Major earthquakes and tsunami of the Banda Arc region, Indonesia: the past 400 years

Dutch historical records document several large earthquakes and tsunami throughout eastern Indonesia that we use to assess geophysical hazards in this densely populated region. For example, a large earthquake in 1629 generated a tsunami at least 15 m high. The first wave arrived at Banda Neira 30 minuets after violent shaking ceased. The event was followed by at least 8 years of aftershocks and other strong earthquakes over the next few decades. These data are consistent with a mega-thrust earthquake of Mw > 8.8 on the Seram Trough to the east or a >Mw 9.0 earthquake on the Timor-Tanimbar Trough to the south. Smaller tsunami from regional earthquakes that inflicted heavy damage throughout the Banda Arc is also documented in 1648, 1672, 1674 (2 m wave), 1710, 1754, 1778, 1802, 1820 (>20 m wave), 1835, 1836 (wave) and 1852 (8 m wave). These events are likely associated with earthquake activity along the thrust front of the collision zone or along a developing thrust system in the back arc. For example, the > 20 m wave from the 1820 event struck SE Sulawesi after 2-4 minuets of violent shaking throughout a region spanning over 1000 km. The most likely source for this event is the Flores Thrust, which produced a much smaller tsunami from a Mw 7.8 earthquake in 1992. However, the 1820 event is most likely > Mw 8.5 to produce a tsunami as large as the one recorded, 17 years of aftershocks and two possible related nearby volcanic eruptions. Since the seismic drama of 1629-1852, only one earthquake of > Mw 8 is documented in the Banda Arc region, and it was not along the subduction zone interface (Okal and Reymond, 2003). During this time of relative seismic quiescence at least 11 m of strain has accumulated across the active Banda arc-continent collision. A similar scenario is currently playing out in western Indonesia where Dutch records proved extremely reliable in documenting several mega-thrust earthquakes during the 18th and 19th centuries that are reoccurring and have already claimed ~300,000 lives. Based on the seismic history of the Banda Arc region and the large amount of strain that has accumulated during the past 160 years of relative seismic quiescence, it is highly likely that more mega-thrust earthquakes and tsunami are immanent. These events will affect 10 times more people and much larger cities than those of the past.