According to SNET, the Ministerio de Medio Ambiente y Recursos Naturales (MARN) reported that during 22-23 May heavy rains at San Miguel caused lahars that originated from the upper part of the volcano and were heard by residents. Seismicity and gas output both remained high. Gas plumes rose 300 m and drifted W; the plumes were different colors and suggested that fine material was being carried out of the crater.

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)