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Los eventos sísmicos tienen una gran variedad de clases, las cuales se manifiestan en mayor o menor frecuencia dependiendo del volcán en estudio. En este artículo se presenta un método de clasificación de eventos sísmicos del volcán Nevado del Ruiz mediante reglas fijas de combinación de clasificadores, buscando de esta manera explotar la multiplicidad de datos de los registros del Observatorio Vulcanológico y Sismológico de Manizales, provenientes de las diversas estaciones de monitoreo. El objetivo es aprovechar los múltiples conjuntos de entrenamiento que se pueden obtener a partir de eventos que fueron registrados simultáneamente en varias estaciones, lo cual garantiza la independencia de datos y, por lo tanto, el aumento del desempeño de clasificadores combinados bajo las reglas de producto y suma.

An analysis of the seismic activity for volcano-tectonic earthquake (VT) swarms zones at Nevado del Ruiz Volcano (NRV) was carried out for the interval 1985- 2002, which is the most seismic active period at NRV until now (2010). The swarm-like seismicity of NRV was frequently concentrated in very well defined clusters around the volcano. The seismic swarm zone located at the active crater was the most active during the entire time. The seismic swarm zone located to the west of the volcano suggested some relationship with the volcanic crises. It was active before and after the two eruptions occurred in November 1985 and September 1989. It is believed that this seismic activity may be used as a monitoring tool of volcanic activity. For each seismic swarm zone the Vp/Vs ratio was also calculated by grouping of earthquakes and stations. It was found that each seismic swarm zone had a distinct Vp/Vs ratio with respect to the others, except for the crater and west swarm zones, which had the same value. The average Vp/Vs ratios for the seismic swarm zones located at the active crater and to the west of the volcano are about 6-7% lower than that for the north swarm zone, and about 3% lower than that for the south swarm zone. We suggest that the reduction of the Vp/Vs ratio is due to degassing phenomena inside the central and western earthquake swarm zones, or due to the presence of microcracks inside the volcano. This supposition is in agreement with other studies of geophysics, geochemistry and drilling surveys carried out at NRV. [ABSTRACT FROM AUTHOR]