Based on analyses of satellite imagery, KVERT reported that during 22-29 April a large bright thermal anomaly was detected over Kizimen daily and ash plumes drifted 135 km in multiple directions. Ground-based observations indicated that gas-and-steam plumes with a small amount of ash rose to an altitude of 3.5 km (11,500 ft) a.s.l. and drifted W during 20-21 April.
SERNAGEOMIN reported that during 1-15 April a camera installed in Romeral, approximately 61 km NW of Planchón-Peteroa, recorded predominantly white vapor plumes that rose at most 600 m. During 16-19, 21 and 25-29 April episodes of ash-plume production changed from discreet plumes to more continuous emissions. Ash plumes during 17-19 and 29 April rose 1.2 km and contained ash- to lapilli-sized particles.
ODVAS-SERNAGEOMIN reported that on 26 April an overflight was conducted in response to recent increased seismicity and nearby residents noting fumarolic activity in the vicinity of Puyehue-Cordón Caulle. Scientists did not observe anything unusual that would indicate increased activity at Puyehue or Cordón Caulle, just typical fumarolic activity. On 27 April a seismic swarm was detected at depths of 4-6 km; a majority of the events were hybrid earthquakes and the largest was M 3.9.
On 2 May, GeoNet reported that the temperature of Ruapehu's summit Crater Lake continued to slowly cool and was about 30 degrees Celsius, down from a peak of 41 degrees in March. The lake level remained below the overflow level and no earthquakes had been located within 10 km of the Crater Lake for two weeks. The Aviation Colour Code was lowered to Green and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
IG reported that, although visual observations of Tungurahua were occasionally limited due to cloud cover during 26 April-3 May, ash plumes were noted daily and rose to altitudes of 7-12 km (23,000-39,400 ft) a.s.l. The plumes drifted in multiple directions. Ashfall was reported daily in areas within 8 km NNE, N, NW, W, and SW.
Based on information from JMA, the Tokyo VAAC reported that during 27-30 April and 2-3 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted N, NE, E, SE, and S. On 29 April and 2 May, pilots observed ash plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted S and SE.
Based on analyses of satellite imagery, the Darwin VAAC reported that during 28 April-3 May ash plumes from Batu Tara rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 10-130 km N, NW, W, and SW.
Based on analyses of satellite imagery, the Darwin VAAC reported that during 28 April-2 May ash plumes from Dukono rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted 55-150 km NW, W, and SW.
Wed, 27 Apr 2011, 06:00
INSIVUMEH reported that during 28-29 April explosions from Fuego produced ash plumes that rose 300-600 m above the crater and drifted SW and S. The explosions sometimes produced shock waves. Lava flows traveled 200 m S and block avalanches descended the Ceniza and Santa Teresa drainages.
Read allWed, 27 Apr 2011, 06:00
KVERT reported moderate seismic activity at Karymsky during 22-29 April and a thermal anomaly that was detected daily in satellite imagery. Seismic data indicated that possible ash plumes rose to an altitude of 3.4 km (11,200 ft) a.s.l. Visual observations showed that moderate explosive activity continued.
Read allWed, 27 Apr 2011, 06:00
During 27 April-3 May, HVO reported that the level of Kilauea's summit lava lake fluctuated but remained mostly stable deep in the vent inset within the E wall of Halema'uma'u Crater. A gas plume from the vent drifted SW and deposited very small amounts of ash nearby. At Pu'u 'O'o crater, lava from one or two vent sources continued to fill in a new lava lake in the center of the crater floor.
Read allWed, 27 Apr 2011, 06:00
INSIVUMEH reported that during 28-29 April explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose 600-800 m above the crater and drifted S, SW, and W. Block avalanches descended the flanks of Caliente dome. At night pyroclastic flows traveled down the Rio Nima I and Rio Nima II drainages.
Read allWed, 27 Apr 2011, 06:00
KVERT reported that during 22-29 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 6.7 km (22,000 ft) a.s.l. Satellite imagery showed a thermal anomaly daily on the lava dome. According to ground-based observations during 22 and 25-27 April ash plumes rose to an altitude of 7.5 km (24,600 ft) a.s.l. and drifted N and SE.
Read allWed, 27 Apr 2011, 06:00
Based on information from JMA, the Tokyo VAAC reported explosions from Suwanose-jima on 3 May. Details of a possible resulting plume were not reported.
Read allWed, 27 Apr 2011, 06:00
Based on analyses of satellite imagery, the Darwin VAAC reported that on 27 April an ash plume from Tengger Caldera's Bromo cone rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted about 75 km WSW. On 2 May an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted about 75 km N.
Read allWed, 20 Apr 2011, 06:00
In addition to producing ashfall 45 km to the NNW on 14 April, KVERT reported that the explosive eruption from Bezymianny also generated a viscous lava flow on the SE flank. Incandescence from the lava flow was visible on 19 April. Satellite imagery showed a thermal anomaly during 15-22 April, and small ash-and-gas plumes on 16 April.
Read allWed, 20 Apr 2011, 06:00
On 23 April, a Northern Mariana Islands status report noted that a NOAA research vessel in the vicinity of Pagan reported night time observations of incandescence at the summit of the volcano. Eruptive activity was considered currently to be at a low level; however with the possibility that the activity may escalate the Aviation Color Code for Pagan was raised to Yellow and the Volcano Alert Level to Advisory. Recent satellite image observations were obscured by clouds.
Read allWed, 20 Apr 2011, 06:00
On 18 April, GeoNet reported that the temperature of Ruapehu's summit Crater Lake was slowly cooling and decreased to 33-34 degrees Celsius from a peak of 41 degrees in March. A general decline of activity had been noted since 4 April, including lower carbon dioxide gas flux, less seismicity, modest change in the Crater Lake water chemistry, and cessation of lake overflow accompanying the start of the cooling trend. The Aviation Colour Code remained at Yellow and the Volcanic Alert Level remained at 1 (signs of volcano unrest).
Read allWed, 20 Apr 2011, 06:00
During 12-19 April, PHIVOLCS reported that between 6 and 19 daily volcanic earthquakes at Taal were detected by the seismic network. Some of the earthquakes were felt by nearby residents on the SE part of the island. The Alert Level remained at 2 (on a scale of 0-5).
Read allWed, 20 Apr 2011, 06:00
On 22 April, IG reported that in recent months the seismic network at Tungurahua detected volcano-tectonic earthquakes, indicating increased pressure in the volcano. Deformation of the NW quadrant that began in early February was slow but continuous, and then accelerated during the previous nine days. On 21 April gas-and-ash plumes caused fine ashfall in Choglontús and Cahuají (8 km SW), Pillate (8 km W), Cotaló (8 km NW), Juive (7 km NNW), and Baños (8 km N).
Read allWed, 20 Apr 2011, 06:00
Based on information from JMA, the Tokyo VAAC reported that during 21-25 April explosions from Sakura-jima produced plumes that rose to altitudes of 1.2-3 km (4,000-10,000 ft) a.s.l. and occasionally drifted N, NE, E, and SE. On 21 and 25 April, pilots observed ash plumes that rose to altitudes of 2.7-3.4 km (9,000-11,000 ft) a.s.l.
Read allWed, 20 Apr 2011, 06:00
Based on notices from the Manila airport (RPLL), the Tokyo VAAC reported that on 20, 22, and 26 April ash from Bulusan was observed. PHIVOLCS reported that only diffuse steam rose from the SE vents during 20-23 April. During cloud breaks on 26 April, diffuse steam plumes from the NW and SE vents were observed rising about 50 m and drifting WSW.
Read allWed, 20 Apr 2011, 06:00
Based on analyses of satellite imagery, the Darwin VAAC reported that during 21-22 April ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted less than 85 km NE and E.
Read allWed, 20 Apr 2011, 06:00
KVERT reported moderate seismic activity at Karymsky during 15-22 April. Seismic data indicated that possible ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. A thermal anomaly was detected in satellite imagery on 16, 18, and 21 April. The Aviation Color Code remained at Orange.
Read allWed, 20 Apr 2011, 06:00
During 20-26 April, HVO reported that activity at Kilauea continued from the summit caldera and from Pu'u 'O'o crater. The level of the circulating lava-pool surface in a deep pit below the Halema'uma'u crater floor periodically fluctuated. A gas plume from the vent drifted mostly SW, and deposited very small amounts of ash nearby.
Read allWed, 20 Apr 2011, 06:00
KVERT reported that during 15-22 April seismicity from Kizimen was high, with many shallow volcanic earthquakes and volcanic tremor continuing to be detected. Satellite images showed a large bright thermal anomaly daily on the volcano. Ash plumes drifted in multiple directions as far as 254 km during 14-18 and 21 April.
Read allWed, 20 Apr 2011, 06:00
Based on a SIGMET notice, the Buenos Aires VAAC reported that on 26 April an ash plume from Planchón-Peteroa rose to an altitude of 5.8 km (19,000 ft) a.s.l. and drifted E.
Read allWed, 20 Apr 2011, 06:00
KVERT reported that during 15-22 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 3.2 km (10,500 ft) a.s.l. Satellite imagery showed a thermal anomaly on the lava dome during 15-18 and 20 April, and ash plumes that drifted 55 km NE on 17 April. Based on information from KEMSD and information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 22 April an eruption produced plumes that rose to altitudes of 4.3-7.3 km (14,000-24,000 ft) a.s.l. and drifted W and NW.
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