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TitleShallow earthquake inhibits unrest near Chiles-Cerro Negro volcanoes, Ecuador-Colombian border
AuthorEbmeier, S K; Elliott, J R; Nocquet, J M; Biggs, J; Mothes, P; Jarrin, P; Yépez, M; Aguaiza, S; Lundgren, P; Samsonov, S V
SourceEarth and Planetary Science Letters vol. 450, 2016 p. 283-291, https://doi.org/10.1016/j.epsl.2016.06.046 (Open Access)
Year2016
Alt SeriesNatural Resources Canada, Contribution Series 20170191
PublisherElsevier BV
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
AreaChiles-Cerro Negro; Ecuador; Colombia
Lat/Long WENS -78.0000 -77.9167 0.9167 0.7500
Subjectsearthquakes; faults; fault zones; volcanoes; geodesy; seismicity; remote sensing; faults, reverse; magmas; low-magnitude volcano-tectonic earthquakes; dextral oblique slip
Illustrationssatellite images; location maps; histograms; graphs; 3-D models
AbstractMagma 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 - 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.
GEOSCAN ID305950