400 Years of Living Dangerously: Compiling and Communicating to Those in Harms Way the History of Major Earthquake and Tsunami Events in the Sunda-Banda Arc Transition, Eastern Indonesia Region.

Abstract:

Historical records as far back as 1600 document 79 damaging earthquakes and 50 tsunamis in the E. Sunda-Banda Arc transition. One of the largest events in 1629 generated a tsunami that reached a height of >16 m. Another event in 1674 caused a submarine landslide that produced a tsunami >100 m based on the vegetation trim line. An earthquake storm struck the region between 1814 and 1857. During this time there were two mega-earthquakes (1820 and 1852) felt throughout most of Indonesia, which generated tsunamis as high as 26 m. Tsunamis also occurred from earthquakes in 1814, 1818, 1836 and 1857, and the eruption of Tambora (1815). This eruption is the one of the most notable extreme historical geohazards not only in the Indonesian region, but globally. The earthquake storm ended with an event along the north coast of East Timor in 1857, which caused a 3 m tsunami that inundated the capital city of Dili and flooded many villages. Tsunamigenic earthquakes have also struck the area around Kupang, West Timor, which is one of the main commercial centers of the region with a population of half a million. The population of the region is now at least 10 million. Another 2 million people live along the coast of the Makassar Strait, which has experienced 18 tsunamis since the 1820 earthquake. Most people now live in cities, most cities have unreinforced masonry construction and some are in historical tsunami inundation zones. Cities along the NW coast of Australia are also at risk of a tsunami from mega-thrust earthquakes along parts of the Timor Trough, which accumulates strain at the rate of 22 mm/a. No major earthquakes are documented along the Timor to Tanimbar part of the plate boundary since historical records have been kept. However, a major mega-thrust earthquake (8.5-9.0) occurred along the Tanimbar trough in 1852, which caused an 8 m tsunami. We have modeled both the 1629 and 1852 mega-thrust events and used these data to map inundation zones for coastal communities. We have also discovered deposits from these and other tsunamis throughout the region. Much of the historical records are now translated into Indonesian. The WAVES team of the Non-Profit Organization ‘In Harms Way’ is distributing the records throughout the region and has made > 30 presentations in cities and villages in tsunami inundation zones. See inharmswayhelp.org.