| Title | Shallow earthquake inhibits unrest near Chiles-Cerro Negro volcanoes, Ecuador-Colombian border |
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| Author | Ebmeier, S K; Elliott, J R; Nocquet, J M; Biggs, J; Mothes, P; Jarrin, P; Yépez, M; Aguaiza, S; Lundgren, P; Samsonov, S V |
| Source | Earth and Planetary Science Letters vol. 450, 2016 p. 283-291, https://doi.org/10.1016/j.epsl.2016.06.046  Open Access |
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| Year | 2016 |
| Alt Series | Natural Resources Canada, Contribution Series 20170191 |
| Publisher | Elsevier BV |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Area | Chiles-Cerro Negro; Ecuador; Colombia |
| Lat/Long WENS | -78.0000 -77.9167 0.9167 0.7500 |
| Subjects | earthquakes; faults; fault zones; volcanoes; geodesy; seismicity; remote sensing; faults, reverse; magmas |
| Illustrations | satellite images; location maps; histograms; graphs; 3-D models |
| Released | 2016 09 01 |
| 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 - 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 ID | 305950 |
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