Activity for the week of 7 December-13 December 2005
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
During 6-10 December, small-scale volcanic activity that began at Aoba (also locally called Mt. Manaro) on 27 November continued from active vents within Lake Vui, the summit crater lake. Molten material entered the crater lake and reacted with water, producing small explosive eruptions and a plume of steam and gas that rose to a height of 3.9-4.5 km (12,800-14,800 ft) a.s.l. The eruption built a cone around the active vents, enclosing them on three sides and forming an island ~200 m wide and 50-60 m high in the lake. There were two active vents; one emitted water, rocks, and mud, and the other emitted steam and gas. As of 10 December, the eruption had little effect outside of the crater lake (minor ashfall occurred only during the first 3 days after the eruption). During the report period, volcanic tremor was recorded at the volcano and a moderate sulfur-dioxide flux was measured (~2,000 tons per day). There was no evidence of ground uplift or cracking near the lake, suggesting that there was no large volume of magma close to the surface.
Sources: GeoNet, Vanuatu Meteorology and Geo-hazards Department (VMGD)
| 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 on 9 December produced a plume to a height of ~2.7 km (9,000 ft) a.s.l. that drifted S.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)
| United States
| 59.363°N, 153.43°W
| Elevation 1252 m
Seismicity remained at elevated levels at Augustine during 30 November to 12 December. On 12 December a steam plume visible on video and satellite images extended 75 km SE of the volcano. During 9-12 December, changes in the style of earthquake activity at the volcano were recorded and there were reports of gas emissions and steaming. Seismic events on 9 and 11 December may have perturbed the hydrothermal system, initiating steam explosions. These events were consistent with reports of steaming at the summit observed on 10 December, and a distinct sulfur smell ("like from a sewer") in the air on the evening of 11 December at Nanwalek and Port Graham, approximately 80 km E of the volcano. Augustine remained at Concern Color Code Yellow.
Source: US Geological Survey Alaska Volcano Observatory (AVO)
| Central Kamchatka (Russia)
| 55.972°N, 160.595°E
| Elevation 2882 m
After an explosive eruption at Bezymianny on 30 November, seismic activity at the volcano decreased to background levels. On 2 December the Concern Color Code was reduced from Orange to Yellow. On 9 December, KVERT reported that based on past experience with Bezymianny, a viscous lava flow was probably active at the summit lava dome and there were no indications that an explosive eruption was imminent.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| 1.22°N, 77.37°W
| Elevation 4276 m
Due to a decrease in volcanic activity at Galeras, on 28 November INGEOMINAS reduced the Alert Level at the volcano from 2 (probable eruption in days to weeks) to 3 (changes in the behavior of volcanic activity have been noted). Through 12 December, seismicity was recorded that was indicative of fluids moving within the volcano, small changes in deformation occurred, and emitted gas rose to a height of ~500 m above the volcano (or 15,700 ft a.s.l.).
Source: Servicio Geológico Colombiano (SGC)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
Seismicity at Karymsky remained above background levels during 1-2 December, and there were no seismic data during 3-9 December. Ash clouds were visible on satellite imagery extending SE on 6 and 7 December. Karymsky remained at Concern Color Code Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 9-12 December, lava from Kilauea continued to enter the sea at the East Lae`apuki area and surface lava flows were visible on the Pulama pali fault scarp. Background volcanic tremor was near normal levels at Kilauea's summit. Volcanic tremor reached moderate levels at Pu`u `O`o. Small amounts of deformation occurred at the volcano.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| 19.023°N, 98.622°W
| Elevation 5393 m
On 1 December at 0653, a moderate explosion at Popocatépetl produced an ash plume to a height of ~5 km above the volcano's summit (or 34,200 ft a.s.l.). An intense episode lasted ~2 minutes, and was followed by high-frequency tremor for 30 minutes. Ash drifted NE and fell in Amecameca, ~20 km NW of the volcano. An explosion on 1 December at 0920 produced an ash plume to ~2.5 km above the summit (or 26,000 ft a.s.l.) that also drifted NE. After this explosion, there was an increase in the number of small explosions, some of which involved small amounts of ash. After an explosion on 4 December, ash fell in the states of Tlaxcala (50 km NE of the volcano) and Puebla (60 km E of the volcano) and the volcanic activity returned to previous lower levels. As of 12 December, only emissions of steam and gas occurred.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
| El Salvador
| 13.853°N, 89.63°W
| Elevation 2381 m
Seismic activity began to increase at Santa Ana on 26 November. At that time, hundreds of metric tons of sulfur dioxide were emitted from the volcano each day, which was not as high as levels measured prior to the 1 October eruption. Gas emissions rose to ~300 m above the volcano and only slight changes were noted in the color of the lagoon in the interior of the crater. SNET stated that the high level of activity indicated that an eruption could occur in the following days. During 7-12 December, activity was still at high levels. The Alert Level remained at Red, the highest level, within a 5-km-radius around the volcano's central crater.
Source: Servicio Nacional de Estudios Territoriales (SNET)
| 14.757°N, 91.552°W
| Elevation 3745 m
On 24 November at 0955 an eruption at Santa María's Santiaguito lava-dome complex produced an ash cloud to a height of ~4 km above the volcano (or 25,500 ft a.s.l.). The eruption was accompanied by a pyroclastic flow that traveled to the S. Fine ash fell 6-7 km S of the volcano, impacting properties in the area. During 2-12 December, moderate-to-strong explosions produced ash plumes that rose to ~1.5 km above the volcano (or 17,300 ft a.s.l.). Pyroclastic flows occasionally accompanied explosions and traveled towards the SW. Several avalanches of volcanic material also occurred during the report period.
Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Washington Volcanic Ash Advisory Center (VAAC)
| 16.72°N, 62.18°W
| Elevation 915 m
Activity at Soufrière Hills remained at elevated levels during 2-9 December. Camera images of the lava dome indicated that extrusion rates were slightly lower than during previous report periods. The height of the lava dome only slightly increased. Most growth was focused towards the SE where the flank had been pushed out laterally. Incandescence was visible in this area. Numerous small rockfalls occurred on the SE flank, adding to the talus apron in the upper reaches of the Tar River valley. The sulfur-dioxide flux averaged 1,114 metric tons per day.
Source: Montserrat Volcano Observatory (MVO)
| 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 30 November to 12 December, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. There were no significant changes in seismicity or deformation during the report period. The well-established pattern of tiny "drumbeat" earthquakes continued at a rate of one every 1-2 minutes and other monitoring data remained in typical ranges. Despite the continuing procession of earthquakes, the overall seismic energy release was very low compared to that during early phases of the eruption. Small rockfalls continued from the growing lava dome, with larger ones producing ash plumes that were visible above the crater rim. The volume of the lava dome measured on 24 October was 70 million cubic meters-about 90% of the volume of the 1980-to-1986 dome. St Helens remained at Volcano Advisory (Alert Level 2); aviation color code Orange.
Source: US Geological Survey Cascades Volcano Observatory (CVO)
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.
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