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Shallow earthquake inhibits unrest near Chiles–Cerro Negro volcanoes, Ecuador–Colombian border

Research output: Contribution to journalArticle

  • Susanna K Ebmeier
  • John R Elliott
  • Jean Mathieu Nocquet
  • Juliet Biggs
  • Patricia Mothes
  • Paúl Jarrín
  • Marco Yépez
  • Santiago Aguaiza
  • Paul Lundgren
  • Sergey V. Samsonov
Original languageEnglish
Pages (from-to)283-291
Number of pages9
JournalEarth and Planetary Science Letters
Volume450
Early online date9 Jul 2016
DOIs
DateAccepted/In press - 23 Jun 2016
DateE-pub ahead of print - 9 Jul 2016
DatePublished (current) - 15 Sep 2016

Abstract

Magma movement or reservoir pressurisation can drive swarms of low-magnitude volcano-tectonic earthquakes, as well as occasional larger earthquakes (>M5) on local tectonic faults. Earthquakes >M5 near volcanoes are challenging to interpret in terms of evolving volcanic hazard, but are often associated with eruptions, and in some cases enhance the ascent of magma. We present geodetic observations from the first episode of unrest known to have occurred near Chiles and Cerro Negro de Mayasquer volcanoes on the Ecuador–Colombian border. A swarm of volcano-tectonic seismicity in October 2014 culminated in a Mw 5.6 earthquake south of the volcanoes. Satellite radar data spanning this earthquake detect displacements that are consistent with dextral oblique slip on a reverse fault at depths of 1.4–3.4 km within a SSW–NNE trending fault zone that last ruptured in 1886. GPS station measurements capture ∼20 days of uplift before the earthquake, probably originating from a pressure source ∼10–15 km south of Volcán Chiles, at depths exceeding 13 km. After the Mw 5.6 earthquake, uplift ceased and the rate of seismicity began to decrease. Potential mechanisms for this decline in activity include a decrease in the rate of movement of magma into the shallow crust, possibly caused by the restriction of fluid pathways. Our observations demonstrate that an earthquake triggered during volcanic unrest can inhibit magmatic processes, and have implications for the hazard interpretation of the interactions between earthquakes and volcanoes.

    Research areas

  • earthquake, GPS, InSAR, volcanic hazard

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  • Full-text PDF (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Elsevier at DOI: 10.1016/j.epsl.2016.06.046. Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 4.27 MB, PDF document

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