Activity for the week of 21 May-27 May 2008
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
| 42.833°S, 72.646°W
| Elevation 1122 m
Based on observations of satellite imagery and pilot reports, the Buenos Aires VAAC reported that during 21 and 23-27 May ash plumes from Chaitén rose to altitudes of 3-6.4 km (10,000-21,000 ft) a.s.l. and drifted N, NE, E, and SE. Cloudy conditions occasionally inhibited observations. A thermal anomaly was present on 26 May.
During aerial observations on 21 May, SERNAGEOMIN scientists observed a new lava dome that formed in the interior of an active crater on the N flank of the older lava dome. Explosions from the new lava dome generated reddish plumes and small pyroclastic flows that descended the N flank. Steam plumes were emitted from the western part of the dome. Eruption plumes generated from an area in the S part of the active crater drifted SE. The Alert level remained at Red. An overflight conducted on 24 May revealed that the lava dome had grown slightly and was just above the top of the old dome. A crater about 200 m in diameter S of the new dome emitted ash and gas. Block-and-ash flows traveled mostly N. Many of the areas rivers were gray with ash and pumice. Lahars along the Chaitén river continued to affect Chaitén town. During 24-25 May, ash plumes rose to an approximate altitude of 4.6 km (15,100 ft) a.s.l.; explosions occasionally propelled the gas-and-ash column to an altitude of 6.1 km (20,000 ft) a.s.l.
SERNAGEOMIN reported that during 23-26 May, the number and intensity of seismic events decreased, and explosions were less powerful and produced smaller volumes of material. On 25 May, ONEMI reported that the 50-km high-risk zone was reduced to 24 km due to the decrease in activity. Residents were permitted to retrieve property and animals from within the high-risk zone.
Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI), Buenos Aires Volcanic Ash Advisory Center (VAAC)
| Eastern Java (Indonesia)
| 8.108°S, 112.922°E
| Elevation 3657 m
CVGHM reported that during 15, 17-19, and 21 May, ash plumes rose from Semeru's summit, rockfalls descended the flanks, and multiple pyroclastic flows traveled 500-3000 m from the active crater. On 21 May, incandescent material was propelled from the summit. Based on visual observations and increased seismicity, CVGHM raised the Alert Level from 2 to 3 (on a scale of 1-4). The community was advised not to go within 4 km from the summit on the SE flank.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
| Kyushu (Japan)
| 31.593°N, 130.657°E
| Elevation 1117 m
Based on information from JMA, the Tokyo VAAC reported that on 22 May an eruption plume from Sakura-jima rose to altitudes of 2.4 km (8,000 ft) a.s.l. and drifted NE. An explosion was reported on 24 May.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)
| Bougainville (Papua New Guinea)
| 6.137°S, 155.196°E
| Elevation 1855 m
Based on observations of satellite imagery, the Darwin VAAC reported that on 22 May a low-level ash plume from Bagana rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted S.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| 14.473°N, 90.88°W
| Elevation 3763 m
INSIVUMEH reported that explosions from Fuego produced ash plumes to altitudes of 4.1-4.5 km (13,500-14,800 ft) a.s.l. during 22-27 May. The plumes drifted 5 km SW and ashfall was reported in areas downwind. The explosions produced rumbling and degassing sounds, and shock waves that rattled windows and structures 10-15 km away. During 26-27 May, constant avalanches of blocks descended W into the Taniluyá and Santa Teresa ravines.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
KVERT reported that seismic activity at Karymsky was slightly above background levels on 15, 16, and 21 May and at background levels the other days during 16-23 May. Gas-and-ash explosions that produced plumes to an altitude of 3.4 km (11,200 ft) a.s.l. may have occurred during 15-16 and 21-22 May. Observations of satellite imagery revealed that on 16 and 20 May a thermal anomaly was present in the crater. The Level of Concern Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
Based on observations during helicopter overflights, visual observations from HVO and National Park Service (NPS) crews, and web camera views, HVO reported that during 21-27 May lava flowed SE through a lava tube system underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex to the Waikupanaha ocean entry. Incandescence was occasionally noted from the TEB vent area. An overflight of Pu'u 'O'o crater on 23 May revealed that a new gas vent about 30 m below the E rim jetted gas at temperatures as high as 600 degrees Celsius.
During the reporting period, Kilauea summit earthquakes were located beneath the Halema'uma'u crater, S of the summit, along the S-flank and Koa'e faults, SW of Hi'iaka Crater, and along the SW rift zone. The eruption from the vent in Halema'uma'u Crater continued to produce white plumes with minor ash content that drifted mainly SW. During most nights incandescence was seen at the base of the plume. Seismic tremor was elevated. The sulfur dioxide emission rate was high and fluctuated between 990 and 1,540 tonnes per day when measured during 23-25 May. The background rate was 150-200 tonnes per day.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| New Britain (Papua New Guinea)
| 4.271°S, 152.203°E
| Elevation 688 m
RVO reported that during 21-28 May ash plumes from Rabaul caldera's Tavurvur cone rose to an altitude of 1.2 km (3,900 ft) a.s.l. and drifted N. Intermittent roaring noises were heard and ashfall was reported in Rabaul Town (3-5 km NW). During 25-27 May, ash and steam plumes drifted N, NW, and W, resulting in almost continuous ashfall in nearby areas. Occasional roaring noises were again reported.
Source: Rabaul Volcano Observatory (RVO)
| 14.757°N, 91.552°W
| Elevation 3745 m
INSIVUMEH reported explosions from Santa María's Santiaguito lava dome complex during 22-27 May. Resultant ash plumes seen during breaks in cloud cover rose to altitudes of 4.1-4.4 km (13,500-14,400 ft) a.s.l. and drifted S and SW. Ashfall was reported in areas nearby. Avalanches of blocks on the SW flanks were seen and heard. A lahar descended the Nima I river to the S on 25 May.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
| Central Kamchatka (Russia)
| 56.653°N, 161.36°E
| Elevation 3283 m
KVERT reported that seismic activity at Shiveluch was at background levels during 15-17 and 21 May and above background levels the other days during 16-23 May; gas-and-ash explosions may have occurred on 18, 19, and 20 May. According to video footage and visual observations, small hot avalanches descended the lava dome every day and fumarolic activity was noted. A large hot avalanche caused an ash plume to rise to an altitude of 4 km (13,100 ft) a.s.l. on 20 May. The plume drifted E. Observations of satellite imagery revealed that a thermal anomaly was present in the crater daily and an ash-and-steam plume drifted more than 100 km SE on 20 May.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| 16.72°N, 62.18°W
| Elevation 915 m
MVO reported that activity at Soufrière Hills decreased slightly during 17-23 May. On 23 May, several pulses of ash venting from Gages vent to the W produced ash plumes to an altitude of approximately 1.8 km (5,900 ft) a.s.l. and drifted E.
Based on pilot reports, information from MVO, and observations of satellite imagery, the Washington VAAC reported that during 23-27 May steam plumes with small amounts of ash or possible ash rose to altitudes of 1.2-1.4 km (4,000-4,500 ft) a.s.l. and drifted W and NW.
Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)
| 1.467°S, 78.442°W
| Elevation 5023 m
The IG reported that although visual observations were occasionally limited due to cloud cover during 21-27 May, ash and ash-and-steam plumes, often generated by explosions from Tungurahua, were spotted and rose to altitudes of 5.8-9 km (19,000-29,500 ft) a.s.l. Ash plumes drifted SW, W, and NW and ashfall was reported daily in areas within 8 km downwind. Roaring noises, "cannon shot" noises, and sounds resembling blocks rolling down the flanks were reported. On 22, 25, 26, and 27 May, windows vibrated in nearby areas, including at the Tungurahua Observatory (OVT) in Guadalupe, 11 km N. On 23 May, incandescence at the summit was seen at night. On 27 May, lahars descended a drainage in the Pampas sector to the S.
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
| 16.355°S, 70.903°W
| Elevation 5672 m
Based on SIGMET reports, the Buenos Aires VAAC reported that during 22-24 May ash plumes from Ubinas rose to altitudes of 4.9-7.9 km (16,000 and 26,000 ft) a.s.l. and drifted S, E, NE, and SE. On 26 May, a pilot reported that a plume rose to an altitude of km (18,000 ft) a.s.l. and drifted SSE. The plume was also identified on satellite imagery.
Source: Buenos Aires Volcanic Ash Advisory Center (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.
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