The historical reconstruction of the 1755 earthquake and tsunami in downtown Lisbon, Portugal

Abstract

The historical accounts of the 1755 earthquake and tsunami in Lisbon are quite vast providing a general overview of the disaster in the city. However, the details remain unknown. Therefore, the objective of this research is to understand and reconstruct the impact of the 1755 event (earthquake, tsunami, and fire) in downtown Lisbon. Thus, the historical data has been compiled and analyzed, to complement tsunami modeling and a field survey. Although census data are not very accurate, before the disaster there were about 5500 buildings and about 26,200 residents in downtown Lisbon; after the disaster, no records of the buildings were found and there were about 6000-8800 residents. There were about 1000 deaths in the study area. The results also show that the earthquake did not cause significant damage to most of the study area, which contradicts general knowledge. After the earthquake, a fire started that quickly spread throughout the city causing most damage to property. The tsunami hit mostly the west and central parts of the study area. The numerical model results show the tsunami hit the studied area about 60 min after the earthquake, inundating the seafront streets and squares up to 200 m inland. In addition, two major waves were calculated, which are in agreement with the historical accounts.