Activity for the week of 24 May-30 May 2006
The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.
New Activity / Unrest
| 15.389°S, 167.835°E
| Elevation 1496 m
According to news reports, on 28 May aerial observations by scientists from the Department of Geology and Mines revealed that Lake Voui of Aoba volcano had changed from blue to red in color. Aoba remains at an Alert level 2, which means the crater area is restricted.
Sources: Commision of Volcanic Lakes (CVL), The Age News
| Grand Comore Island
| 11.75°S, 43.38°E
| Elevation 2361 m
According to the Toulouse VAAC, the Meteorology Office and Observatory of Comores reported an eruption of Karthala of gas and steam on 28 May at about 2105. During 28-29 May from 2300 to 0930, a thin sulfur-dioxide plume extending 60 km NW was visible on satellite imagery. On 29 May, at about 0830, volcanologists flew above the crater and confirmed that only steam and sulfur dioxide had been emitted. According to a news article, a lava lake fed by a central fountain was also observed.
Sources: Toulouse Volcanic Ash Advisory Centre (VAAC), Reuters
| Mariana Islands (USA)
| 16.35°N, 145.67°E
| Elevation 790 m
Based on a pilot report, the Washington VAAC reported that an ash plume from Anatahan reached an altitude of 3 km (10,000 ft) a.s.l. on 29 May and drifted W. Emissions from the E crater of vog (volcanic fog), steam, and a gas plume were visible on satellite imagery at about 1333 and increased prior to generation of the ash plume. A report issued from the Washington VAAC on 30 May at 0535 indicated a faint, low-level gas-and-ash plume extending from the summit.
Sources: Emergency Management Office of the Commonwealth of the Mariana Islands and United States Geological Survey Volcano Hazards Program, Washington Volcanic Ash Advisory Center (VAAC)
| Andaman Islands (India)
| 12.278°N, 93.858°E
| Elevation 354 m
Based on a pilot report, the Darwin VAAC reported an ash plume from Barren Island on 26 May that reached an altitude below 3 km (10,000 ft) a.s.l. and drifted N at 1230.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| Luzon (Philippines)
| 12.769°N, 124.056°E
| Elevation 1535 m
A phreatic ash explosion was recorded by the seismograph network at Bulusan between 2117 and 2130 on 25 May. Light ashfall ranging from trace amounts to deposits 2 mm thick was reported from the W and SW villages of Bacolod, Sankayon, Puting Sapa, Rangas, Mapili, Caladgao, and Buraburan in the municipality of Juban and Bolos in the municipality of Irosin.
PHIVOLCS reported that the ash explosion was more-or-less typical of activity at Bulusan during its current period of unrest and they expect more explosions to occur. Bulusan was at Alert Level 1, with a Permanent Danger Zone of 4 kilometers around the summit.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
| Chuginadak Island (USA)
| 52.825°N, 169.944°W
| Elevation 1730 m
The ash plume from Cleveland observed from the International Space Station on 23 May, drifted SW and had mostly dissipated by 24 May. No further activity was recorded. On 26 May AVO downgraded the Concern Color Code from Yellow to "Not Assigned".
Sources: US Geological Survey Alaska Volcano Observatory (AVO), Washington Volcanic Ash Advisory Center (VAAC)
| 14.473°N, 90.88°W
| Elevation 3763 m
On 29 May, INSIVUMEH reported that fumarolic emissions from Fuego reached a height of ~125 m above the volcano (~12,750 ft a.s.l.). Lava flows extended ~400 m SW toward the Ceniza River. Avalanches occurred from the lava-flow fronts. Incandescent material was propelled from the crater tens of meters. Plumes reached heights of 200 m above the crater (13,000 ft a.s.l.) and dispersed W and NW.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
Based on interpretations of seismic and satellite data, KVERT reported that ash explosions from the summit crater of Karymsky continued during 20-26 May. On 27 May, the Tokyo VAAC reported an ash plume an elevation of 3.7 km (12,000 ft) a.s.l. KVERT warned that activity from the volcano could affect nearby low-flying aircraft.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 24-30 May, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae`apuki entry. Incandescence was visible from East Pond Vent, January Vent, and Drainhole during 24-30 May, and from South Wall Complex on 24 and 30 May. Tremor remained at a very typical moderate level at Pu`u `O`o. Small amounts of inflation and deflation occurred during the report period.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| Papua New Guinea
| 4.08°S, 145.037°E
| Elevation 1807 m
According to the Darwin VAAC, an ash plume from Manam was visible on satellite imagery on 24 and 25 May, extending ~100 km WNW. On 26 May, an ash plume visible on satellite imagery reached an altitude below 3 km (10,000 ft) a.s.l. and drifted 48 km WNW. According to RVO (Rabaul Volcano Observatory), low-level activity occurred on 30 May.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| Central Java (Indonesia)
| 7.54°S, 110.446°E
| Elevation 2910 m
The Alert Level at Merapi remained at 4, the highest level, during 24-30 May. On 24-25 May, lava flows were observed moving SW towards the Krasak River and SE towards the Gendol River. According to news reports, on 27 May an M 6.3 earthquake that killed about 5,400 resulted in a three-fold increase in activity at Merapi. According to CVGHM, an M 5.9 earthquake coincided with pyroclastic flows of unknown origin that extended 3.8 km SW toward the Krasak River. During 28-30 May, multiple pyroclastic flows reached a maximum of 3 km SE toward the Gendol River and 4 km SW toward the Krasak and Boyong Rivers. Gas plumes reached a height above the volcano of 500 m (11,300 ft a.s.l.) on 25 May, 1,200 m (13,600 ft a.s.l.) on 26 May, 100 m (10,000 ft a.s.l.) on 29 May, and 900 m (12,600 ft a.s.l.) on 30 May.
Residents remained evacuated from villages within a 7 km radius from the volcano's summit and within 300 m of the banks of Krasak/Bebeng, Bedog, and Boyong Rivers to the SW, and Gendol River to the SE.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), The Canadian Press
| 16.72°N, 62.18°W
| Elevation 915 m
During 24-30 May, lava-dome growth continued at Soufrière Hills. On 23 May, the new lava dome was observed for the first time since the 20 May dome collapse. The new lava dome was darker than the previous lava dome and on 25 May, reached a height of 767 m. Rockfalls were observed on the NE and SW sectors of the new lava dome. The largest of several active vents were on the W side of the dome and were responsible for ash-venting episodes.
According to the Washington VAAC, ash-plume emissions continued during 24-30 May. On 24 May, emission of small volumes of gas and thin ash plumes continued and drifted W and SW. A pilot near St. Croix (NW) reported that the ash/haze layer reached an altitude of 1.5 km (5,000 ft) a.s.l. Ashfall was reported at San Juan (NW) airport. During 25-30 May, ash plumes reached an altitude of 4.6 km (15,000 ft) a.s.l. and drifted W and NW. On 24-26 May, a hot spot was visible on infrared satellite imagery.
Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)
| United States
| 46.2°N, 122.18°W
| Elevation 2549 m
During 24-25 May, seismicity remained at levels typical of the continuing lava-dome extrusion at Mount St. Helens. On 29 May, a M 3.1 earthquake and simultaneous large rockfall occurred. An ash plume was produced at 0810 that reached an altitude of 4.9 km - 6.1 km (16,000-20,000 ft) a.s.l. according to ground observations and pilot reports. An additional pilot report suggested the plume reached an altitude of 7.3 km (24,000 ft) a.s.l. By 1308, ash from the event was no longer visible on satellite imagery. On 30 May, the rockfall was confirmed to predominantly originate from the N side of the growing fin. The volcano remained at Volcano Advisory (Alert Level 2); aviation color code Orange.
Sources: US Geological Survey Cascades Volcano Observatory (CVO), Washington Volcanic Ash Advisory Center (VAAC)
| 1.467°S, 78.442°W
| Elevation 5023 m
During 24-30 May, visual observations of Tungurahua were limited due to heavy cloud cover. On 23 May, an ash plume reported by a pilot reached an altitude of 6.4 km (21,000 ft) a.s.l. A faint plume was visible on satellite imagery that drifted WSW. Slight ashfall was reported to the SW in Puela on 24 May, and the observatory reported a decrease in gas and ash emissions. On 25 May a significant meteorological advisory (SIGMET) indicated an ash plume to an altitude of 5 km (16,500 ft) a.s.l. On 27 and 30 May, the VAAC reported that the Instituto Geofísico observed ash plumes at altitudes of 7.9 km (26,000 ft) a.s.l. and 5 km (16,500 ft) a.s.l., respectively.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC), Reuters
| 16.355°S, 70.903°W
| Elevation 5672 m
According to a pilot report, the Buenos Aires VAAC reported that an ash plume from Ubinas on 24 May reached an altitude of 6.7 km (22,000 ft) a.s.l. and drifted E. On 25 May, an ash plume reached an altitude of 7 km (23,000 ft) a.s.l. and drifted NW. On 30 May, an ash plume visible on satellite imagery reached an altitude of 7.9 km (26,000 ft) a.s.l. and drifted E.
Buenos Aires Volcanic Ash Advisory Center
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC)
| New Britain (Papua New Guinea)
| 5.05°S, 151.33°E
| Elevation 2334 m
On 25 May, the Darwin VAAC reported a thin steam-and-ash plume from Ulawun that extended 30 miles WNW.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
Criteria & Disclaimers
The Weekly Volcanic Activity Report does not necessarily include all volcanic activity that occurred on Earth during the week. More than a dozen volcanoes globally have displayed more-or-less continuous eruptive activity for decades or longer, and such routine activity is typically not reported here. Moreover, Earth's sea-floor volcanism is seldom reported even though in theory it represents the single most prolific source of erupted material. The Weekly Volcanic Activity Report summarizes volcanic activity that meets one or more of the following criteria:
- A volcano observatory raises or lowers the alert level at the volcano.
- A volcanic ash advisory has been released by a volcanic ash advisory center (VAAC) stating that an ash cloud has been produced from the volcano.
- A verifiable news report of new activity or a change in activity at the volcano has been issued.
- Observers have reported a significant change in volcanic activity. Such activity can include, but is not restricted to, pyroclastic flows, lahars, lava flows, dome collapse, or increased unrest.
Volcanoes are included in the "New Activity/Unrest" section of the Weekly Volcanic Activity Report if the activity occurs after at least 3 months of quiescence. Once a volcano is included in the "New Activity/Unrest" section, updates will remain in that section unless the activity continues for more than 1 month without escalating, after which time updates will be listed in the "Continuing Activity" section. Volcanoes are also included in the "New Activity/Unrest" section if the volcano is undergoing a period of relatively high unrest, or increasing unrest. This is commonly equal to Alert Level Orange on a scale of Green, Yellow, Orange, Red, where Red is the highest alert. Or alert level 3 on a scale of 1-4 or 1-5.
It is important to note that volcanic activity meeting one or more of these criteria may occur during the week, but may not be included in the Weekly Volcanic Activity Report because we did not receive a report.
1. The Weekly Volcanic Activity Report is intended to provide timely information about global volcanism on a weekly basis. Consequently, the report is generated rapidly by summarizing volcanic reports from various sources, with little time for fact checking. The accuracy of the Weekly Volcanic Activity Report is dependent upon the quality of the volcanic activity reports we receive. Reports published in the Bulletin of the Global Volcanism Network are monthly, and more carefully reviewed, although all of the volcanoes discussed in the Weekly Volcanic Activity Report are not necessarily reported in the Bulletin. Because of our emphasis on rapid reporting on the web we have avoided diacritical marks. Reports are updated on the Weekly Volcanic Activity Report web page as they are received, therefore information may be included regarding events that occurred before the current report period.
2. Rapidly developing events lead to coverage that is often fragmentary. Volcanoes, their eruptions, and their plumes and associated atmospheric effects are complex phenomena that may require months to years of data analysis in order to create a comprehensive summary and interpretation of events.
3. Preliminary accounts sometimes contain exaggerations and "false alarms," and accordingly, this report may include some events ultimately found to be erroneous or misleading.
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