In January, activity originating from Arenal’s Crater C consisted of gas emissions, sporadic Strombolian eruptions, and occasional avalanches from lava-flow fronts that traveled down the S flanks. Blocks from the lava-flow fronts periodically reached vegetation and started small fires. Volcanic activity was at relatively low levels and few eruptions occurred. Acid rain and small amounts of ejected pyroclastic material affected the NE and SE flanks. Eruptions produced ash plumes that rose about 2.2 km (7,100 ft) a.s.l. Small avalanches of volcanic material traveled down several ravines. Crater D showed only fumarolic activity.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”