Closing crack earthquakes within the Krafla caldera, North Iceland

Zoë K. Mildon*, David J. Pugh, Jon Tarasewicz, Robert S. White, Bryndís Brandsdóttir

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

6 Citations (Scopus)


Moment tensor analysis with a Bayesian approach was used to analyse a non-double-couple (non-DC) earthquake (Mw ~ 1) with a high isotropic (implosive) component within the Krafla caldera, Iceland. We deduce that the earthquake was generated by a closing crack at depth. The event is well located, with high signal-to-noise ratio and shows dilatational P-wave first arrivals at all stations where the first arrival can be picked with confidence. Coverage of the focal sphere is comprehensive and the source mechanism stable across the full range of uncertainties. The non-DC event lies within a cluster of microseismic activity including many DC events. Hence, we conclude that it is a true non-DC closing crack earthquake as a result of geothermal utilization and observed magma chamber deflation in the region at present.

Original languageEnglish
Article numberggw325
Pages (from-to)1137-1141
Number of pages5
JournalGeophysical Journal International
Issue number2
Publication statusPublished - 1 Nov 2016

Bibliographical note

Publisher Copyright:
© The Authors 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society.

Other keywords

  • Earthquake source observations
  • Hydrothermal systems
  • Volcano seismology


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