Activity for the week of 15 March-21 March 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
| Hokkaido (Japan)
| 43.384°N, 144.013°E
| Elevation 1499 m
A very small eruption occurred at Me-Akan (also called Meakan-dake, which means Meakan Peak) of the Akan volcanic complex on 21 March. Tremor began around 0628, the eruption apparently began around 0637, and an alert was issued by JMA at 0643. The eruption occurred from the volcano's NE flank. Ash was deposited on snow as far as 10 km SE of the volcano. The volcano is in a remote area and no populated areas were threatened. Me-Akan last erupted in 1998.
Sources: Gunma University, Reuters
| Mariana Islands (USA)
| 16.35°N, 145.67°E
| Elevation 790 m
During January and February, thin gas plumes from Anatahan were occasionally visible on satellite imagery, but became continuous and slightly more dense during 26 February to 19 March. On 17 March around 2200, seismicity abruptly increased by a factor of nearly two and continued at that level for 2 hours. On the 18th around 1400, seismicity again abruptly increased by a factor of nearly two and continued at that level for about 8 hours before returning to the baseline level prior to 17 March. The increased seismicity consisted of small (M 0-1) long-period earthquakes occurring approximately every minute or so, sometimes reaching two per minute. A total of about 600 such events were detected during 17 and 18 March. Volcanic Ash Advisories were issued by the Washington VAAC, but were cancelled when the plume was determined to contain gas and only insignificant amounts of ash. The Alert Level was raised from Normal; Aviation Color Code Green, to Advisory; Aviation Color Code Yellow around 20 March.
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)
| Luzon (Philippines)
| 12.769°N, 124.056°E
| Elevation 1535 m
On 21 March at 2258, a modest ash explosion occurred at Bulusan's summit crater. The phreatic explosion produced an ash cloud that rose ~1.5 km above the volcano (or 10,050 ft a.s.l.). Based on interpretations of seismic data, the event lasted ~20 minutes. It was accompanied by lightning and rumbling sounds. Ash drifted N, W, and SW of the volcano, and ~1 hour after the explosion light ash fell (producing ~5-mm-thick deposits) in Barangays (neighborhoods) Cogon, Tinampo, Gulang-Gulang, and Bolos in the town of Irosin. Ash also fell in Barangays Puting Sapa and Bura-Buran of Juban town, and other neighboring barangays under the municipalities of Irosin and Juban, Sorsogon. Three explosion-type earthquakes were also recorded on the 21st, at 2330, 2332, and 2337, but the accompanying eruptive events were not observed because the summit was obscured.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
| Central Java (Indonesia)
| 7.54°S, 110.446°E
| Elevation 2910 m
Increased seismicity at Merapi led CVGHM to raise the Alert Level from 1 to 2 (on a scale of 1-4) around 20 March. According to a news articles, small earthquakes were recorded at the volcano on 19 March and more than 200 were recorded during the week. Around 10,000 residents near the volcano were warned to prepare for possible evacuations if activity escalates.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Agence France-Presse (AFP)
| North Kermadec Ridge (New Zealand)
| 29.27°S, 177.92°W
| Elevation 516 m
An eruption began in the Green Lake area of Raoul Island volcano on 17 March around 0821. Based on interpretations of seismic data, the eruption appeared to have lasted for 30 minutes, with the most intense activity lasting 5-10 minutes. The eruption consisted of the ejection of mud and rocks, and a steam plume. A strong sequence of earthquakes began during the evening of the 12th that declined in number and size a few days before the 17th. According to GNS, the eruption appeared to have occurred with no immediate warning. New Zealand Department of Conservation officials evacuated a dozen staff on the island. News articles reported that one person remained missing on the island as of 22 March. The last eruption from the Green Lake area occurred during November 1964-April 1965.
Sources: GeoNet, Wellington Volcanic Ash Advisory Center (VAAC), Associated Press
| United States
| 59.363°N, 153.43°W
| Elevation 1252 m
Low-level eruptive activity continued at Augustine during 10-17 March. The seismicity changed from periods of prolonged volcanic tremor and closely spaced discreet earthquakes to episodic short-duration events. This change indicated that steady effusion of lava and dome growth gave way to activity characterized by slower effusion of lava and intermittent block-and-ash-flows, rock avalanches, and rockfalls originating from the summit lava dome. Observers saw numerous hot avalanches and prolonged periods of incandescence in the summit area and on the upper NE flank on several evenings. Satellite images showed that thermal anomalies persisted. Observations made during overflights of the volcano indicated that two lava flows on the N and NE flanks continued to advance slowly. Occasional collapses of the lava-flow fronts shed hot blocks and produced minor ash emissions. Photographs indicated that the new lava dome was about 70 m higher than the level of the lava dome formed in 1986. Augustine remained at Concern Color Code Orange.
Sources: US Geological Survey Alaska Volcano Observatory (AVO), Anchorage Volcanic Ash Advisory Center (VAAC)
| Andaman Islands (India)
| 12.278°N, 93.858°E
| Elevation 354 m
According to a news article, a team of scientists that visited Barren Island around 12 March found that the volcano was still very active and the height of the volcanic cone had increased by 50 m since eruptive activity began in May 2005. In addition, lava flows covered the NW side of the island.
Source: Indo-Asian News Service
| 1.22°N, 77.37°W
| Elevation 4276 m
During 13-20 March, seismicity at Galeras decreased in comparison to previous weeks and deformation was measured at the volcano. Plumes of mainly steam, gas, and small amounts of ash were emitted from the volcano and rose to a maximum height of 1.2 km above the volcano (or 18,000 ft a.s.l.). Galeras remained at Alert Level 3 ("changes in the behavior of volcanic activity have been noted").
Source: Servicio Geológico Colombiano (SGC)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 15-22 March, lava flowed off of a lava delta into the ocean at the East Lae`apuki entry and surface lava flows were occasionally visible. Background volcanic tremor was at normal levels at Kilauea's summit, with shallow earthquakes continuing to occur beneath the summit area and the upper E rift zone. Volcanic tremor reached moderate levels at Pu`u `O`o. Slight inflation and deflation occurred at the volcano.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| 16.72°N, 62.18°W
| Elevation 915 m
Cloudy conditions during 10-17 March limited visual observations of Soufrière Hills, however, lava-dome growth continued to be focused towards the E, NE, and NW as was evidenced by the production of large numbers of rockfalls and small pyroclastic flows. The ground deformation network showed a continuing trend of line shortening across the volcano. The sulfur-dioxide flux averaged 480 metric tons per day. The hydrogen chloride to sulphur dioxide ratio ranged between 1.1. and 2.1.
Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)
| United States
| 46.2°N, 122.18°W
| Elevation 2549 m
Growth of the new lava dome inside the crater of Mount St. Helens continued during 15-21 March, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. Monitoring instruments showed no significant change in patterns of earthquake activity or deformation. Very small periodic earthquakes occurred every few minutes that were punctuated by occasional larger (less than M 3) events. The active lava dome continued to build towards the W at about 1 m per day, consistent with the trend established over the previous few weeks. St Helens remained at Volcano Advisory (Alert Level 2); aviation color code Orange.
Source: US Geological Survey Cascades Volcano Observatory (CVO)
| 1.467°S, 78.442°W
| Elevation 5023 m
During 16-20 March, small-to-moderate explosions occurred at Tungurahua that consisted of gas, steam, and small amounts of ash. Plumes rose to a height of ~3 km above the volcano (or 26,300 ft a.s.l.).
Source: Instituto Geofísico-Escuela Politécnica Nacional (IG)
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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Google Earth Placemarks
A Google Earth network link for the Weekly Volcanic Activity Report was first made available on 1 April 2009. This file can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano page for that volcano and to the complete Weekly Report for that week.