| The 1755 Lisbon earthquake, which reached a magnitude of 8.5, remains the
most powerful and destructive to hit Europe so far. Within minutes, many
lives were lost, populations displaced, livelihoods, homes and
infrastructures were destroyed. Although frequently associated to the city
of Lisbon, one of the most important European cities at the time, this
earthquake caused similar damage and casualties, if not greater, in the
southwest of the Algarve, where the seismic intensity was estimated at IX-X
Mercalli Intensity Scale. Some time later a tsunami increased the number of
victims and the amount of damage. In some locations the tsunami caused
greater destruction than the earthquake itself. The tsunami hit both coasts
of the North Atlantic; however, the more destructive damage occurred in the
Portuguese coast, south from Lisbon, in the Gulf of Cadiz and in the
Moroccan coast. The downtown of Lisbon was flooded by waves that reached a
height of 6 m. The water flooded an area with an extension of around
250 m from the coast. In the Southwest part of Algarve the waves
reached a height between 10 and 15 m and the flooded area was much
larger. Through the analysis of recent research works on the assessment of
the 1755 tsunami parameters and the interpretation of the more reliable
historical documents, it is our intention to analyse the destructive power
of the tsunami in the Algarve and delimit the flooded area. Using simple
techniques of simulation it is our intention to assess the impacts nowadays
of the occurrence of a tsunami similar to the one that hit the Algarve in
1755, which would probably affect a greater number of people, buildings and
infrastructures. This assessment is an important instrument not only in
terms of disaster preparedness but also for the integration of risk
mitigation measures in land use planning. |