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Report on San Miguel (El Salvador) — 28 February-6 March 2018


San Miguel

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 28 February-6 March 2018
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2018. Report on San Miguel (El Salvador) (Sennert, S, ed.). Weekly Volcanic Activity Report, 28 February-6 March 2018. Smithsonian Institution and US Geological Survey.

Weekly Report (28 February-6 March 2018)

San Miguel

El Salvador

13.434°N, 88.269°W; summit elev. 2130 m

All times are local (unless otherwise noted)


On 2 March SNET reported that gas plumes rose as high as 400 m above San Miguel’s crater rim during the previous week. Ash was in the emissions on 24, 26, and 28 February, and 1 March. RSAM values fluctuated between 70 and 179 units (normal values are 50-150 units) during 1-2 March. At 2200 on 5 March seismic amplitude began to increase, with RSAM values rising to 318 units by 0600 on 6 March. A webcam recorded minor gas emission during 5-6 March.

Geological Summary. The symmetrical cone of San Miguel, one of the most active volcanoes in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. A broad, deep, crater complex that has been frequently modified by eruptions recorded since the early 16th century caps the truncated unvegetated summit, also known locally as Chaparrastique. Flanks eruptions of the basaltic-andesitic volcano have produced many lava flows, including several during the 17th-19th centuries that extended to the N, NE, and SE. The SE-flank flows are the largest and form broad, sparsely vegetated lava fields crossed by highways and a railroad skirting the base of the volcano. Flank vent locations have migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.

Source: Servicio Nacional de Estudios Territoriales (SNET)