Estructura tridimensional de velocidad de onda P para el volcán Galeras
DOI:
https://doi.org/10.32685/0120-1425/boletingeo.42.2008.13Keywords:
Seismic tomography, volcanic seismicity, volcanic activity, seismic model, Galeras volcano
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Abstract
A study of the inner structure of the Galeras Volcano was conducted using P-wave velocity first arrivals and 3D seismic tomography. Twenty four hundred high quality earthquakes with local magnitudes less than 2.0 were used in the study and a total of 14,500 P-wave arrivals were inverted.
Three anomalous zones with low P-velocity and two zones with high P-velocity were delimited. The low P-velocity zones (<-5%) are located to the east of the active crater at 3-4 km depth, to the west of the active crater at 4-6 km depth and beneath the active crater at 4-8 km depth with a large extension implying a similarly large magmatic feeding zone with small embedded bodies in different stages of crystallization. The high P-velocity zones (>5%) cover all of the volcanic edifice down to 4 km depth and at 10-12 km depth associated with the basement.
The high Vp zone at 0-4 km depth is associated with lava deposits at the surface and possibly with the Buesaco, Aranda and Romeral faults. The deeper zone to the west may be associated with an old magma body in the process of cooling, cry stallization and out-gassing. The low Vp zone to the west of the active crater at approximately 5 km depth may be related with a remnant magma body in the liquid or fluid stage. The low Vp zones delimited in this study suggest that the Galeras Volcano has a very large magmatic body with volumes nearing 20-25 km3.
