The Institute of Earth Sciences at the Nordic Volcanological Center (NVC) reported that during 28 April-4 May the eruption from Eyjafjallajökull continued to emit lava and produce steam and ash plumes. Booming sounds in the vicinity of the volcano were often heard. Scientists continued to measure meltwater discharge that flowed down the Gígjökull glacier into the Gígjökull lake basin, then into the Markarfljót River. On 30 April steaming blocks were deposited in the basin, and on 2 May, steam rising from the delta in the lake basin suggested near-boiling water temperatures.

On 28 April the eruption plume was not detected over 4 km altitude (13,100 ft) a.s.l., the level of meteorological clouds. Steam plumes rose above the lava that advanced N down the Gígjöjkull Glacier. Ash plumes rose above the crater; ashfall was seen on the W flanks and in an area about 32 km W. The next day the eruption plume was not visible, but likely did not exceed an altitude of 3.6 km (11,800 ft) a.s.l. Ashfall was reported in areas 1.5 km SW and 12 km SSW.

Steam plumes on 30 April rose to altitude of 4.5-5.1 km (14,800-16,700 ft) a.s.l. Ash plumes rose to lower altitudes, drifted S, and deposited ash in areas 10 km away. Ash plumes rose slightly higher the next day, to an altitude of 5.4 km (17,700 ft) a.s.l. Ashfall was noted in areas 22 km SE. An active lava flow to the N continued to generate steam plumes from interaction with ice.

A report on 2 May stated that during the previous 2-3 days ash plumes had become darker and wider than in the preceding week, explosivity had increased, and tephra fall-out had increased. The location of the steam plume N of the crater indicated that the lava flow had advanced more than 3 km from the crater. Steam and ash plumes continued to rise from the crater. Ashfall was reported in an area 40 km SE. The scoria cone at the crater continued to build. Conditions on 3 May were similar. The largest eruption plume rose to an altitude of 5.5 km (18,000 ft) a.s.l. Ashfall was noted 65-70 km ESE, and ash plumes were seen over the village of Vík, 40 km SE. The eruption plume was seen in satellite imagery as far as 200 km from Eyjafjallajökull on both days.

On 4 May ash plumes rose above the crater and steam plumes rose from the N flank. Lava had traveled 4 km N from the crater, and lava was ejected a few hundred meters from the crater. Ashfall was reported in areas 65-80 km ESE, cutting visibility to less than a few kilometers. An eruption plume was seen in satellite imagery as far as 400 km ESE to SE. According to news articles, airports throughout Ireland were temporarily shut down on 4 May due to ash-plume hazards.

Sources: Institute of Earth Sciences, Associated Press

KVERT reported that during 23-30 April seismic activity from Karymsky was above background levels, suggesting that possible ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. Volcanologists working in the area on 20 and 21 April saw gas-and-steam plumes containing some ash rise to an altitude of 3 km (10,000 ft) a.s.l. At night, Strombolian activity was occasionally observed. Satellite imagery revealed a daily thermal anomaly over the volcano. The Aviation Color Code level remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

The IG reported that on 29 April an explosion from Reventador produced a steam plume with low ash content. Meteorological clouds mostly prevented observations during 30 April-4 May.

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

CVGHM reported that observers at a post located 12.5 km NE of Rinjani saw one whitish-colored plume that rose 100 m from the volcano during February. Dense whitish plumes (and possibly brown) rose 500-900 m in March on 26 occasions and as high as 1,500 m in April on 41 occasions. Plumes seen on 1 and 2 May were "chocolate" in color and rose a maximum height of 1,600 m. From February through April seismicity decreased, although the maximum amplitude of earthquakes increased. CVGHM also noted that ash eruptions and ejected incandescent material fell within Rinjani caldera, but some ash was blown out of the caldera. The Alert Level was raised to 2 (on a scale of 1-4) on 2 May.

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

On 30 April, INSIVUMEH reported that explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose to altitudes of 2.8-3.7 km (9,200-12,100 ft) a.s.l. and drifted N and NW. Ashfall was reported in towns downwind. Fumarolic plumes rose 300 m above Caliente dome. A lahar traveled S down the Nima I River, carrying blocks up to 90 cm in diameter. On 4 May an ash plume rose to a maximum altitude of 4 km (13,100 ft) a.s.l.

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

OVDAS-SERNAGEOMIN reported that during February incandescence from Villarrica was seen at night through web cameras. The report reiterated that incandescence was typical; the Alert level remained at Green, Level 1. Video and photographs taken during 24-25 April, and posted on the Projecto Observación Visual Volcán Villarrica (POVI) website, showed Strombolian activity in the crater. Bursts of lava ejected from an unseen source did not rise above the crater rim. Gas plumes rose from the crater.

Sources: Proyecto Observación Villarrica Internet (POVI), Servicio Nacional de Geología y Minería (SERNAGEOMIN)

Based on information from JMA, the Tokyo VAAC reported that during 28 April-5 May explosions from Sakura-jima often produced plumes. Those plumes, along with ash plumes occasionally seen by pilots, rose to altitudes of 1.2-3.4 km (4,000-11,000 ft) a.s.l. and sometimes drifted NE, E, and SE.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)

Based on analyses of satellite imagery, the Darwin VAAC reported that on 28 and 30 April and during 1-3 May ash plumes from Batu Tara rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted 35-95 km SW, W, and NW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

The Darwin VAAC reported that on 3 May an ash plume from Dukono was seen on satellite imagery drifting about 90 km W at an altitude of 3 km (10,000 ft) a.s.l.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Based on information from the Vanuatu Geohazards Observatory, the Wellington VAAC reported that on 29 April and 2 May ash plumes from Gaua were seen on satellite imagery drifting W and NW at an altitude of 3 km (10,000 ft) a.s.l.

Source: Wellington Volcanic Ash Advisory Center (VAAC)

During 28 April-4 May HVO reported that activity at Kīlauea continued at the summit and the east rift zone. At the summit, episodic rising and falling of the lava-pool surface continued at the deep pit inset within the floor of Halemaʻumaʻu crater; glow from the vent was visible. On most mornings the plume of gas and ash from the summit vent drifted NW, W, and SW. On 29 April small rockfalls disrupted the surface of the pond, producing "dusty" plumes. Sulfur dioxide emission rates measured at the summit during 28-29 April were in the 800-1,000 tonnes/day range.

At the east rift zone, lava flowed through tubes to supply a surface flow that had advanced down the Pūlama pali, onto the coastal plain, heading S, and reached the ocean on 29 April. Lava continued to flow into the ocean, just W of the "old" coastal viewing area during the rest of the reporting period. Lava also flowed along the E margin, between the highway and the coast. Incandescence was sometimes seen from a vent low on the S wall of Puʻu ʻŌʻō crater.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

KVERT reported that during 22-30 April seismic activity from Kliuchevskoi was above background levels. Strombolian activity was noted and lava continued to flow down the flanks. Gas-and-steam plumes containing small amounts of ash were seen on 22 April. Similar plumes rose to an altitude of 7.3 km (23,900 ft) a.s.l. during 25-27 April, and drifted W and SW. Satellite imagery revealed a large daily thermal anomaly from the volcano. An ash plume drifted about 65 km W on 24 April, and gas-and-steam plumes drifted 55 km W and SW during 24-27 April. Based on analyses of satellite imagery, the Tokyo VAAC reported that on 3 May a possible eruption produced a plume that rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted W. The Aviation Color Code level remained at Orange.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC), Kamchatkan Volcanic Eruption Response Team (KVERT)

KVERT reported that during 23-30 April seismic activity from Shiveluch was above background levels and suggested that possible ash plumes rose to an altitude of 5.7 km (18,700 ft) a.s.l. During 22-25 April ash plumes from hot avalanches rose to an altitude of 3 km (10,000 ft) a.s.l. and fumarolic activity from the lava dome was noted. Satellite imagery revealed a large daily thermal anomaly from the lava dome, and ash plumes that drifted about 60 km SE on 28 April. The Aviation Color Code level remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose-jima on 29 April, and during 1 and 4-5 May. Details of possible resulting plumes were not reported.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)