Activity for the week of 6 September-12 September 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
Cleveland
| Chuginadak Island (USA)
| 52.825°N, 169.944°W
| Elevation 1730 m
On 7 September, AVO raised the level of Concern Color Code for Cleveland from unassigned to Yellow after a short-lived explosion on 24 August was verified by video footage. The resultant ash plume reached an altitude of about 3 km (~10,000 ft) a.s.l. and produced ash fall. An hour later, only minor steaming from the summit was noted. A weak thermal anomaly in the summit crater was present in subsequent satellite images.
Source: US Geological Survey Alaska Volcano Observatory (AVO)
Etna
| Sicily (Italy)
| 37.748°N, 14.999°E
| Elevation 3295 m
On 14 July, a fissure opened on the E flank of the SE Crater of Etna and produced a lava flow that traveled E to the Valle del Bove. Moderate Strombolian activity from the E flank of the SE Crater produced a small amount of ashfall on Catania (~25 km SSE of the volcano). The lava flow reached a maximum distance of 3 km within the Valle del Bove and ceased on 24 July. On 26 July, strong explosions were heard from the rim of the NE crater.
On 31 August, Strombolian activity from the summit of the SE Crater produced lapilli and bombs that fell mainly in the crater. The ejecta filled the crater and overflowed on the E side on 5 September, forming lava falls that accumulated in a steep-sided circular depression on the middle part of the E flank. On 7 September, the sluggish a'a' flow breached the E rim and spread out on the E flank of the SE Crater and towards the Valle del Bove rim. Explosive activity at the SE Crater summit produced lava blocks that fell to the base of the cone.
On 10 September, a rockfall from a wall that divided the SE Crater and the depression on the middle part of the E flank produced an ash plume that drifted W. Lava flows and Strombolian activity from the summit of the SE Crater continued on 11 September.
Source: Sezione di Catania - Osservatorio Etneo (INGV)
Karymsky
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
KVERT reported on 8 September that the Concern Color Code level at Karymsky was lowered from Orange to Yellow. Approximately 30-90 shallow earthquakes occurred daily. During 1-4 September, a thermal anomaly was detected in the crater.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Mayon
| Luzon (Philippines)
| 13.257°N, 123.685°E
| Elevation 2462 m
Seismic activity and lava extrusion from Mayon decreased during 6-12 September. Steam plumes from the summit crater drifted mainly W, N, and E. Ground-deformation measurements showed an overall deflation. On 11 September, the Alert Level was lowered from 4 to 3 (scale is 0-5, 0 referring to No Alert status).
Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), News Balita, Reuters
Soufriere Hills
| Montserrat
| 16.72°N, 62.18°W
| Elevation 915 m
During 6-12 September, lava-dome growth at Soufrière Hills was substantial and concentrated on the W part of the edifice. A vent that had opened above Gage's Wall on 31 August vigorously emitted plumes of hot gases. A second vent near the summit of the dome emitted ash-and-steam plumes.
Based on information from the MVO, pilot reports, and the Piarco MWO, the Washington VAAC reported that ash, gas, and steam emissions on 6 and 7 September produced diffuse plumes that drifted WNW. On 10, 11, and 12 September, ash-and-gas plumes reached altitudes of 3 km (10,000 ft) a.s.l. and drifted E and SW. A hotspot was detected on satellite imagery on 6, 7, and 10-12 September.
Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC)
Talang
| Indonesia
| 0.979°S, 100.681°E
| Elevation 2575 m
CVGHM raised the Alert Level at Talang to 3 (on a scale of 1-4) on 9 September due to an increase in tremor. On 10 September, a brownish plume rose 250 m above the summit (~10,000 ft a.s.l.).
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Washington Post
Tengger Caldera
| Eastern Java (Indonesia)
| 7.942°S, 112.95°E
| Elevation 2329 m
CVGHM reported that the Alert Level for Tengger Caldera was raised one level to 3 (on a scale of 1-4) on 9 September due to an increase in tremor.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
Turrialba
| Costa Rica
| 10.025°N, 83.767°W
| Elevation 3340 m
Fumarolic activity and gas discharge in and to the W of Turrialba's central crater continued throughout August. On 30 August, scientists visiting the area noted that localized vegetation in and around the summit area had been heavily impacted by gases. Areas not affected by increased fumarolic activity in June 2005 had been singed by noxious gases, including a tree belt on the NW outer flank. Below the tree belt, farmers reported an intensification of gas odors. The shapes of the gas-scarred areas reflected prevailing wind directions.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)
Ongoing Activity
Aira
| Kyushu (Japan)
| 31.593°N, 130.657°E
| Elevation 1117 m
Based on information from JMA, the Tokyo VAAC reported that an explosion at Sakura-jima produced an eruption cloud on 6 September.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)
Arenal
| Costa Rica
| 10.463°N, 84.703°W
| Elevation 1670 m
In August, activity originating from Arenal's Crater C consisted of gas emissions, sporadic Strombolian eruptions, lava flows traveling N, and occasional avalanches from lava-flow fronts. Volcanic activity was at relatively low levels, however, with few eruptions occurring and a small amount of pyroclastic material ejected. Eruptions produced ash plumes that rose ~500 m above the crater (~7,100 ft a.s.l.). Ash and acid rain fell on the NE and SE flanks. Small avalanches of volcanic material traveled down several ravines. Crater D showed only fumarolic activity.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)
Kilauea
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 6-12 September, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae'apuki and East Ka'ili'ili entries. Incandescence was intermittently visible from the East Pond and January vents, South Wall complex, and Drainhole vent in Pu'u 'O'o's crater. Summit inflation S of Halema'uma'u caldera continued. Tremor at Pu'u 'O'o remained at a typical moderate level.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Poas
| Costa Rica
| 10.2°N, 84.233°W
| Elevation 2708 m
OVSICORI-UNA reported that during August, Laguna Caliente, a summit lake of Poás, was gray in color and produced gas columns that reached the crater rim. The level of the lake had dropped 47 cm with respect to July measurements and had a temperature of 41 degrees Celsius. Fumarolic activity from a pyroclastic cone on the floor of the crater produced gas plumes that drifted W and SW. New points of gas discharge were noted from the crater floor, the SE and NE crater walls, the N terrace, and the NE edge of the crater.
Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)
St. Helens
| United States
| 46.2°N, 122.18°W
| Elevation 2549 m
During 6-12 September, the lava dome at Mount St. Helens continued to grow and produce small rockfalls. On 9 and 10 September, five shallow earthquakes greater than M 2 occurred in association with the growing dome.
Source: US Geological Survey Cascades Volcano Observatory (CVO)
Tungurahua
| Ecuador
| 1.467°S, 78.442°W
| Elevation 5023 m
During 6-12 September, seismicity at Tungurahua remained low and visual observations were limited due to inclement weather. On 7 September, lahars descended the NW gorges of Chontapamba and Mandur. On 8 and 9 September, steam-and-gas plumes with little to no ash content rose to ~100-500 m above the summit (~16,800-18,100 ft a.s.l.) and drifted NW.
Source: Instituto GeofÃsico-Escuela Politécnica Nacional (IG)
Ubinas
| Peru
| 16.355°S, 70.903°W
| Elevation 5672 m
Based on pilot reports, the Buenos Aires VAAC reported continuous emission of ash plumes from Ubinas during 5, 9, and 11 September. The plumes rose to altitudes of ~4.9-5.5 km (~16,000-18,000 ft) a.s.l. and drifted NE and E.
Source: Buenos Aires Volcanic Ash Advisory Center (VAAC)
Criteria & Disclaimers
Criteria
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.
Disclaimers
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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