| Since the settlement of S. Miguel Island (Azores), in the XV century,
several earthquakes caused important human losses and severe damages on the
island. Sete Cidades Volcano area, located in the westernmost part of the
island, was attained by strong seismic crises of tectonic and volcanic
origin and major events reached a maximum historical intensity of IX
(European Macroseismic Scale 1998) in this zone.
Aiming to evaluate the impact of a future major earthquakes, a field survey
was carried out in ten parishes of Ponta Delgada County, located on the
flanks of Sete Cidades volcano and inside it is caldera. A total of 7019
buildings were identified, being 4351 recognized as dwellings. The total
number of inhabitants in the studied area is 11429.
In this work, dwellings were classified according to their vulnerability to
earthquakes (Classes A to F), using the structure types table of the EMS-98,
adapted to the types of constructions made in the Azores. It was concluded
that 76% (3306) of the houses belong to Class A, and 17% (740) to
Class B, which are the classes of higher vulnerability.
If the area is affected by a seismic event with intensity IX it is
estimated, that 57% (2480) to 77% (3350) of the dwellings will
partially or totally collapse and 15% (652) to 25% (1088) will need to
be rehabilitated. In this scenario, considering the average of inhabitants
per house for each parish, 82% (9372) to 92% (10515) of the population
will be affected. The number of deaths, injured and dislodged people will
pose severe problems to the civil protection authorities and will cause
social and economic disruption in the entire archipelago. |