On 10 May around 1700 an eruption began at Anatahan, a volcanic island which has had no historically documented eruptions. Scientists on a small ship about 10 km away saw an ash plume that eventually rose to ~12 km a.s.l. The eruption occurred primarily from Anatahan's eastern crater and observers did not see lava flows. No precursory activity was recorded (the island of Anatahan is uninhabited and lacks working seismometers) and no signs of the impending eruption were seen by scientists who visited the island on 6 May.

According to the Washington VAAC, an ash cloud was visible on satellite imagery beginning around 1730 on 10 May. The next day around 0655 ash was seen moving in three different directions; WNW at a height around 5.5 km a.s.l., SW around 8.5 km a.s.l., and two separate and smaller ash plumes were drifting SE at heights around 13.4 km a.s.l.

Local authorities issued a special advisory on 11 May stating that ". . . the general public especially fisherman, tour operators and commercial pilots are advised to stay away from the island of Anatahan until further notice from the Office of Emergency Management." As of 13 May ash emissions continued and a hot spot was visible on satellite imagery. Residents of the small island of Anatahan (part of the United States Commonwealth of the Northern Mariana Islands) were evacuated in 1990 after a shallow earthquake swarm. The most recent reported seismicity occurred in 1993.

Sources: The Margins Mariana Subduction Factory Imaging Project Research Team (from Washington University, St. Louis; Scripps Inst. of Oceanography; and CNMI Emergency Management Office), Marianas Variety, Voice of America News, US Geological Survey Hawaiian Volcano Observatory (HVO), Washington Volcanic Ash Advisory Center (VAAC)

Heavy rainfall (200 mm in less than 24 hours) at Reventador on 6 May led to the remobilization of ash that was deposited on the volcano's flanks during the November 2002 eruption. Lahars traveled down the volcano's SE flank via Marker and Reventador gorges. According to IG, seismic signals indicated that lahars occurred in seven main pulses, with the longest pulse lasting ~2 hours. Lahars crushed a portion of the sole petroleum pipeline in Ecuador, located on the volcano's SE flank, and dragged it 22 m. According to news reports, about 5,600 barrels of crude oil escaped the damaged pipeline and entered Reventador River. News reports also stated that a large area of the Amazon jungle was polluted. Lahars also destroyed a bridge and blocked a highway that crosses the Amazon.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), IRIB News, Reuters, El Comercio

The eruption that began at Chikurachki on 18 April continued through 9 May. On 1 May ash fell in the town of Severo-Kurilsk, ~60 km from the volcano. On 3 May weak fumarolic activity was seen, and on 5 May an ash-rich plume was observed extending to the NW. Chikurachki was at Concern Color Code Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

During 6-11 May, several ash emissions occurred at Colima. Based on information from the Mexico City MWO, the Washington VAAC reported that the largest eruption during the report period occurred on 6 May and produced an ash cloud to ~6 km a.s.l. In addition, lava flows traveled down the volcano's S flank.

Source: Washington Volcanic Ash Advisory Center (VAAC)

On 22 April at 1802 an ash explosion occurred at Karangetang that was accompanied by the ejection of incandescent volcanic material. The resultant ash column rose to ~1,750 m above the volcano, and incandescent material was ejected to ~750 m above the volcano. Ash was deposited on the volcano's W slope, including in the villages of Lehi, Mini, Kinali, and Hiung. The explosion was followed by lava avalanches to the W and S and pyroclastic flows toward Batang River to a runout distance of 2,250 m. Another explosion occurred on 24 April that produced an ash cloud to ~750 m above the volcano. Generally, during 21 April to 4 May, low-level ash plumes rose above South Crater, and glowing was seen up to 25 m above the crater. Karangetang remained at Alert Level 3 (on a scale of 1-4).

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

During 2-9 May, intermittent explosive eruptive activity continued at Karymsky and seismicity was at background levels. Karymsky remained at Concern Color Code Yellow.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Lava continued to flow down Kīlauea's S flank, with small surface flows visible. On 12 May lava began to enter the sea again at the West Highcastle lava delta. Generally, seismicity was at normal to below normal levels, with very few earthquakes. Volcanic tremor at Puʻu ʻŌʻō remained at moderate-to-high levels.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

On 6 May at 0721 a small explosion occurred at Mayon. The brownish ash-and-steam column produced from the explosion rose about 450 m above Mayon's summit crater and drifted SW. No significant seismicity was recorded prior to the explosion. Electronic tiltmeters on the N and S flanks continued to show inflation of the volcanic edifice. Likewise, a leveling survey conducted on 24 April showed a general inflation of the N flank. Mayon remained at Alert Level 1 (on a scale of 0-5). PHIVOLCS emphasized that the 6-km-radius Permanent Danger Zone remained in effect.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

On 2 and 3 May a dense ash plume was visible from the town of Goma rising above Nyiragongo. Continuous ash fall occurred in many villages close to the volcano, and permanent tremor and long-period earthquakes were recorded. During a visit to the volcano during 6 and 7 May scientists saw that the lava pool in the crater was very active, with violent gas outbursts, projection of spatter and surges, and lava splashing the walls of the pit. Occasionally, large (~ 50 m high) flames were hurled from the vents. SO₂ emission rates were relatively high during 1-6 May, with the largest emission (~50,000 tons) occurring on 3 May. According to the Toulouse VAAC, a possible ash cloud was visible on satellite imagery on 12 May that remained at a height below 6 km.

Sources: Observatoire Volcanologique de Goma (OVG), Toulouse Volcanic Ash Advisory Centre (VAAC)

During 7-10 May, moderate emissions of mainly gas and steam occurred at Popocatépetl. In addition, isolated episodes of low-amplitude harmonic tremor were occasionally recorded. No signs of a new lava dome were seen during a flight over the volcano on 20 April.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

During 25 April to about 6 May, volcanic activity was at moderate levels at Soufrière Hills, with pyroclastic flows and rockfalls mainly traveling NE. During about 6-9 May there was a general increase in the size of pyroclastic flows, some of which were among the largest and most energetic seen for several months. Most flowed along the N side of the Tar River Valley, and a few also flowed into White's and Tuitt's ghauts. Sulfur-dioxide emission rates were low during about the first week of the report period, then fluctuated from moderate to high levels. The Washington VAAC reported that low-level ash plumes were sometimes visible on satellite imagery.

Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)

Based on information from IG, the Washington VAAC reported that a small explosion at Tungurahua on 6 May produced a cloud composed mainly of gas, with some ash. The cloud drifted W and seismic activity decreased after the explosion.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)