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SI/USGS Weekly Volcanic Activity Report 16-22 December 2009 23 December 2009

Posted by admin in activity reports, Alaska, Bezymianny, Caribbean, Chaitén, Chile, Cleveland, Ecuador, eruptions, Gaua, Hawaii, Indonesia, Japan, Kamchatka, Karymsky, Kilauea, Kliuchevskoi, Mayon, Pacific, Russia, Sakura-jima, San Cristóbal, Shiveluch, Soufrière Hills, Suwanose-jima, United States, Vanuatu, Weekly Volcanic Activity Reports.
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SI/USGS Weekly Volcanic Activity Report 16-22 December 2009

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The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report for 16-22 December 2009 is available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

New activity/unrest: Bezymianny (Russia), Cleveland (Alaska, USA), Gaua (Vanuatu), Mayon (Philippines), San Cristóbal (Nicaragua).

Ongoing activity: Chaitén (Chile), Karymsky (Russia), Kilauea (Hawaii, USA), Kliuchevskoi (Russia), Sakura-jima (Japan), Sangay (Ecuador), Shiveluch (Russia), Soufrière Hills (Montserrat), Suwanose-jima (Japan).

Note: a.s.l. = ‘above sea level’.

NEW ACTIVITY/UNREST

Bezymianny (Russia). KVERT reported that seismic activity from Bezymianny increased on 8 December. After a significant thermal anomaly was detected in satellite imagery on 17 December, the Level of Concern Colour Code was raised to Red. A few hours later a large explosive eruption produced ash plumes that were seen drifting as far as 350 km W and NW in satellite imagery. Ash plumes likely rose to altitudes greater than 10 km a.s.l.; clouds in the area prevented visual observations. Ashfall up to 3 mm thick was noted in Kozyrevsk, 45 km W, and other surrounding villages. The Level of Concern Color Code was lowered to Orange after seismic activity significantly decreased. On 18 December another large thermal anomaly was seen over the volcano and on the SE flank. Gas-and-steam activity was also noted. During 19-20 December, a thermal anomaly continued to be detected in satellite imagery. KVERT lowered the Level of Concern Colour Code to Yellow on 21 December.

Cleveland (Alaska, USA). On 18 December AVO reported that a diffuse ash plume emitted from Cleveland on 12 December was retrospectively detected in satellite imagery. No other activity was noted.

Gaua (Vanuatu). On 14 December Vanuatu Geohazards Observatory reported that activity from Gaua during the previous month was characterized by continuous ash emissions accompanied by periodic steam emissions. Ashfall was reported in the W part of the island. Satellite imagery revealed that periods of significant gas emissions were more frequent than during November. Ash emissions during 14-18 December were thicker and darker, and possibly represented a new eruptive phase. Ash plumes continued to drift W and produce ashfall. The Vanuatu Volcanic Alert Level remained at 2 (on a scale of 0-4).

Mayon (Philippines). PHIVOLCS reported that during 14-19 December sulphur dioxide emissions from Mayon fluctuated between 750 and 2,034 tonnes/day. During 15-16 December detached fragments from lava accumulating in the summit crater traveled as far as 4 km down the SE-flank Bonga-Buyuan gully, and lava flows traveled 700-800 m. Occasionally detached lava fragments produced small pyroclastic surges down the SW flank that generated light ashfall 13 km S and W in Camalig and Guinobatan, respectively. Steam plumes rose 200 m above the crater rim and drifted SW and WSW. During 17-20 December the seismic network detected 66 explosion-type signals; only 23 events were seen during periods of good visibility. These explosions produced dark gray to dark brown ash plumes that rose 500-2,000 m above the crater rim and drifted SW. Harmonic tremor was detected by the seismic network. Brownish-coloured steam and intensified incandescence at night were noted. On 20 December lava flows had advanced 4.5 km from the crater. PHIVOLCS raised the Alert Level to 4 (on a scale of 0-5) and recommended that the Extended Danger Zone (EDZ) encompass an area 8 km S from the summit and 7 km N from the summit. During 20-22 December the rate and intensity of seismic signals dramatically increased. The sulphur dioxide emission rate also increased; 6,089-6,529 tonnes/day was measured. Booming and rumbling sounds, and intensified crater incandescence, were noted. Lava fountains rose 200 m above the crater and lava flowed as far as 5 km down the Bonga-Buyuan, Miisi, and Lidong gullies. According to news articles, more than 47,000 people from 30 villages were in evacuation centers across Albay province. About 3,000-6,000 residents had not evacuated.

San Cristóbal (Nicaragua). Based on METAR weather reports, the Washington VAAC reported that on 22 December a gas-and-steam plume that rose from San Cristóbal possibly contained ash.

ONGOING ACTIVITY

Chaitén (Chile). SERNAGEOMIN reported that during 1-15 December Chaitén’s lava-dome complex produced steam, gas, and ash plumes that rose 2 km above the lava domes. On 7 December emissions originated from the N and S areas of the complex. Block-and-ash flows were noted the next day. The Alert Level remained at Red. Based on web camera views and SIGMET notices, the Buenos Aires VAAC reported that on 18 December an ash plume drifted SSE at altitudes of 1.8-2.4 km a.s.l.

Karymsky (Russia). KVERT reported that during 11-13 and 17 December a thermal anomaly over Karymsky was detected in satellite imagery. Seismic activity was above background levels on 12 and 13 December; data were not available during 11-21 December due to technical problems. The Level of Concern Colour Code remained at Orange.

Kilauea (Hawaii, USA). During 16-22 December HVO reported that lava flowed SE from beneath Kilauea’s Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the ocean at Waikupanaha. Incandescence was seen almost daily coming from Pu’u ‘O’o crater. The vent in Halema’uma’u crater continued to produce an off-white plume that drifted E and SW, dropping small amounts of ash downwind. Incandescence originated from a few holes in the deep floor of the vent cavity. Occasionally, lava ponded on the floor of the cavity. Spatter originated from a small spatter cone on the E side of the vent cavity floor. Spatter from the opening frequently fed small lava flows that travelled down the flank of the cone. The sulphur dioxide emission rate at the summit remained elevated; 600 tonnes/day were measured on 18 December. The 2003-2007 average rate was 140 tonnes/day.

Kliuchevskoi (Russia). KVERT reported that during 11-21 December seismic activity from Kliuchevskoi was above background levels. Satellite imagery revealed a large daily thermal anomaly at the volcano. The Level of Concern Colour Code remained at Orange.

Sakura-jima (Japan). Based on information from JMA, the Tokyo VAAC reported that during 16-17 and 20-22 December explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-2.4 km a.s.l. and drifted E, SE, and S. On 19 and 22 December, pilots reported that ash plumes rose to altitudes of 2.1-2.4 km a.s.l.

Sangay (Ecuador). Based on pilot observations, the Washington VAAC reported that on 18 and 21 December ash plumes from Sangay rose to an altitude of 7.9 km a.s.l. and drifted W. Ash was not identified in satellite imagery, although weather clouds were present in the area. Thermal anomalies were occasionally detected in the satellite imagery.

Shiveluch (Russia). KVERT reported that during 11-21 December seismic activity from Shiveluch was above background levels, possibly indicating ash plumes rising to an altitude of 5.5 km a.s.l. Analyses of satellite imagery revealed a large daily thermal anomaly from the lava dome. The Level of Concern Colour Code remained at Orange.

Soufrière Hills (Montserrat). MVO reported that during 11-19 December activity from the Soufrière Hills lava dome continued at a high level. Night-time incandescence and observations with a high resolution thermal camera showed that activity was concentrated on the NW flank. Pyroclastic flows and semi-continuous rockfalls traveled down the NE, N, and NW flanks, channelling NE directly into Whites Ghaut and continuing into Whites Bottom Ghaut. Pyroclastic flows also traveled as far as 2 km NW down Tyers Ghaut multiple times a day, occasionally as far as 2 km W down Gages valley, and rarely E down Tar River valley. Fresh deposits from small pyroclastic flows moving S were seen at the head of the White River and Gingoes Ghaut. On 19 December heavy ashfall occurred in several areas in NW Montserrat. The Hazard Level remained at 4.

Suwanose-jima (Japan). Based on information from JMA, the Tokyo VAAC reported eruptions from Suwanose-jima during 17-20 and 22 December. A plume rose to an altitude of 1.5 km a.s.l. on 22 December.

ACKNOWLEDGEMENTS AND DISCLAIMER

The foregoing is a summary of the Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 16-22 December 2009. It is provided for information only, and is based on but not a substitute for the full report, which comes with its own criteria and disclaimers. The map base is derived from the Smithsonian Institution/USGS/US Naval Research Laboratory This Dynamic Planet website.

For all our coverage of the SI/USGS Weekly Volcanic Activity Reports: Weekly Volcanic Activity Reports « The Volcanism Blog.

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