The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, these notices are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of eruptions during the week, but rather a summary of activity that meet selected criteria. Carefully reviewed, detailed reports are published in the Bulletin of the Global Volcanism Network.

The Icelandic Meteorological Office (IMO) reported that an earthquake swarm began at Bárdarbunga at 0610 on 14 January in the NW part of the caldera. Initial estimates indicated that there were three earthquakes larger than an M 3 and one above an M 4; at 0705 the Aviation Color Code was raised to Yellow (the second lowest color on a four-color scale). The swarm continued though the morning and at 0805 a M 5 earthquake was detected. Seismicity began to decrease in intensity at around 0900 and continued at lower levels. The seismic network recorded about 130 earthquakes by 1418; seismicity continued overnight during 14-15 January. Similar activity occurred in 2014 before an effusive eruption that began after two weeks of unrest.

Source: Icelandic Meteorological Office (IMO)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that an eruptive event at Dempo was recorded at 0605 on 12 January and lasted 24 seconds. A white plume rose about 20 m above the summit and drifted N. A webcam image posted with the report showed black and gray material floating on the surface of the lake. The Alert Level remained at 2 (on a scale of 1-4), and the public were reminded to stay 1 km away from the crater and as far as 2 km on the N flank.

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

On 13 January the Icelandic Meteorological Office (IMO) reported that a gradual increase in seismic tremor at Grímsvötn had been detected over the previous few days, indicating the likely onset of jökulhlaup originating from the subglacial lake. Floodwaters typically emerge from the base of Skeiðarárjökull glacier, flowing into the Gígjukvísl river. On 15 January tremor recorded on the seismic station at Grímsfjall increased sharply, which is not unusual when a flooding event reaches peak discharge. The Aviation Color Code was raised to Yellow (the second level on a four-color scale) at 1319, reflecting the slight increase in the likelihood of an eruption being triggered by the flood. IMO noted that the last eruption following a flooding event was in 2004; since then there have been 13 jökulhlaups with no eruptions. The 2011 eruption was not preceded by a jökulhlaup.

Source: Icelandic Meteorological Office (IMO)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued during 8-15 January. Daily gray or white-and-gray ash plumes that were often dense generally rose as high as 2.5 km above the summit and drifted in multiple directions, though ash plumes occasionally rose higher. Webcam images posted with the reports often showed incandescence at the summit or being ejected above the summit of the inner active cone. During 10 and 13-14 January ash plumes rose up to 3 km above the summit. At 1935 on 11 January a dense gray ash plume rose 4 km above the summit and drifted W and, according to BNPB, incandescent lava was ejected as high as 2 km above the summit. The event lasted for three minutes and five seconds based on seismic data. At 0711 on 15 January a dense ash plume rose 4 km above the summit and drifted W and a pyroclastic flow traveled 500 m N. Booming and rumbling sounds were heard at the Ibu Observation Post (9 km W). In a press release PVMBG noted that taller ash plumes, 3-4 km above the summit, had become more frequent during 1-15 January. Additionally, the number of shallow volcanic earthquakes increased, and deformation data showed inflation on 6 and 13 January. The Alert Level was raised to 4 (the highest level on a four-level scale) at 1000 on 15 January and the public was advised to stay 5 km away from the active crater and 6 km away from the N crater wall opening.

Sources: Badan Nacional Penanggulangan Bencana (BNPB) ,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

The Hawaiian Volcano Observatory (HVO) reported that incandescence and low-level spattering from two vents located at the SW margin of Halema?uma?u Crater within Kilauea?s Kaluapele summit caldera were visible during 8-14 January. Incandescence at the craters was visible during 8-10 January. An automatic laser rangefinder, pointing at an area of the crater floor from a few hundred meters N of the vents, measured about 4 m of subsidence during the first few days after fountaining stopped on 3 January, and since then the level of the floor has mostly remained stable. Monitoring data showed that the summit was slowly inflating, indicating that magma was accumulating below the summit area. During an overflight on 10 January scientists observed active but slow-moving lava within the vents just a few meters below the crater floor. After sunset on 11 January very minor spattering within the N eruptive vent was visible in livestream camera views. The vigor of the spattering was variable through the night with the peak phase occurring just before 0400 on 12 January. Spatter was ejected no higher than 5-20 m and remained within the vent. Intermittent spattering continued during the morning but was then obscured by daylight. Later that evening visitors to Hawai?i Volcanoes National Park reported seeing low-level spattering at the N vent. Spattering was not discernible in the webcam feed, so the spatter was likely not ejected more than 5 m and remained in the vent. Incandescence was visible from both vents during the morning of 13 January; it was unclear if spattering continued. Three periods of localized crater floor subsidence, each lasting 60-90 minutes, were recorded by laser rangefinder at 0745, 1345, and 1730, and were followed by a refilling of magma beneath the crust. Incandescence from the N vent was visible in webcam images overnight during 13-14 January. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

The Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA) reported that bubbling in the lake at Poás, visible during 1400-1700 on 7 January, was associated with a tremor signal. Convecting water over the Boca A and Boca C vents was visible during 13-14 January.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)

The Instituto Nicaragüense de Estudios Territoriales (INETER) reported that multiple gas-and-steam emissions were observed rising from Telica during 11-13 January and some of those emissions contained ash. Distinct plumes reported to contain ash rose 150 m above the crater rim on 13 January that blew to the NW at 1115, then to the N and SW at 1640. From 2000 on 13 January to 0800 on 14 January there were 25 gas-and-ash explosions; four of the explosions that occurred during 2214-2355 on 13 January ejected ballistics about 50 m above the crater rim and onto the flanks. Through 1000 on 14 January there were 91 explosions recorded, producing gas, steam, and ash plumes that rose no higher than 200 m above the crater.

Source: Instituto Nicaragüense de Estudios Territoriales (INETER)

On 13 January GeoNet reported that emissions from Whakaari/White Island during the previous 2-3 weeks were characterized as passive, weak-to-moderate, gas-and-steam plumes that sometimes contained ash. The plumes were visible in images from satellite and webcams (at Whakatane and Te Kaha), and during clearer weather conditions a larger plume was occasionally visible from the Bay of Plenty. The New Zealand Met Service also detected ash in the plumes using satellite images on some of the days. According to the Wellington VAAC low-level emissions that contained ash rose 0.6-1 km (2,000-3,000 ft) a.s.l. and drifted N, SW, and S during 9-11 and 13-14 January. GeoNet noted that the ash in the plumes created hazy conditions downwind of the island. The recent activity was consistent with moderate-to-heightened unrest, therefore the Volcanic Alert Level remained at 2 (on a scale of 0-5). At 1230 on 13 January the Aviation Color Code was raised to Orange (the second highest level on a four-color scale). GeoNet stated that the Alert Levels were reflective of the current level of activity, but there was uncertainty due to the current lack of consistent, usable, real-time monitoring data; GeoNet relies on remote cameras and satellite images to monitor Whakaari.

Sources: GeoNet ,Wellington Volcanic Ash Advisory Center (VAAC)

The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 6-13 January. Nightly crater incandescence was visible in webcam images. Explosions at 1451 and 1913 on 6 January, at 1946 and 2225 on 7 January, at 0516 on 8 January, and at 0449 on 12 January produced ash plumes that rose 0.9-1.5 km above the crater rim and drifted SE. All of the explosions, except for those at 1451 on 6 January and at 1946 on 7 January, ejected large blocks 300-1,100 m above the crater rim. An eruptive event at 0541 on 12 January produced an ash plume that rose 1.2 km above the crater rim and drifted SE. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to stay 1 km away from both craters.

Source: Japan Meteorological Agency (JMA)

The Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) reported that eruptive activity continued at Fuego during 7-14 January. Daily explosions were recorded by the seismic network at rates of 5-13 per hour. The explosions generated gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted 10-30 km N, NW, W, and SW. Weak-to-moderate rumbling sounds and shock waves from explosions were occasionally reported; the shock waves rattled nearby structures during 11-12 January. The explosions also generated block avalanches around the crater that sometimes descended the Las Lajas (SE), Seca (W), Taniluya (SSW), Honda (E), El Jute (ESE), and Ceniza (SSW) drainages and sometimes reached vegetated areas. On most days, explosions ejected incandescent material 100-200 m above the summit and showered the upper flanks with incandescent material. Ashfall was reported in Panimache I and II (8 km SW), Morelia (10 km SW), Santa Sofia (12 km SW), El Porvenir (11 km SW), Finca Palo Verde (10 km WSW), Yepocapa (12 km SW), Sangre de Cristo (8 km W), and other nearby communities during 8-9 January, and in Yepocapa, Quisaché (8 km NW), La Soledad (11 km N), Parramos (18 km NNE), and surrounding areas during 10-11 January; ashfall was forecasted for areas downwind on the other days.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick lava flow in Great Sitkin?s summit crater during 7-14 January. The local seismic network continued to detect small earthquakes associated with the ongoing eruption. Nothing notable was identified in cloudy satellite and webcam images; though during the morning of 12 January diffuse steaming at the summit was identified in a satellite image. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

The Tonga Geological Services reported that analysis of satellite images showed no size changes at Home Reef during 2-12 January. A thermal anomaly persisted through 14 January. The Maritime Alert Level remained at Orange (the third level on a four-level scale), and mariners were advised to stay at least 2 nautical miles (3.7 km) away from the island. The Aviation Color Code remained at Yellow (the second level on a four-level scale), and the Alert Level for residents of Vava?u and Ha?apai remained at Green (the first level on a four-level scale).

Source: Tonga Geological Services, Government of Tonga