In 1852, a five-minute long earthquake hit the Banda Arc region that was felt over most of Indonesia. It caused uplift of new islands and sent a tsunami across the Banda Sea that reached a height of 8 meters at Banda Neira and was also registered at Ambon, Saparua and other islands. Records of the 1852 earthquake at multiple locations provide the constraints needed to reconstruct the disastrous event through earthquake intensity analysis and numerical modeling of the tsunami. Using tsunami heights and arrival times as the major constraints, best fit numerical models of the tsunami were constructed using Clawpack. These models indicate that the earthquake was most likely a mega-thrust event along the Tanimbar Trough with a Mw of around 8.4. At least 10-15 meters of elastic strain energy has accumulated along the Tanimbar Through since the 1852 event, and the population in the region has increased exponentially. When another event occurs ≥ that in 1852, there will be many more people and treasure in harms way.