Methodological Reconstruction of Historical Seismic Events From Anecdotal Accounts of Destructive Tsunamis: A Case Study for the Great 1852 Banda Arc Mega‐Thrust Earthquake and Tsunami

We demonstrate the efficacy of a Bayesian statistical inversion framework for reconstructing the likely characteristics of large pre‐instrumentation earthquakes from historical records of tsunami observations. Our framework is designed and implemented for the estimation of the location and magnitude of seismic events from anecdotal accounts of tsunamis including shoreline wave arrival times, heights, and inundation lengths over a variety of spatially separated observation locations. The primary advantage of this approach is that all of the assumptions made in the inversion process are incorporated explicitly into the mathematical framework. As an initial test case we use our framework to reconstruct the great 1852 earthquake and tsunami of eastern Indonesia. Relying on the assumption that these observations were produced by a subducting thrust event, the posterior distribution indicates that the observables were the result of a massive mega‐thrust event with magnitude near 8.8 Mw and a likely rupture zone in the north‐eastern Banda arc. The distribution of predicted epicentral locations overlaps with the largest major seismic gap in the region as indicated by instrumentally recorded seismic events. These results provide a geologic and seismic context for hazard risk assessment in coastal communities experiencing growing population and urbanization in Indonesia. In addition, the methodology demonstrated here highlights the potential for applying a Bayesian approach to enhance understanding of the seismic history of other subduction zones around the world. Plain Language Summary Using modern statistical techniques, we reconstruct the magnitude, and centroidal location of an historical earthquake (1852) in the Banda Sea of eastern Indonesia. This is done by matching historical records of tsunami impact and damage to various locations in the greater Banda arc with high fidelity simulations of earthquake induced tsunamis. Key Points Bayesian inference is used to find the likely location and magnitude of a historical, mega‐thrust earthquake in eastern Indonesia The 1852 Banda earthquake and resultant tsunami can be attributed to a mega‐thrust earthquake along the outer Banda arc Bayesian inference can be used to quantify the nature of pre‐instrumental natural hazards using anecdotal evidence