Roundup of Global Volcanic Activity – New Activity for the week of 21 June – 27 June 2017
Bogoslof | Fox Islands (USA) : AVO reported that slightly elevated surface temperatures at Bogoslof were identified in satellite images on 23 June, and steam emissions were occasionally observed the previous week. Beginning at 1649 on 23 June a significant explosive event was detected in seismic and infrasound data that lasted about 10 minutes. It produced an ash plume that rose as high as 11 km (36,000 ft) a.s.l. and drifted 400-490 km E. The event prompted AVO to raise the Aviation colour Code (ACC) to Red and the Volcano Alert Level (VAL) to Warning. Four additional explosions were detected, during 1918-1924, 2013-2021, 2104-2112, and 2152-2155, though any resulting ash plumes were not detected above the cloud deck at 8.5-9.1 km (28,000-30,000 ft) a.s.l. On 25 June the ACC was lowered to Orange and the VAL was lowered to Watch. At 1645 on 26 June an eruption which lasted about 14 minutes produced an ash plume that rose 7.6 km (25,000 ft) a.s.l. Seismic and lighting data indicated that a significant explosion began at 0317 on 27 June, prompting AVO to raise the ACC to Red and the VAL to Warning. The event lasted 14 minutes, and produced an ash plume that rose 9.1 km (30,000 ft) a.s.l. and drifted NW. The ACC was lowered to Orange and the VAL was lowered to Watch later that day.
Karymsky | Eastern Kamchatka (Russia) : KVERT reported that a thermal anomaly over Karymsky was identified in satellite images during 16-17 June. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).
Pavlof | United States : AVO reported that no unusual activity was detected in seismic or infrasound data at Pavlof during 21-26 June. Weakly elevated surface temperatures were identified in satellite images during 21-22 June, and a few clear webcam views revealed minor steaming. The Aviation colour Code remained at Yellow and the Volcano Alert Level remained at Advisory.
Reventador | Ecuador : IG reported that during the previous months activity at Reventador was characterized by an average of 50 explosions per day and long-period earthquakes indicating fluid movement. Ash plumes from explosions rose as high as 2 km above the crater rim, and small pyroclastic flows descended the flanks in almost all directions. However, at 1701 on 22 June the pattern of activity changed. Seismic signals indicating emissions became continuous, and spasmodic tremor emerged which was composed of numerous small explosions. Concurrent to the change in seismicity, small-to-moderate pyroclastic flows descended 4 km down the NE flank, and plumes with low-to-moderate ash content rose 2.5 km and drifted W. Pyroclastic-flow deposits were also noted in the upper basin of El Reventador river, E of the cone. During 22-23 June incandescent blocks rolled 500 m down the flanks, steam-and-ash plumes rose 2 km, and several pyroclastic flows traveled 900 m NE. Cloud cover sometimes prevented visual observations during 24-27 June though sometimes gas-and-ash plumes were seen rising no higher than 500 m above the crater rim. Incandescent blocks continued to descend the flanks, traveling as far as 650 m. “Cannon shot” sounds were heard at night during 24-25 June. During 26-27 June several episodes of incandescence at the crater were noted, and a lava flow traveled 2 km down the NE flank.
Rincon de la Vieja | Costa Rica : OVSICORI-UNA reported that at 1456 on 23 June a phreatic eruption at Rincón de la Vieja ejected sediment onto the upper N flank and generated a plume that rose 1-2 km above the summit. The plume dispersed sediments to the W and NW, near the Von Seebach crater (about 3 km SW of the active crater).
Sheveluch | Central Kamchatka (Russia) : KVERT reported that a thermal anomaly was identified daily in satellite images over Sheveluch during 16-23 June. Explosions on 17 June generated ash plumes that rose as high as 7 km (23,000 ft) a.s.l. and drifted 300 km E. Strong explosions the next day produced ash plumes that rose as high as 10 km (32,800 ft) a.s.l. and drifted 1,500 km ESE. The Aviation colour Code remained at Orange (the second highest level on a four-colour scale).
Ulawun | New Britain (Papua New Guinea) : RVO reported that during 1 May-23 June white plume rose from Ulawun. Seismicity was low (and dominated by small low-frequency earthquakes) although RSAM values slowly increased and then spiked on 13 June. Ash emissions began on 11 June and then became dense during 21-23 June. Based on analyses of satellite imagery, the Darwin VAAC reported that during 24-26 June ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W.