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Precise relocation of volcanic-tectonic events recorded during the 2017-2019 swarm below the Chiles - Cerro Negro volcanic complex (Ecuador - Colombia)

Andrea Córdova1, Jean Battaglia2, Laurence Audin3, Silvana Hidalgo1

  • Affiliations: 1Instituto Geofísico - Escuela Politécnica Nacional, Quito, Ecuador 2Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Clermont-Ferrand, France. 3Université Grenoble - Alpes, CNRS, IRD, Grenoble, France

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 134

  • Programme No: 2.1.44

  • Theme 2 > Session 1

Abstract

The Chiles - Cerro Negro volcanic complex (CCNVC), located in the Western Cordillera, on the Ecuador - Colombia border, has presented an increase in its seismic activity levels since 2013. This activity has been characterized by the presence of intense swarms of volcano-tectonic events. To examine the seismicity in the CCNVC area, we took as a sample, the swarm recorded between 2017 and 2019. As the rate of earthquakes in the area is high, we used automatic algorithms for the detection and picking of transient events, which were subsequently correlated with each other to group them within families of similar events using cross-correlation. This technique allowed us to locate approximately 43000 earthquakes grouped in 30 families. These preliminary locations allowed to select the best quality events and pipe them to a relocation process using double difference techniques. The precise relocations obtained for the first 5 families show complex sub-horizontal structures, with shallow depths between 0 to 2 km b.s.l, and reveal a lack of seismicity below 10 km below the edges. This could suggest the presence of a hot and ductile crust or a diffuse magma storage region. Besides, the spatio-temporal evolution of the seismicity of these families show horizontal migrations, which suggests changes in pore pressure in the subsurface, under the southern flank of the Chiles volcano, due to new pulses of volcanic activity in the area.