Report for Piton de la Fournaise
OVPF reported that the eruption at Piton de la Fournaise continued during 10-16 January. Weather clouds often obscured views of the vent, though visual observations were made daily. Lava was sometimes ejected above the crater rim. The lava lake periodically rose and overflowed the cone during 10-13 January, sending flows down the flanks, and several breakouts of lava were visible on the flow field. The flow on the S margin of the field slowly advanced to the S wall of Enclos Fouqué. Activity decreased for a period of time during 14-15 January. Activity increased again during 15-16 January, though no overflows of the lake were recorded and lava was only periodically ejected above the rim. Some small vegetation fires were visible near the base of the caldera wall. Tremor decreased and the eruption ceased at 0210 on 17 January.

Report for Whakaari/White Island
On 18 January GeoNet reported results from an overflight of Whakaari/White Island the week before, noting a significant decrease of temperatures at the active vent area and a small decrease in gas emissions. Temperatures in the main vent area were as high as 191 degrees Celsius, a decrease from a high value of 516 measured in December. Gas emissions had slightly decreased since December; both sulfur dioxide and carbon dioxide gas emission rates were slightly below the 10-year average. Both the gas-emission and temperature data were consistent with a degassing magma body below the surface. Very minor ash emissions continued to be visible with deposits only extending around the active vents. The water in the lake had receded likely due to recent dry weather conditions. The Volcanic Alert Level remained at 2 and the Aviation Color Code remained at Yellow.

Report for Hunga Tonga-Hunga Ha'apai
Large eruptions at Hunga Tonga-Hunga Ha'apai on both 14 and 15 January produced plumes that reached the stratosphere and caused significant regional effects. Activity on the 14th apparently removed approximately the middle third of the island that had been expanded over the previous few weeks, revealed by a Planet Lab image acquired at 1525 on 15 January. About two hours after that image was taken an even stronger eruption produced a stratospheric plume seen in satellite images, sent pressure waves across the atmosphere, and caused tsunami that traversed the Pacific. Following these explosions, a Sentinel image acquired on 17 January showed that most of the previous combined island had been destroyed, leaving only small parts of the NE island of Hunga Tonga (200 m long) and the SW island of Hunga Ha'apai (700 m long) above the ocean surface.

A sub-aerial eruption that began at 0420 on 14 January produced mushroom-shaped ash, steam, and gas plumes that rose as high as 20 km (65,600 ft) a.s.l., into the stratosphere, and expanded radially at the top of the plume to 240 km in diameter, according to the Tonga Geological Services (TGS). Geologists observing from a boat around 1700-1830 in the afternoon noted that the plume was about 5 km wide at its base, with Surtseyan pulses ejecting dark dense material into the air, and pyroclastic flows expanding over the ocean. The eruption plume drifted over the island groups of Tongatapu, ‘Eua, Ha’apai, and Vava’u, carrying an estimated sulfur dioxide mass of 0.05 Tg (50,000 tonnes) based on satellite data. Sulfur odors were reported in Tongatapu (70 km S), near the capital on Motutapu Island, and on ‘Eua (106 km SSE). Ashfall was reported on many islands, including Fonoi and Mango (75 km ENE). The Tonga Meteorological Services (TMS) issued tsunami warnings for areas including ‘otu Mu’omu’a in Ha’apai (Nomuka, Mango, Fonoifua), ‘Atataa, ‘Eueiki, and Tongatapu mo ‘Eua. At 2000 on 14 January a tsunami with a height of 20 cm was recorded by the Nuku’olofa tide gauge. TMS warned residents to stay away from low-lying coastal areas, beaches, and harbors. The Wellington VAAC noted that the eruption was intermittent during 0043-0604 on 15 January; plumes rose to altitudes of 14 km (45,900 ft) a.s.l. The Global Lightning Detection Network (GLD360) ground-based network detected 191,309 lightning events during a 21-hour period (0334 on 14 January-0134 on 15 January), or up to 30,000 events per hour; for comparison, during 22-28 December 2018 the partial collapse eruption of Krakatau generated 337,000 events. TGS noted that at 0720 on 15 January an eruption lasting 10-15 minutes sent an ash plume to 14 km (45,900 ft) a.s.l. that drifted E.

A larger, submarine eruption began at 1700 on 15 January. According to news reports and social media posts, residents in Nuku'alofa (65 km S) heard multiple loud booms and saw a large expanding eruption plume that eventually covered all of the Tongan islands. According to the Wellington VAAC the plume had risen to 15.2 km (50,000 ft) a.s.l. by 1819; the top of the plume as seen in satellite images was at least 600 km in diameter by 1903. During 1719-2300 there were almost 400,000 lightning events recorded in the plume by the GLD360 network, with 200,000 of those during 1800-1900. By 0343 on 16 January the plume had risen to 19.2 km (63,000 ft) a.s.l. Analysis of other satellite datasets suggested that the plume may have risen to 30 km (98,400) a.s.l. The sulfur dioxide mass of the plume was 0.4 Tg (400,000 tonnes) derived from satellite-based estimates; the cloud drifted W consistent with stratospheric winds. Significant ashfall was reported on populated islands of Tonga, 70-100 km E. News articles noted that some residents had difficulty breathing from the ash in the air.

Most domestic and international communications on the islands were severed due to a break in an underwater cable, and ashfall has delayed both damage assessment and relief assistance. An update on 18 January from the Government of Tonga provided details about the eruption and its effects, noting that tsunami warnings issued after the eruption began had triggered evacuations. Tsunami waves 2-15 m high, based on a news article and the official report, arrived on the W coasts of the Tongatapu, ‘Eua, and Ha’apai islands, and three people in Tonga were confirmed to have died as a result, with many others injured. Extensive damage was reported on Mango, Fonoifua, and Nomuka islands, and on the W part of Tongatapu. Aerial surveillance by the New Zealand Defence Force’s showed brown, damaged vegetation and landscapes, debris, and modified coastlines with sediment-laden waters. The Government of Tonga also noted that communications to the outer islands were accomplished with a patrol boat on 17 January, and limited communication with residents of Vava’u and Ha’apai was possible the next day. Evacuation efforts were underway for some remote islands. Ashfall contaminated fresh water supplies, hindered sea transportation and harbor access, and caused flights to be cancelled. According to a news report the small island of Atata, near Nuku'alofa, had been completely submerged. Tsunami warnings were also issued in several other countries surrounding the Pacific Ocean. Several news sources reported flooding and damage caused by the tsunamis at locations as far away as Peru (over 10,000 km), where it caused two deaths. Warnings were issued for the N and E coasts of New Zealand’s North Island and the Chatham Islands; multiple boats were destroyed. Thousands in Japan evacuated after tsunami warnings, and the waves there reached 80 cm, disrupting train services, flights, and damaging harbors and boats. In Anchorage, Alaska, the US National Weather Service reported maximum waves heights of 20-100 cm on Alaskan coastlines, and along the British Columbia coast waves were 16-29 cm on 15 January.

The explosions produced multiple pressure (shock) waves that rippled through surrounding weather clouds, though the pressure wave from the largest explosion propagated across the planet. The sonic boom from this wave was heard at great distances, including in Fiji (about 500 km NW), within about two hours in New Zealand (1,600-2,000 km), and within about nine hours in Alaska, USA (9,370 km NE). The pressure wave was also recorded by infrasound and weather instruments worldwide as it circled the Earth, with instruments picking up the wave a second time as it arrived from the opposite direction. Very small perturbances in the ocean waves recorded in the Caribbean, which some referred to as meteotsunamis, were likely generated by atmospheric disturbances from the pressure waves after they passed over South America.

Report for Yasur
The Wellington VAAC reported that on 15 January intermittent low-level ash plumes from Yasur rose 1.5 km (5,000 ft) a.s.l. and drifted SE. Ashfall was reported in nearby villages. A Sentinel satellite image acquired that same day showed a strip of ash deposits in areas to the NW. Continuous, low-level ash plumes were visible in satellite and webcam images on 17 and 18 January rising to 1.5 km a.s.l. and drifting SE and W, respectively.

Report for Barren Island
The Darwin VAAC reported that during 1700-2200 on 8 January and 1200-1700 on 9 January ash plumes from Barren Island rose to 1.2 km (4,000 ft) a.s.l. and drifted W and WSW.

Report for Merapi
BPPTKG reported no significant morphological changes at Merapi’s lava domes, located just below the SW rim and in the summit crater, during 6-13 January. The intensity of the seismic signals remained at high levels. As many as 123 lava avalanches traveled a maximum of 2.2 km SW down the Bebeng drainage, and four pyroclastic flows traveled a maximum of 2.5 km SW. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-5 km away from the summit based on location.

Report for Semeru
PVMBG reported that the eruption at Semeru continued during 12-17 January. White steam plumes that were sometimes dense rose as high as 1 km above the summit almost daily, and crater incandescence was visible nightly. Incandescent avalanches traveled as far as 500 m down the Kobokan drainage on the SE flank during 11-12 January. White-and-gray ash plumes rose 300 m during 14-15 January. At 1020 on 16 January a collapse from the end of the active lava flow in the Kobokan drainage produced a pyroclastic flow, and an ash plume that rose 1.5 km and drifted N. An eruptive event at 0534 on 17 January generated an ash plume that a ground observer reported rising 400 m. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 500 m away from Kobokan drainages within 17 km of the summit, along with other drainages originating on Semeru, including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Report for Lewotolok
PVMBG reported that the eruption at Lewotolok continued during 11-16 January. Ash plumes rose as high as 700 m above the summit and drifted E, SE, and W during 11-14 January. Incandescent material ejected up to 300-700 m SE from the vent was accompanied by rumbling and banging noises. Eruption noises persisted through 16 January but weather prevented visual confirmation of activity during 15-16 January. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Report for Suwanosejima
JMA reported that incandescence at Suwanosejima's Ontake Crater was visible nightly during 10-17 January. There were 157 explosions recorded, producing ash plumes that rose as high as 2 km above the crater rim and ejected material up to 800 m away from the crater. Eruption sounds were heard in Toshima village (4 km SSW). Volcanologists observed ash-and-steam plumes rising from the crater during an overflight on 17 January. The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

Report for Aira
JMA reported that incandescence from Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible at night during 10-17 January. Seismic data showed a decreasing number of volcanic earthquakes. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Report for Karymsky
KVERT reported increased explosive activity at Karymsky and a thermal anomaly visible in satellite images during 7-8 and 11-12 January. Explosions during 11-13 January produced ash plumes that drifted almost 130 km in various directions. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Report for Sheveluch
KVERT reported that a thermal anomaly over Sheveluch was identified in satellite images during 8-14 January. Intense steam-and-gas emissions with ash were visible during 6-7 and 9-11 January; plumes rose as high as 5 km (16,400 ft) a.s.l. and drifted 175 km W. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Report for Semisopochnoi
AVO reported that low-level eruptive activity and elevated seismicity at Semisopochnoi's North Cerberus cone continued during 12-18 January. A small explosion was recorded by local seismic and infrasound sensors during 12-13 January. The weather was mostly cloudy, though low-level ash clouds were occasionally visible in webcam images during 12-15 January. Steam emissions were visible in 15-16 January webcam images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Report for Great Sitkin
AVO reported that slow lava effusion at Great Sitkin continued during 12-18 January, though cloudy conditions prevented satellite and webcam confirmation. Seismicity was very low and small events were occasionally recorded. Steam emissions were observed in webcam views during 14-15 January. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Report for Pavlof
AVO reported that elevated seismicity at Pavlof during 12-18 January was characterized by daily periods of tremor. Elevated surface temperatures consistent with lava effusion near the vent and the active lava flow on the SE flank were identified in satellite images almost daily; weather clouds prevented views for periods of time during 12-13 January. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Report for Kilauea
HVO reported that lava effusion resumed at the vent in the lower W wall of Kilauea’s Halema`uma`u Crater at around 1840 on 11 January. The level of the lava lake had increased 13 m by about 0300 on 12 January, slightly surpassing the level prior to the pause that began on 10 January; the lake has risen a total of 70 m since the beginning of the eruption. During 12-14 January the lake was active and lava oozed out along the crusted-over E margins. A surge in lava effusion at the vent was recorded at 0545 on 15 January, coincident with a peak in summit inflation. Effusion had paused by the afternoon, though minor activity at the vent on the N side of the spatter cone, minor overturns of the lake, and small oozes of lava at the lake’s margins persisted. The lake level dropped 10 m by the morning of 16 January. Small overturns of the crusted lake were visible during 16-17 January. By 18 January the lake was completely crusted over and a small wispy plume rose from the vent. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Report for Fuego
INSIVUMEH reported that 6-13 explosions per hour were recorded at Fuego during 12-18 January, generating ash plumes that rose as high as 1.1 km above the crater rim. The ash plumes mainly drifted 10-20 km S and SW causing almost daily ashfall in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Sangre de Cristo (8 km WSW), and La Rochela. Ash plumes drifted as far as 20 km E and NE during 14-16 January. Daily, periodic shock waves rattled structures in communities around the volcano. Block avalanches descended the flanks in all directions, but most commonly were visible in the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, and Las Lajas (SE) drainages, often reaching vegetated areas. Explosions ejected incandescent material up to 150-350 m above the summit during 12-16 January.

Report for Rincon de la Vieja
OVSICORI-UNA reported that at 0024 on 13 January a two-minute eruption was recorded at Rincón de la Vieja, though weather clouds prevented visual confirmation. Residents to the N heard the eruption and felt vibrations, and lahars were seen in the Rio Azul. Small eruptive events were recorded at 1153 on 15 January and 1243 on 18 January, but plumes were not visible due to weather clouds.

Report for Turrialba
OVSICORI-UNA reported that incandescence from Turrialba’s West Crater was visible overnight during 15-16 January. Eruptive events were recorded at 2126 and 2132 on 17 January; the second event was stronger and produced an ash-and-gas plume that rose 1 km above the crater. Ashfall and a sulfur odor were reported by residents in Coronado, Tres Rios (30 km SW), Alajuela (50 km W), and Santa Ana (46 km WSW). At 1115 on 18 January an eruptive event produced a plume that rose 300 m and drifted SW.

Report for Wolf
On 13 January IG reported that the eruption at Wolf was continuing, but at decreasing levels. Lava from at least three fissures had traveled about 16.5 km SE, and covered an estimated 7.4 square kilometers, but had not reached the coast. Daily counts of thermal anomalies were in the hundreds but had progressively decreased in quantity and intensity in recent days, interpreted as a decrease in the effusion rate and cooling flows. Notices of ash-and-gas plumes were issued by the Washington VAAC on 7-8 January, noting that plumes decreased from 2.6 km to 300 m above the vent. Additionally, sulfur dioxide emissions decreased from 60,000 tons per days recorded on 7 January to 8,100 tons per day on 12 January. Seismicity also trended downward.