Continuous and discrete thermal monitoring of Santa Ana volcano, period September 2006-September 2017, El Salvador, C. A.

Abstract

Santa Ana Volcano is located 15 kilometers southeast of the city of Santa Ana, in the western part of El Salvador with a height of 2,381 meters above sea level. At the bottom of the crater there is a lagoon with acidic water and a field of fumaroles. The last eruption occurred on October 1, 2005. Temperature monitoring in the lagoon is done continuously (MARN) and in the southeastern rim of the crater in a discrete manner (UES). There is a seismic network (three stations) to monitor the seismicity associated with the volcano. The results of this monitoring in the period from September 2006 to September 2017 presents 2 periods with significant changes in temperature, Real Time Seismic Amplitude (RSAM), earthquakes associated with fluid movement and color and lagoon level. The first change was observed in 2007, which concluded with a phreatic eruption and the considerable reduction of the lagoon volume. The thermal anomaly at the southeastern edge of the crater was 38 oC and in the lagoon 61 oC, the RSAM showed significant changes. The second change occurred in 2017 with thermal anomalies of 52 oC at the southeastern edge of the crater and 51 oC in the lagoon. In this period the RSAM values did not present significant changes, only the earthquakes associated with fluid movement. According to these results, the temperature anomalies in the southeastern sector of the volcano and the lagoon are sensitive to changes in RSAM, earthquakes associated with fluid movement and heat flow presented by the volcano.