PVMBG reported that the number of deep volcanic earthquakes at Gamalama increased during 1-3 May. The seismic network recorded 11 deep volcanic earthquakes on 1 May and 14 on 2 May. During 0000-0900 on 3 May the network recorded five deep volcanic earthquakes, one shallow volcanic earthquake, five events indicating emissions, and one low-frequency earthquake. Diffuse white gas-and-steam plumes rose as high as 100 m; typically, these emissions rose as high as 300 m. PVMBG noted that the most likely hazard would be a phreatic event that could ejected material within the 1.5-km radius, though ash may be carried farther. The Alert Level remained at 2 (on a scale of 1-4); visitors and residents were warned not to approach the crater within a 1.5-km radius.

Geological Summary. Gamalama is a near-conical stratovolcano that comprises the entire island of Ternate off the western coast of Halmahera, and is one of Indonesia's most active volcanoes. The island was a major regional center in the Portuguese and Dutch spice trade for several centuries, which contributed to the extensive documentation of activity. Three cones, progressively younger to the north, form the summit. Several maars and vents define a rift zone, parallel to the Halmahera island arc, that cuts the volcano; the S-flank Ngade maar formed after about 14,500–13,000 cal. BP (Faral et al., 2022). Eruptions, recorded frequently since the 16th century, typically originated from the summit craters, although flank eruptions have occurred in 1763, 1770, 1775, and 1962-63.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)