Maximum Observed Intensity Map for the Azores Archipelago (Portugal) from 1522 to 2012 Seismic Catalog

Fontiela, João; Bezzeghoud, Mourad; Rosset, Philippe; Rodrigues, Francisco Cota

doi:10.1785/0220160159

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…Moreover, the island has grown in a tectonic environment with no significant seismicity recorded between 1926 and 2015 (e.g. 44 , 45 ). Regional seismic events over longer periods cannot be totally excluded, as earthquakes occasionally occur in intra-plate interiors, as reported for the Indian plate 46 .…”

Section: Discussionmentioning

confidence: 99%

Large-scale mass wasting on small volcanic islands revealed by the study of Flores Island (Azores)

Hildenbrand

Marques

Catalão

2018

Sci Rep

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Small intra-plate volcanic islands (total height above seafloor <2500 m) have been considered gravitationally stable. Topographic, stratigraphic, structural and new K/Ar data show that the small island of Flores (Azores) is strongly asymmetric and made up of nested volcanic successions. Along the northwestern coastline, ca. 1.2 Ma lava flows are in lateral contact with a younger volcanic unit (ca. 0.7 Ma), reflecting the existence of a steep lateral discontinuity. From the general dip of the lava flows, their age and the arcuate geometry of the contact, we infer a major landslide that removed the western flank of the older volcano. Further inland, E-dipping lava flows at the summit of the island are ca. 1.3 Ma, suggesting another landslide structure that displaced the whole western half of the former volcanic edifice. Available offshore data show a large hummocky field west of Flores, here interpreted as voluminous debris-avalanche deposits. Unlike the eastern and central Azores islands, Flores sits on a relatively stable tectonic setting. Therefore, we propose that small-size volcanic islands can be sufficiently gravitationally unstable to experience recurrent episodes of large-scale mass wasting triggered by mechanisms other than tectonic earthquakes and thus represent an under-evaluated potential source of hazard and, therefore, risk.

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Section: Discussionmentioning

confidence: 99%

Large-scale mass wasting on small volcanic islands revealed by the study of Flores Island (Azores)

Hildenbrand

Marques

Catalão

2018

Sci Rep

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“…Further details about the kinematics of the Faial earthquake are given in section 5 -Focal mechanism of the large earthquakes. The map of maximum observable intensity (MOI) (Fontiela et al 2017) shows that São Miguel, Terceira, Graciosa, São Jorge, Pico, and Faial have experienced at least one earthquake of MMI ≥ VIII in the last five centuries. According to the MOI maps, the south central part of São Miguel Island is the place where past strong ground shaking has been high (MMI X); on Terceira Island, the northeastern (MMI X) and western (MMI IX) parts are the ones with the highest strong ground shaking; the maximum ground shaking on the eastern part of Graciosa Island is equivalent to MMI IX; on Pico Island, the maximum intensity is VIII (MMI), and on Faial Island, the maximum ground shaking is X (MMI).…”

Section: The Large Earthquakes In the Framework Of The Seismicity Of mentioning

confidence: 99%

Grandes terremotos en Azores

et al. 2017

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Resumen. La historia del archipiélago de Azores, desde el descubrimiento y colonización en la primera mitad del siglo XV hasta ahora, está marcada por los impactos sociales y económicos producidos por los terremotos, principalmente los de alta intensidad. La información compilada nos lleva a concluir que en este periodo 33 terremotos han afectado las islas de Azores con una intensidad igual o superior a VII, causando unas 6.300 muertes y la destrucción generalizada en algunas Islas del Archipiélago, principalmente en S. Miguel, Terceira, Graciosa, Faial, S. Jorge y Pico. La acomodación de los movimientos diferenciales que se producen debido al límite entre las placas eurasiática (EA), africana (AF) y norteamericana (NA) y también al volcanismo que ocurre en la región, son los principales responsables de la intensa actividad sísmica que ocurre en este archipiélago. Este trabajo revisa los temas científicos de los terremotos conocidos que han interferido severamente con la vida del pueblo azoreano a lo largo de su historia, a esos terremotos llamamos grandes terremotos. Palabras clave: Terremotos de Azores; Sismotectónica de Azores; Mecanismo focal de los terremotos de Azores.[en] Large earthquakes in the Azores Abstract. The history of the Azores archipelago, from its discovery and settlement in the first half of the 15th century through the present, is marked by the social and economic impacts produced by earthquakes, mainly the high-intensity ones. Information that has been compiled leads to the conclusion that in this period, 33 earthquakes with intensity equal to or greater than VII have affected the Azores, which caused approximately 6,300 deaths and widespread destruction on some islands of the archipelago, principally S. Miguel, Terceira, Graciosa, Faial, S. Jorge and Pico Islands. The accommodation of strain resulting from the dynamics of the Azores triple junction (ATJ) plate boundary and volcanism, which also occurs in the region, are the main factors responsible for the intense seismic activity in this archipelago. This work reviews the scientific issues of the known earthquakes that have severely interfered with the lives of the Azorean people throughout their history, which we call large earthquakes. Key words: Azores earthquakes; historical earthquakes; seismotectonics of Azores; focal mechanisms.

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