Chapter 10 Distribution and significance of basaltic eruptive centres: São Miguel, Azores

Self Cite

São Miguel Island comprises five active volcanic systems, including three central volcanoes with calderas and two basaltic fissure systems. Volcanic eruptions in São Miguel are of basaltic and trachytic nature (s.l.), including Hawaiian, Strombolian, sub-Plinian, Plinian and Vulcanian events, the more explosive ones frequently including hydromagmatic phases. Large Plinian eruptions are related to caldera-forming events that occurred in the past. With reference to the Fogo A stratigraphic marker, a total of 73 individual volcanic eruptions have been identified in the last 5 ka, giving a recurrence interval of 68.5 years. Taking into account that only six events have occurred in historical times, the recurrence interval increases to 95 years and, clearly, a future event is overdue because the most recent eruption occurred in 1652. It should be noted, however, that some volcanic eruptions in the past have occurred in clusters.The eruptive frequencies of the last 5 ka of activity have been determined for all types of eruptions and related hazards, including lava flows, pyroclastic falls, pyroclastic density currents (PDCs) and lahars. The areas susceptible to volcanic products have been mapped and modelled under different eruptive conditions. † Deceased 19 May 2012.

Section: Styles Of Activity and Eruptive Frequencymentioning

confidence: 99%

Chapter 12 Eruptive frequency and volcanic hazards zonation in São Miguel Island, Azores

Gaspar

Guest

Queiroz

et al. 2015

Self Cite

“…Picos Fissural Volcanic System (Ferreira 2000;Ferreira et al 2015) is the youngest geological unit of São Miguel and is located between Sete Cidades and Fogo central volcanoes (Fig. 6.2).…”

Section: Picos Fissural Volcanic Systemmentioning

confidence: 99%

Chapter 6 Volcano-tectonic structures of São Miguel Island, Azores

Carmo

Madeira

Ferreira

et al. 2015

Self Cite

The Azores archipelago is located at the triple junction between the Eurasia, Nubia and North America lithospheric plates. São Miguel Island, situated at the southeastern part of the western segment of the Azores-Gibraltar Fracture Zone, presents an east-west elongated shape, comprising three quiescent central volcanoes with summit calderas linked by zones of fissure volcanism. The eastern part of the island is older and inactive. Active faulting is represented by prominent fault scarps that constitute important extensional structures, or by linear volcanic structures in fissural volcanic zones, with a dominant NW-SE to WNW-ESE trend. Although less frequent, there are also NNW-SSE to north-south, NE-SW and east-west faults, reflected by some volcanic alignments and linear segments of the drainage system and sea cliffs. The geometric and kinematic data are in agreement with that observed in the rest of the archipelago. However, at eastern São Miguel Island data indicate two distinct groups of conjugated faults characterized by three-dimensional strain: NW-SE to WNW-ESE normal dextral structures are conjugated with NNW-SSE normal left-lateral faults and NW-SE to WNW-ESE normal left-lateral faults are conjugated with NE-SW normal dextral structures, showing the presence of two different stress fields separated in time.

“…24-27;Wisner et al 2004, pp. These are discussed in other chapters in this volume (Ferreira et al 2015;Gaspar et al 2015a, b;Queiroz et al 2015;Wallenstein et al 2015). In recent years considerable progress has been made in researching a wide variety of extreme events on São Miguel.…”

mentioning

confidence: 90%

Chapter 16 Volcanic hazard vulnerability on São Miguel Island, Azores

Wallenstein

Chester

Coutinho

et al. 2015

In recent years much progress has been made in researching a wide variety of extreme events on São Miguel. In addition there are a number of volcano-related risks that impact upon the people of São Miguel. Some of these may occur both before and during volcanic emergencies (e.g. earthquakes), whilst others render São Miguel dangerous even when its volcanoes are not erupting (e.g. flooding, landslides, tsunamis and health impacts, especially the effects of CO 2 seepage into dwellings). In this chapter we first define what vulnerability means to the people of São Miguel, and relate this to the cultural and economic characteristics of the island. The following aspects of vulnerability are discussed: (a) physical (i.e. housing, settlement and the characteristics of evacuation routes and plans); (b) demographic and economic; and (c) social and cultural and perceptual (i.e. whether people have an accurate cognition of risk). Particular areas of concern relate to housing: the identification of isolated dwellings that would be difficult to evacuate; the vulnerability/ resilience of evacuation routes following recent infrastructure improvements; characteristics of the island's transient population; management of livestock under emergency conditions; local leadership roles; and educational outreach.