Seismic Retrofitting: Learning from Vernacular Architecture – Correia, Lourenço & Varum (Eds) © 2015 Taylor & Francis Group, London, ISBN 978-1-138-02892-0

The high and intense seismic activity in the

F. Gomes, M.R. Correia, G.D. Carlos & A. Lima CI-ESG, Escola Superior Gallaecia, Vila Nova de Cerveira,

ABSTRACT: The archipelago of the Azores is situated in a seismic area of high intensity characterised by the frequency of seismic events. The 1980 and 1998 , according to the collected data, caused elevated damages and made possible the identification of seismic-resistant elements, as the prominent foundation and the reinforcement of the internal structure (wood box). Terceira and Faial reveal a local seismic culture presented throughout their history, though inactive. There is an obvious oblivion of the seismic risk, which led to a progressive abandonment of the application of the seismic-resistant elements in the dwelling.

1 INTRODUCTION

1.1 Context: The archipelago of the Azores The Azores region comprises nine islands of volcanic origin, with several dimensions and configurations. Its geographical location, stipulates the climate of the archipelago, presenting different climatic charac- teristics in the different islands, and in each microclimates are also identified. Manly linear, the Azorean settlements are, favourably, parallel to the coast. They can also appear with a perpendicular track, when accompanying water lines.

2 HISTORIC SEISMICITY: THE AZORES Figure 1. Map of the Azores archipelago. Identification of REGION the case studies (credits: CI-ESG).

The archipelago of the Azores presents an important Table 1. Main earthquakes in the Azores. (Nunes et al., historical seismic activity characterised by the sys- 2004). tematic seismic crises, the significant and elongated Year Place Intensity Esc. Mercalli (MCS) volcanic activity and its geographic location, near the | triple point associated to the joining of the Eurasian, African and Northern American plates. In the course 1522 S. Miguel X 1614 Terceira IX of the XX century, the seismic crises of elevated inten- 1757 Pico/S. Jorge X sity affected greatly the Faial Island in 1973 and the 1801 Terceira VIII in 1980. Later, in 1998, the most recent 1841 Terceira IX seism in the archipelago of the Azores, affected seri- 1852 S. Miguel VIII ously the Faial Island. Thus, through the revision of 1973 Pico/Faial VII the literature focused on the historical seismic occur- 1980 Terceira IX rences and damages caused, appear as study objects 1998 Faial IX the Terceira and the Faial islands.

3 CASE STUDIES: FAIAL AND TERCEIRA During this , more than 3000 build- ings were totally or partially destroyed, much of it Over the last centuries, the Terceira Island suffered on Terceira Island, particularly in the city of Angra from several earthquakes, the latest of which occurred do Heroísmo.80%ofthebuildingsinthiscitywere on the 1st of January 1980. destroyed and extensive damage occurred also in the

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