS OF TSUNAMI MODELING: ASSESSING THE VALIDITY OF MATCHING ON-LAND OBSERVATIONS TO EARTHQUAKE SOURCE SCENARIOS, SOUTH-CENTRAL CHILE

A long-term goal of paleotsunami studies is the ability to predict paleoearthquake parameters based on tsunami deposits found on land. Central Chile provides an exemplary location for testing methodologies because the historical record includes 41 major earthquakes as far back as 1562 AD, and paleotsunami deposits are well studied in the region. Using these records as a comparison tool, we evaluated simulated tsunami heights and inundation extent with the tsunami model GeoClaw from nine hypothetical tsunamigenic large earthquakes (Mw 8.6, 8.8, and 9.0) in south-central Chile with epicenters at -35.1º, -38.8º, and -42.9º. As expected, increasing earthquake magnitude produces larger tsunami wave heights, generally earlier arrival times and greater values of coseismic subsidence and uplift. Simulations showed tsunamis from Mw 9.0 earthquakes can inundate coastal plains from nearfield sources, but not exclusively as Mw 8.6 and Mw 8.8 earthquake tsunamis can produce wave heights over 5 m at some sites. At paleotsunami deposit locations, at least one of the three earthquake epicenter locations can be ruled out as a possible source area. These nine earthquakes show that more extensive comparisons of possible paleoearthquake parameters with on-land observations is a promising approach to defining characteristics of historical and prehistoric events.