Seismicity, source mechanisms and tectonics of the Azores-Gibraltar plate boundary

Buforn, E.; Udías, Agustín; Colombás, M.A.

doi:10.1016/0040-1951(88)90031-5

Cited by 252 publications

(170 citation statements)

References 24 publications

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“…The distribution of more than 400 aftershocks of the January 1, 1980, earthquake recorded by the telemetric seismic network installed on Terceira, S. Jorge, Graciosa, and Pico Islands shows a N150°E trend; this agrees with one of the fault planes estimated for the main shock and indicates pure left-lateral strike-slip motion along a vertical plane between 149° and 154° (Buforn et al, 1988;Grimison and Chen (1988);Hirn et al, 1980). Hirn et al (1980) obtained a composite solution for the aftershocks that coincides with that for the main event using polarities recorded by a temporary network.…”

Section: Focal Mechanisms Of the Large Earthquakessupporting

confidence: 67%

“…The AP stands out clearly from the abyssal plain, whose depths can exceed 3,500 m, and presents a strongly irregular topography consisting of peaks and volcanic ridges that reach the surface in seven places coincident with seven of the nine Azores islands (Corvo and Flores Islands lie within the North American (NA) plate). The Azores Plateau is traversed in the N-S direction by the Mid-Atlantic Ridge (MAR), and its boundaries are: the North Azores Fracture Zone (NAF) with an E-W trend, which continues into the Terceira Rift (TR), trending SE and including the S. Miguel-Terceira-Graciosa, Faial-Pico and S. Jorge alignments, and the East Azores Fracture (EAF) striking E-W to the south, continuing to the Gloria Fault (GF) (Buforn et al, 1988;Luis et al, 1994).…”

Section: Geodynamic and Seismotectonic Setting Of The Azoresmentioning

confidence: 99%

“…Different explanations have been proposed for the origin of the Terceira Rift. According to some authors, this ridge corresponds to an extensional zone normal to the MAR (Udías et al, 1976;Buforn et al, 1988;Udías 1980) or an oblique extension zone (McKenzie, 1972;Searle, 1980). Madeira and Ribeiro (1990) proposed a leaky transform model.…”

Section: Geodynamic and Seismotectonic Setting Of The Azoresmentioning

confidence: 99%

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Seismic swarms, fault plane solutions, and stress tensors for São Miguel Island central region (Azores)

et al. 2012

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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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Section: Focal Mechanisms Of the Large Earthquakessupporting

confidence: 67%

Section: Geodynamic and Seismotectonic Setting Of The Azoresmentioning

confidence: 99%

Section: Geodynamic and Seismotectonic Setting Of The Azoresmentioning

confidence: 99%

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Seismic swarms, fault plane solutions, and stress tensors for São Miguel Island central region (Azores)

et al. 2012

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“…The tectonic pattern of this area operates as a strike-slip movement in the western part (Azores) and as a north-south compression to the east (Gibraltar) ( Udias et al, 1976;Buforn et al, 1988). Commonly, the 1755 Lisbon earthquake epicentre has been located 200 km southwest of San Vicente Cape (Fukao, 1973;Martinez Solares et al, 1979).…”

Section: Introductionmentioning

confidence: 99%

Holocene palaeotsunami catalogue of SW Iberia

Lario

Cardeña

Goy

et al. 2011

Quaternary International

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Many on-shore studies focused on high energy marine events occurred in the Gulf of Cadiz have been published since the 1990s. Most of the findings came from sedimentary, palaeontological and geomor phological records on estuaries, marshes, beach-barriers (spit-bars), and some coastal lowlands. Recent off-shore investigations in SW Iberia considered turbidite deposits as a proxy to recognise palae oearthquakes in this zone. The comparison of datasets from both on-shore and off-shore records indicate that at least five tsunami events generated by strong earthquakes affected this area during the last 7000 years, previous to the more recent and well-documented 1755 AD Lisbon earthquake tsunami event. The catalogue of Holocene palaeotsunami presented here is supported by geological and geomorphological evidences, but also for archaeoseismic and palaeoseismic evidence and written reports for the more recent events occurred during historical times. The recurrence interval for these catastrophic events can be bracketed between 1200 and 1500 years.

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“…The magnitudes provided by the Instituto Geografico Nacional (IGN, Madrid) are calculated in m bLg . The ones collected from publications (Buforn et al 1988a(Buforn et al ,b, 1995Grandin et al 2007) are expressed as surface wave magnitude, M s . We noticed that the magnitudes (m b ) provided by the IPMA are equals to the ones calculated by the IGN.…”

Section: Datamentioning

confidence: 99%

Intensity-distance attenuation laws for the Portugal mainland using intensity data points

Goff¹,

Borges²,

Bezzeghoud³

2014

Geophysical Journal International

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S U M M A R YIn this study, new intensity-distance attenuation law is presented, using directly the intensity observations, rather than the subjective, and sometimes controversial, isoseismal lines. This intensity-distance attenuation law is the only one defined for Portugal mainland, which is expressed as a function of magnitude. We computed this attenuation law using the slope and the intercept of the logarithmic regression of 25 events, with magnitudes between 4.4 and 6.2.Using the Bakun and Wentworth method (1997), this new attenuation law allows performing better results in the earthquake epicentral position and magnitude estimations of the 1909 Benavente event than the Atkinston and Boore attenuation law (1997). This law also gives good results in the study of site effects, presenting good matches between intensity residuals and geological structures where site effects are expected.

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Seismicity, source mechanisms and tectonics of the Azores-Gibraltar plate boundary

Cited by 252 publications

References 24 publications

Seismic swarms, fault plane solutions, and stress tensors for São Miguel Island central region (Azores)

Seismic swarms, fault plane solutions, and stress tensors for São Miguel Island central region (Azores)

Holocene palaeotsunami catalogue of SW Iberia

Intensity-distance attenuation laws for the Portugal mainland using intensity data points

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