Report on San Miguel (El Salvador) — 10 February-16 February 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 10 February-16 February 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on San Miguel (El Salvador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 10 February-16 February 2021. Smithsonian Institution and US Geological Survey.
13.434°N, 88.269°W; summit elev. 2130 m
All times are local (unless otherwise noted)
SNET stated that San Miguel’s seismic network recorded long-lasting and continuous periods of volcanic tremor that began on 7 February and continued through 14 February. Discrete earthquakes from minor rock fracturing were also detected. RSAM values fluctuated between 25 and 75 units, below normal values around 150 units.
Geologic Background. The symmetrical cone of San Miguel volcano, one of the most active in El Salvador, rises from near sea level to form one of the country's most prominent landmarks. The unvegetated summit rises above slopes draped with coffee plantations. A broad, deep crater complex that has been frequently modified by historical eruptions (recorded since the early 16th century) caps the truncated summit, also known locally as Chaparrastique. Radial fissures on the flanks of the basaltic-andesitic volcano have fed a series of historical lava flows, including several erupted during the 17th-19th centuries that reached beyond the base of the volcano on the N, NE, and SE sides. 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. The location of flank vents has migrated higher on the edifice during historical time, and the most recent activity has consisted of minor ash eruptions from the summit crater.