PVMBG reported that the explosive eruption at Marapi continued during 10-17 January with daily dense ash plumes rising above the crater rim and drifting in various directions. White-and-gray ash plumes at 0900 and 0912 on 10 January rose 200-300 m and drifted NE and SE. Gray ash plumes rose 400-800 m at 0825, 0941, and 1133 on 11 January and drifted N, NE, E, and SE. Multiple gray ash plumes visible on 12 January (0640, 0936, 1042, 1058, 1217, 1824) rose as high as 1 km and drifted NE, E, and SE. White-and-gray ash plumes rose 200-600 m and drifted NE, SE, and SW during 13-15 January; rainy weather conditions prevented visual observations on 16 January. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the crater.

Geological Summary. Gunung Marapi, not to be confused with the better-known Merapi volcano on Java, is Sumatra's most active volcano. This massive complex stratovolcano rises 2,000 m above the Bukittinggi Plain in the Padang Highlands. A broad summit contains multiple partially overlapping summit craters constructed within the small 1.4-km-wide Bancah caldera. The summit craters are located along an ENE-WSW line, with volcanism migrating to the west. More than 50 eruptions, typically consisting of small-to-moderate explosive activity, have been recorded since the end of the 18th century; no lava flows outside the summit craters have been reported in historical time.

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