Low-frequency earthquakes at the Torfajokull Volcano, south Iceland

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doi: 10.1016/j.jvolgeores.2005.10.012
Authors:Soosalu, Heidi; Lippitsch, Regina; Einarsson, P.
Author Affiliations:Primary:
University of Iceland, Nordic Volcanological Center, Reyjavik, Iceland
Other:
University of Cambridge, United Kingdom
Volume Title:Journal of Volcanology and Geothermal Research
Source:Journal of Volcanology and Geothermal Research, 153(3-4), p.187-199. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-0273
Publication Date:2006
Note:In English. Based on Publisher-supplied data
Summary:Torfajokull is a large rhyolitic volcanic edifice with a 12-km-diameter caldera and abundant high-temperature geothermal activity. It is located in the neovolcanic zone in south Iceland, at the junction of the eastern rift zone and a transform zone with the intraplate volcanic flank zone of south Iceland. The latest eruption at Torfajokull occurred about 500 years ago. Torfajokull is a source of persistent small-scale seismicity, where two types of earthquakes occur. High-frequency events are concentrated in the western part of the caldera and low-frequency events cluster in the south. Small low-frequency earthquakes have been observed at Torfajokull since the installation of a local analogue seismograph station in 1985. They typically occur in swarms; up to 300 earthquakes per day have been observed. The low-frequency events have a frequency content of about 1-3 Hz, and are difficult to locate, because of the emergent nature of their phases. The 160 events located during the years 1994-2000 using the permanent Icelandic seismic network cluster in the southern part of the Torfajokull caldera. A closer study of low-frequency events was carried out between May and October 2002, with a dense network of twenty Guralp 6TD broadband seismometers in the Torfajokull area. No distinct swarm activity was observed during this period, but small low-frequency events occurred almost on a daily basis. About 330 low-frequency events were detected during the study period. They are located in the southern part of the caldera, between two small glaciers. Areas of intensive geothermal activity surround the cluster of low-frequency events. It is argued that these earthquakes are associated with active magma in the south part of the Torfajokull caldera, possibly a rising cryptodome. Abstract Copyright (2006) Elsevier, B.V.
Sections:Petrology; Physical properties of rocks and minerals
Subsections:Volcanology
Subjects:Calderas; Domes; Earthquakes; Geologic hazards; Magmas; Rhyolitic composition; Volcanic earthquakes; Volcanic features; Volcanoes; Europe; Iceland; Western Europe; Torfajokull
Abstract Numbers:06M/2630
Record ID:2007063998
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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