This is our first report on Seulawah Agam, which has not erupted since a phreatic eruption in 1839. Beginning in April 2010, the seismicity increased at the volcano (table 1). However, visible signs of unrest were absent, although the volcano often is covered by fog.

Table 1. Types and numbers of volcanic earthquakes recorded at Seulawah Agam during April-August 2010. Background levels prior to increased April activity were not available. Courtesy of CVGHM.

On 1 September, based on the increase in seismicity, the Center of Volcanology and Geological Hazard Mitigation (CVGHM) raised the Alert Level to 2 (on a scale of 1-4) and restricted visitors from approaching the crater within a 3-km radius.

Geological Summary. Seulawah Agam, near the NW tip of Sumatra, is an extensively forested volcano with a small summit crater. It was constructed within the large Pleistocene Lam Teuba caldera, which also contains a smaller 6 x 8 caldera. The van Heutsz crater is an active fumarolic area on the NNE flank extending about 200 m downslope around 700 m elevation; it does not have the appearance of a volcanic crater. Additional geothermal areas are noted by Marwan et al. (2021). Sapper (1927) and Neumann van Padang (1951 CAVW) listed an explosive eruption in the early 16th century, and the CAVW also listed an eruption from the van Heutsz crater in 1839. However, Rock et al. (1982) found no evidence for historical eruptions. The Volcanological Survey of Indonesia also noted that although no reported eruptions have occurred from the main cone, the NNE-flank activity may have only been hydrothermal.

Information Contacts: Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://vsi.esdm.go.id/).