There are two main tectonic lineaments, with directions WNW–ESE and NNW–SSE (Fig. To the east of the ridge, the East Azores fracture Zone (EAFZ) marks the boundary between Eurasia and Africa [Krause and Watkins, 1970; Laughton and Whitmarsh, 1974]. the Azores triple junction (ATJ) and extends along or alongside the islands Graciosa, Terceira and São Miguel. Faial is the westernmost island of the central part of the archipelago (Fig. North of the East-Azores Fracture Zone the sediments are enriched in Ba which could be derived from different sources. The East Azores fracture Zone constitutes its southern boundary. seg- ments trending N—S and SW, act as major spreading 39 corresponded to a northward jump of the EU-NU plate boundary from the latitude of the East 40 Azores Fracture Zones, to the vicinity of the North Azores Fracture Zone, which would connect 41 Terceira Rift to the MAR (Searle, 1980). 2 A, 4 A and 8 A).The islands form the emerged part of the Azores micro-plateau, a triangular-shaped bathymetric shallow region bounded by three tectonic fracture systems that mark a triple junction that separates the North-American, … 2008). Several hypotheses were proposed for the plateau formation. (TDWG - level 3) East Aegean Is. The islands of the Azores Archipelago are located in the AP, with the … The AGFZ produced the large-magnitude 1755 Lisbon and 1969 Horseshoe earthquakes and, consequently, a number of large tsunamis. The CGFZ is the major fracture zone between Iceland and the Azores Islands. The Institute of Oceanographic Sciences map, contoured in metres, shows the islands of the Azores as the volcanic peaks of the worlds greatest Mountain range. The original location is thought to be the East Azores Fracture Zone (Gloria Fault) on the Nubian (Africa) Plate. The closer you get to the MAR the younger. 2008). For LVR widths of ~10 km the fracture network takes 1 - 6 Ma to develop, for the highest mantle viscosities of 5x10 21 - 5x10 22 Pa s. In the best-fit model, with a top mantle viscosity of 1x10 22 Pa s, the fracture network takes ~3 Ma to develop (Figure 4). The East Azores Fracture Zone (EAFZ) constitutes the western portion of the GF and is due south of the These anomalously shallow regions MAR Mid-Atlantic Ridge; EAFZ East Azores Fracture Zone; TR Terceira Rift; GF Gloria Fault ( in: Gaspar et al ., 1999). There is no or very little activity on the East Azores Fracture Zone (EAFS) see Figure 1. (TDWG - level 4) has preferred alternative East Aegean Is. Lots of quakes along the North Azores Fracture Zone as it approaches the junction with the East Azores Fracture Zone. and the Terceira Trough (Fig. (a) Princess Alice bank; (b) Azor bank; (c) Dom João de Castro bank; (d) West Graciosa Basin; (e) East Graciosa Basin; (f) North Hirondelle Basin; (g) South Hirondelle Basin; and (h) Povoação Basin. GeoNames. second zone with important seismic activity is located on NE–SW direction from the Ridge to Graciosa island through Pico and Faial islands continuing into the Terceira Ridge (Fig. Islands east of the Ridge, including Sao Miguel, are near the Azores fracture zone (called the Terceira Rift or Terceira Ridge by The Azores–Gibraltar Transform Fault (AGFZ), also called a fault zone and a fracture zone, is a major seismic zone in the Eastern Atlantic Ocean between the Azores and the Strait of Gibraltar. Fig.1 Geographical location of the Azores archipelago. The central and eastern group are located on a wide transtensional region, result ofthe obliqueseparationacrossthe Eurasian– African plate boundary passing through the Azores East Açores Fracture Zone (Fracture Zone) East Acton (Ward) East Adare Ridge (Ridge) East Adare Ridge (Ridge) replaced by East Adare Ridge : East Aegean Is. (b) 3D surface of the islands of the Azores Central Group. In this model, the two principal M.A.R. Atlantic Ocean. In the Atlantic Ocean most fracture zones originate from the Mid-Atlantic Ridge, which runs from north to south, and are therefore west to east oriented in general. The timing of predicted fracturing depends on model parameters. The yellow star indicates Pico Island. The white dashed line marks the Terceira Rift (TR) which comprises the islands of … Graciosa, Faial - Pico and S. Jorge alignments, and the East Azores Fracture (EAF) striking E-W to the south, bounding the western part of the Gloria Fault (GF) (Buforn et al, 1988; Luis et al, 1994). This is consistent with age determinations in the Azores indicating that the LVRs are … 1 c), which rises from a 10–15 Ma crust formed by Mid-Atlantic Ridge eruptions (Müller et al. ©2014. Faial is the westernmost island of the central part of the archipelago (Fig. This triangular volcanic plateau connects the Mid-Atlantic Ridge with the East Azores Fracture Zone, which runs west-to-east ultimately separating Africa and … Most fracture zones in the Pacific Ocean originate from large mid-ocean ridges (also called … (1998). These two prominent transform systems are the oceanic Azores-Gibraltar Fracture Zone, which includes the Gloria Fault and the SWIM Fault Zone, forming large parts of the in the central eastern Atlantic, and the submerged, continental NAF running through the Sea of … Zone; EAFZ: East Azores Fracture Zone. The chemical composition of the interstitial water shows that water advection is limited. Its spectacular topography has been formed by the geological forces that pull the American and African continental plates apart and allow fresh magma to rise. 1c), which rises from a 10– 15 Ma crust formed by Mid-Atlantic Ridge eruptions (Müller et al. 1a). and the Terceira Rift (TR) to the north-east. Looks like generally, the farther east you get, the older the island. Fault (GF) extends eastwardly from Santa Maria (Machado et al., 2008). extension of the East Azores Fracture Zone (EAFZ) to the west of the MAR, the FPFZ, displaying high seismicity and having clear bathymetric and magnetic expression, probably defines the location of the Azores triple point (Luis et al., 1994) at the intersection with the MAR. The Minou fracture zone is an active fault system and runs from the East to the West, North Kyushu, Southwest Japan (Chida, 1981). The second location was the Pico Fracture Zone which was active some 33 – 20 Ma. Further to the east, the plate boundary seems to partially follow the part of the East Azores fracture zone known as the Gloria fault, a 400 km long strikeslip fault with right-lateral sense of slip. The Azores straddle the Mid-Atlantic Ridge (fig. (a) Location map of the Azores archipelago and (b) main tectonic structures map of the Azores archipelago. On the active transform zones of the Mid Atlantic Ridge the earthquakes are from strike slip faulting but the main pattern in earthquakes on the ridge are normal faulting earthquakes in the divergent stress environment. 48 Azores, west of 25ºW there is no continuity between fracture and a marked topographic 49 linear depression that corresponds to the now called East Azores Fracture Zone (EAFZ) 50 strictly speaking, earlier interpreted by Morgan (1971) also as part of the plate 51 boundary. 1 a). The Minou fault is one of the components of the Imari-Matsuyama Line (IML) situated at the boundary between the northern and central parts of Kyushu Island and is considered as a source of the great earthquake that occurred in 679 AD ( Matsumura, 1990 ). 2 - Main tectonic structures in the Azores region. The GeoNames geographical database covers all countries and contains over eleven million placenames that are available for download free of charge. 1a), to the vicin-ity of the North Azores Fracture Zone, where it is located at present [17]. Figure 1. 1). It is the product of the complex interaction between the African, Eurasian, and Iberian plates. MAR refers to the Mid-Atlantic Ridge and EAFZ to the East Azores Fracture Zone. Both fracture zones strike 265° and are accompanied by large amplitude magnetic anomalies. Historic eruptions have occurred on five islands during the past 500 years (van Padang and others, 1967). the East Azores Fracture Zone (E.A.F.Z.) Bathymetry from Louren¸co et al. The Pico Island of Azores is the highest peak which rises 8,229.6m (27,000 feet) above the sea floor and 213.36m to 243.84 m above sea level. The Azores archipelago comprises nine islands, but only seven of them are located in the Central-East Atlantic, east of the Mid-Atlantic Ridge (see Figs. For some reason, seismicity since 1900 does not necessarily correspond with island age or volcanic activity. The Azores are nine islands that occupy a triple junction between the North American, African and Eurasian Plate. It is a spreading center bound by the Mid-Atlantic Ridge on the west and the Terceira Rift on the NE and the East Azores Fracture Zone to the SE. The main tectonic features that dominate the Azores region are the Mid-Atlantic Ridge (MAR), which crosses the archipelago between the islands of Faial and Flores with a general N-S direction, and the Azores-Gibraltar Fracture Zone that constitutes the Eurasian-Nubian plate boundary and extends from the MAR to the region of Gibraltar. From historical seismicity, we know that large shocks have occurred in the Azores tectonic structures: the East Azores Fracture Zone; the transtensionalfaultsystem,knownastheTerceiraRift; andtheMid-AtlanticRidge(Searle,1980;Vogt&Jung, 2004). stitute of Geosciences of the Azores, and consisted of geologic, geochemical, and geophysical inves tigations. The Azores are nine islands that occupy a triple junction between the North American, African and Eurasian Plate. It is a spreading center bound by the Mid-Atlantic Ridge on the west and the Terceira Rift on the NE and the East Azores Fracture Zone to the SE. EAFZ – East Azores Fracture Zone. The Charlie-Gibbs Fracture Zone (CGFZ) is the largest geological fault in the northern Mid-Atlantic Ridge between Iceland and the Azores. It offsets the ridge crest left laterally about 350 km bounded by 52° and 53°N. Legend: MAR—Mid-Atlantic Ridge; NAFZ—North Azores Fracture Zone; EAFZ—East Azores Fracture Zone and TR—Terceira Rift Figure 2. 2B), while the East Azores fracture zone is practically inactive. The original location is thought to be the East Azores Fracture Zone (Gloria Fault) on the Nubian (Africa) Plate. The second location was the Pico Fracture Zone which was active some 33 – 20 Ma. At this point, some authors believe the tectonics formed a short-lived Azores Micro Plate. Fig. It was first described by Johnson (1967) and later surveyed in some detail by Fleming (1970) who showed that it is comprised of two west-east lateral valleys, separated by a ca. The eastern part of the Terceira Ridge terminates against the East Azores fracture zone near 24øW (Figure 1). 1). Geomorphologic units of S˜ao Miguel Island. The Azores archipelago is located in on the Azores microplate at the triple junction between the North American, Eurasian, and African plates and is tectonically very active. East Azores Fracture Zone East Acores Fracture Zone,East Açores Fracture Zone: fracture zone: N 36° 30' 0'' W 26° 0' 0'' 140: Central Basin Trough The general strike in the area in between is 000° 015°. A first attempt describing in some detail the tectonic evolution of the area as a triple junction has been made by Krause and Watkins [3] . East Azores Fracture Zones (Fig. At this point, some authors believe the tectonics formed a short-lived Azores Micro Plate. The Azores archipelago in the Atlantic comprises nine volcanic islands which developed on a thick oceanic plateau close to the Triple Junction between the North American (Na), the Nubian (Nu), and the Eurasian (Eu) lithospheric plates. It is widely accepted, according to Vogt and Jung (2004), that the ATJ has made a jump from the intersection of East Azores Fracture Zone (EAFZ) and the MAR to its present location (Fig. 1). 11 Fig.1 Geographical location of the Azores archipelago. The area is dissected by the East Azores Fracture Zone at 36°55'N, identified as the active Eurasian-African plate boundary, and by another large, non-active fracture zone at 36°10'N. It contains numerous seamounts and seven of the Azores islands: Faial, Pico, S. Jorge, Graciosa and Terceira for the central group, S. Miguel and S. Maria in the eastern group. Journal of Geophysical Research: Solid Earth 10.1002/2014JB010982 MOREIRA ETAL. Previous work had shown that the Azorean archi pelago is located near the intersection of two tectonically active belts, the mid-Atlantic ridge and the east Azores fracture zone… Two elongated regions of anomalously shallow depths can be seen as V-shaped positive anomalies on the free-air satellite gravity map (Fig.
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