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SI/USGS Weekly Volcanic Activity Report 17-23 February 2010 25 February 2010

Posted by admin in activity reports, Africa, Bagana, Caribbean, Ecuador, eruptions, Hawaii, Indonesia, Japan, Kamchatka, Karymsky, Kilauea, Kliuchevskoi, Ol Doinyo Lengai, Papua New Guinea, Reventador, Russia, Sangay, Shiveluch, Soufrière Hills, Suwanose-jima, Talang, Tanzania, Tungurahua, Ulawun, United States, Weekly Volcanic Activity Reports.
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Just some of the notable volcanic activity reported at the Global Volcanism Program for the last week:

  • Ol Doinyo Lengai – steam emissions and fresh lava flows observed at Tanzania’s unique carbonate volcano
  • Kliuchevskoi – continuing lava flows, phreatic and strombolian activity
  • Tungurahua – continuing explosions, ashfall and lahars

SI/USGS Weekly Volcanic Activity Report 17-23 February 2010

Click on the map for a larger version (1280 x 898 pixels).

The Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report for 17-23 February 2010 is now available on the Global Volcanism Program website. The following is a summary and not a substitute for the full report.

New activity/unrest: Ol Doinyo Lengai (Tanzania), Reventador (Ecuador), Soufrière Hills (Montserrat), Ulawun (Papua New Guinea).

Ongoing activity: Bagana (Papua New Guinea), Karymsky (Russia), Kilauea (Hawaii, USA), Kliuchevskoi (Russia), Sakura-jima (Japan), Sangay (Ecuador), Shiveluch (Russia), Suwanose-jima (Japan), Talang (Indonesia), Tungurahua (Ecuador).

Note: a.s.l. = ‘above sea level’.

NEW ACTIVITY/UNREST

Ol Doinyo Lengai (Tanzania). Periodic eruptions from a small fissure and steam emissions from an area of the crater rim next to a part that had collapsed were observed on 11 February, and three fresh black hornitos were noted on the W part of the crater floor, a cone-shaped grey hornito in the middle of the floor and a new black lava flow to the S were seen during 14-15 February.

Reventador (Ecuador). A thermal anomaly was detected on 14 February, and Washington VAAC reported an ash emission on 18 February; seismic signals also indicated an emission that day. Ash was not identified in satellite imagery.

Soufrière Hills (Montserrat). During 12-19 February lava dome activity was at a low level. Rockfalls occurred from the inner walls of the 300-m-wide collapse scar left on the N flank by 11 February dome collapse event and from the dome summit. Gas measurements on 17 February and seismicity were consistent with lava-dome growth, but growth was unconfirmed. Inspection of the deposits from the 11 February collapse event revealed that the NE coastline had extended into the sea an additional 650 m. Pyroclastic flows razed many buildings in both Harris (3 km N) and Streatham (2 km NNW), and destroyed trees in the Gun Hill area (2 km NNW). Pyroclastic-flow deposits were approximately 15 m thick in the Trants region of the coast (near the old Bramble airport, about 5 km NE). A deep crater, similar in diameter to the collapse scar, was seen in the summit of the lava dome. The Hazard Level remained at 4.

Ulawun (Papua New Guinea). During 12-20 February white vapour emissions occurred that were occasionally forceful. A plume seen on satellite imagery on 14 February drifted NNE.

ONGOING ACTIVITY

Bagana (Papua New Guinea). During 1-21 February white vapour emissions occurred. Ash plumes were seen on 5 February and night-time incandescence was seen on 2, 12, 13 and 19 February. Sulphur dioxide plumes drifted ENE during 11-20 February and NNW on 20 and 21 February.

Karymsky (Russia). Seismic activity was above background levels during 11-14 February, possibly indicating weak ash explosions. Analyses of satellite imagery revealed a thermal anomaly over the volcano during that time and also on 15 February. Seismic activity was at background levels during 15-19 February. The Aviation Colour Code level remained at Orange.

Kilauea (Hawaii, USA). An active lava surface about 200 m below a vent in the floor of Halema’uma’u crater was reported 17-23 February. The lava surface circulated and occasionally spattered, and both rose and drained through holes in the cavity floor. Bursting bubbles and low lava fountains were also noted. A plume from the vent drifted mainly SW dropping small amounts of ash downwind. Measurements on 18 February indicated that the sulphur dioxide emission rate at the summit remained elevated at 600 tonnes/day (2003-2007 average rate = 140 tonnes/day). Lava from beneath the Thanksgiving Eve Breakout (TEB) and rootless shield complex flowed over 3 km SE through a lava tube system before breaking out onto the surface. Thermal anomalies detected by satellite and visual observations revealed active lava flows on the W side of the TEB flow field, on the pali, and on the coastal plain. Incandescence was sometimes seen from a vent low on the S wall of Pu’u ‘O’o crater.

Kliuchevskoi (Russia). During 12-19 February seismic activity was above background levels and lava continued to flow down the NW flank. Strombolian activity periodically ejected material 200 m above the crater and phreatic explosions occurred from the front of the lava flow. Satellite imagery revealed a large daily thermal anomaly at the volcano and gas-and-steam plumes that drifted over 240 km NE. The Aviation Colour Code level remained at Orange.

Sakura-jima (Japan). Tokyo VAAC reported that during 17-23 February plumes rose to 1.5-4 km a.s.l. and drifted NE, E, SE and S.

Sangay (Ecuador). Washington VAAC reported that on 22 February an ash plume rose to 7.6 km a.s.l. Ash was not identified in satellite imagery.

Shiveluch (Russia). During 12-19 February seismic activity was above background levels, possibly indicating ash plumes rising to 5.1 km a.s.l. Fumarolic activity was occasionally observed. Analyses of satellite imagery revealed a large daily thermal anomaly from the lava dome and ash plumes that drifted over 70 km in northern directions on 11, 13 and 17 February. The Aviation Colour Code level remained at Orange. Tokyo VAAC reported that on 23 February an eruption produced a plume that rose to 3 km a.s.l. and drifted N.

Suwanose-jima (Japan). Tokyo VAAC reported explosions during 17-19 and 21-22 February. Plumes occasionally rose to 1.2-1.8 km a.s.l. and drifted E and SE.

Talang (Indonesia). The Alert Level was lowered from 3 to 2 (on a scale of 1-4) on 17 February because of an overall decline in seismicity since February 2009. Visitors and tourists were advised not approach the crater.

Tungurahua (Ecuador). Explosions were detected by the seismic network during 16-23 February. Ash plumes were seen when weather conditions allowed, rising to 6-8 km a.s.l. and drifting S, SW, W and ENE. Ashfall was noted almost daily in areas to the SW and S. Blocks rolled down the flanks on 18 February. Lahars descended NW and W drainages on 20 February and a SW drainage on 22 February. On 21 February small block avalanches on the N flank generated pyroclastic flows.

ACKNOWLEDGEMENTS AND DISCLAIMER

The foregoing is a summary of the Smithsonian Institution/United States Geological Survey Weekly Volcanic Activity Report covering 17-23 February 2010. 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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