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

Abstract

The 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. The temperature monitoring in the lagoon is carried out continuously (MARN) and in the south east edge of the crater in a discrete way (UES). There is a seismic network (three stations) for monitoring the seismicity associated with the volcano. The results of this monitoring in the period from September 2006 to September 2017 present 2 periods with significant changes in temperature, Real-time Seismic Amplitude (RSAM), earthquakes associated with movement of fluids and color and level of the lagoon. The first change was observed in 2007, which ended with a phreatic eruption and a considerable reduction in the volume of the lagoon. The thermal anomaly in the south-east edge of the crater was 38 oC and in Laguna 61 oC, the RSAM presented significant changes. The second change occurred in 2017 with thermal anomalies of 52 oC at the south-east edge of the crater and 51 oC in the lagoon. In this period, the RSAM values did not show significant changes, only the earthquakes associated with the movement of fluids. According to these results, the temperature anomalies in the southeast sector of the volcano and the lagoon are sensitive to changes in RSAM, earthquakes associated with the movement of fluids and heat flow that the volcano presents.