STUDY AREAS

CANARY ISLANDS

Teide 2012 - Xavier de Bolós

The Canary Islands are one of the major active oceanic island groups of the world, where all islands except for La Gomera show Holocene volcanic activity. Historical volcanism (last 600 yrs) has been reported on the islands of La Palma (1430, 1585, 1646, 1677, 1712, 1949, 1971), Tenerife (1492, 1704, 1706, 1798, 1909), and Lanzarote (1730–1736, 1824), occurring the last one at El Hierro in 201. All these eruptions have been basaltic and characterised by emission of lava flows and construction of scoria cones. However, the active complex Teide-Pico Viejo on Tenerife, with nearly 20 Holocene eruptions, has the potential for larger and more destructive eruptions of more differentiated magmas.

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AZORES ISLANDS

Volcanism in Azores is tectonically controlled and occurs along major fault zones (fissural eruptive systems) or at fault intersections (central volcanoes). The geologic and landscape evolution of the islands results from the interaction between volcanic construction processes, surface faulting, mass wasting events, and erosion. In recent volcanically active areas, volcanic deposits hide or reduce the surface expression of faulting, and fault location is marked by alignment of cones and craters rows. When volcanic activity has decreased or stopped for some time (some thousand to tens of thousands of years), the faults present a clear geomorphic expression marked by fault scarps, tectonically controlled drainage, displaced cones, streams and interfluves, and sag ponds due to accumulated surface ruptures.

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The characteristics of recent volcanism (from post-settlement events and geological record) vary according to composition (basalt to trachyte) and eruptive environment (subaerial or submarine). Thus, eruptive styles range from basaltic hawaiian/strombolian to trachytic plinian/phreatoplinian caldera forming eruptions; littoral basaltic surtseyan eruptions are also common. The deadliest eruption was the 1630 Lagoa Seca (Furnas, São Miguel) event that claimed the life of 150 to 300 people.

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ICELAND

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Iceland is the largest volcanic island in the north Atlantic. Historic time on the island spans about 1100 years and during that time about 207 eruptions have occurred, both explosive and effusive. Two of the largest effusive eruptions on earth during the past 1100 years took place on Iceland, namely the eruption of Eldgjá in 934-938 and the eruption of Laki in 1783. Both eruptions caused global perturbation on the northern hemisphere. Explosive eruptions are also common in Iceland. Frequency of eruptions of the size VEI 5-6 are about 1 every 100 years, the last occurring in the year 1947. Thus, eruptions in Iceland are not only of concern to the local population, but also to the modern European population. Last eruption to have major effects on the European economy was the eruption of Eyjafjallajökull in 2010. Ongoing rifting event in the volcanic system of Bardarbunga is effusive, but volcanic gases released in the eruption where of concern in northern and central Europe. Local population of the island is about 300 thousand people. Most of them live around the capital area Reykjavik. Reykjavik is build at the edge of 4 volcanic systems building up the Reykjanes peninsula. For this project we focus on two main places, the greater Reykjavik area, last eruption occurring  in the 13th century and the ongoing Bardabunga volcanic system in the north and centre of Iceland.

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