Report on San Miguel (El Salvador) — 1 January-7 January 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 1 January-7 January 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on San Miguel (El Salvador). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 1 January-7 January 2014. Smithsonian Institution and US Geological Survey.
13.434°N, 88.269°W; summit elev. 2130 m
All times are local (unless otherwise noted)
SNET reported that sulfur dioxide gas flux in tonnes per day from San Miguel was high: 2,200 on 31 December 2013, 1,740 on 1 January 2014, and 700 on 2 January. The report noted that the measurement on 2 January was likely low due to changes in wind patterns that day. During 1-2 January RSAM values ranged from 17 to 28 units. On 5 January gas plumes rose as high as 150 m above the crater. The next day light-gray gas plumes rose 200 m and drifted SW. RSAM values during 5-6 January were between 15 and 33 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.