Activity for the week of 10 August-16 August 2011
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
| Chuginadak Island (USA)
| 52.825°N, 169.944°W
| Elevation 1730 m
On 9 August AVO reported that possible thermal anomalies on Cleveland were detected in satellite imagery. Cloud cover prevented observations of the summit area during 10-12 and 15-16 August, but several thermal anomalies were visible during 13-14 August. A scientist that flew 32 km N of the volcano on 14 August observed small white "puffs" of steam rising 30-60 m above the summit, even though most of the volcano was obscured by clouds. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange. No current seismic information was available because Cleveland does not have a real-time seismic network.
Source: US Geological Survey Alaska Volcano Observatory (AVO)
| Halmahera (Indonesia)
| 1.693°N, 127.894°E
| Elevation 1229 m
According to a news article, activity at Dukono had continued to increase. On 11 August ash explosions were audible within a radius of about 7 km from the base of the volcano. Ash was ejected as high as 1 km above the crater, producing plumes that drifted E and S, and also approached Tobelo City (14 km ENE). Seismographs at the Dukono observation post recorded more than 100 eruption earthquakes. Based on analyses of satellite imagery, the Darwin VAAC reported that on 11 and 14 August ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 93 km NW.
Sources: Darwin Volcanic Ash Advisory Centre (VAAC), Metro TV News
| Sicily (Italy)
| 37.748°N, 14.999°E
| Elevation 3295 m
Sezione di Catania - Osservatorio Etneo reported that on 11 August sporadic ash emissions from Etna's New SE Crater produced small grayish-brown ash plumes. Thermal surveillance cameras revealed hot material in late-afternoon emissions. In the evening and throughout the night small Strombolian explosions were observed at intervals of a few tens of minutes. Early on 12 August, the day of the tenth paroxysmal eruptive episode of 2011, the Strombolian activity intensified and was accompanied by an increase in volcanic tremor amplitude. Strombolian explosions then produced dark ash clouds, and lava overflowed the E rim of the crater through a deep breach formed during previous eruptions. During the following 30 minutes or so Strombolian activity rapidly intensified, and formed a pulsating lava fountain about 100 m tall. Fifteen minutes later a dense column of ash rose above the lava fountain while large bombs and blocks fell onto the cone surrounding the New SE Crater.
During the most intense period three vents in the crater were active, two in the central portion and one close to the E-rim breach. Soon after, the two vents in the center of the crater emitted only ash, while the E vent continued to eject jets of incandescent lava. The activity completely ceased more than a half an hour later. The lava produced during the eruption descended the W slope of the Valle del Bove in numerous lobes; the most advanced lava fronts reached the base of the steep slope above Monte Centenari. Ash- and lapilli-fall affected a relatively narrow area between Zafferana (10 km SE), and the coastal area between Giarre and Acireale, on the SE flank.
Source: Sezione di Catania - Osservatorio Etneo (INGV)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 10-16 August HVO reported that Kilauea's summit lava lake was mostly crusted, but lava, possibly from a source higher on the SE wall, occasionally flowed over the surface. Small rockfalls from the vent walls were frequent, and the gas plume from the vent continued to deposit variable amounts of ash and occasionally fresh spatter nearby. During an overflight on 11 August, scientists observed an E-W trench in the deepest part of the cavity. Lava was upwelling from the E end and flowing W. During 14-15 August hot and possibly spattering vents were visible on the W part of the cavity floor.
At the E-rift zone, lava continued to trickle onto Pu'u 'O'o's collapsed crater floor and some spattering occurred from various sources the floor. The W-flank vents remained active and fed an elongated perched lava pond that extended to the SW, and also a small flow which advanced a short distance N. Small overflows or breaches from the elongated lake were occasionally active on the N side. During the 11 August overflight, scientists noted that the activity was less vigorous; the two channels that continued to feed the perched lake were crusted over and the W-flank vents were no longer spattering. The pond rims were higher and the pond was narrower, lava flows from the base of the pond were active on the N and W sides of the pond, and the S rim of the pond appeared to be slowly migrating S. The crater floor subsided a small amount on 15 August.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| 0.38°S, 100.474°E
| Elevation 2885 m
According to a news article, two eruptions from Marapi occurred on 9 August. The article also noted that the Alert Level remained at 2 (on a scale of 1-4).
Source: Metro TV News
| Western Java (Indonesia)
| 7.32°S, 107.73°E
| Elevation 2665 m
On 13 August CVGHM reported that based on seismicity, deformation, geochemistry, and visual observations, the Alert Level for Papandayan was raised to 3 (on a scale of 1-4). During 1 June-12 August sulfur plumes rose 20-75 m above the vents. During the same period, seismicity increased with several hundreds of earthquakes detected per month. Temperature measurements in the Manuk thermal area indicated a relative increase from 29 June to 12 August and deformation measurements indicated inflation from 4 July to 10 August. Visitors and residents were not to venture within 2 km of the active crater.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
| New Britain (Papua New Guinea)
| 4.271°S, 152.203°E
| Elevation 688 m
RVO reported a decline in frequency of ash emission from Rabaul caldera's Tavurvur cone during 9-12 August, and no distinct explosions were detected. Ash-rich plumes rose 1 km above the crater and drifted NW, causing ashfall in Rabaul town (3-5 km NW) and in areas between Toliap (10 km NW) and Tavui. Seismicity was very low, consisting of sub-continuous volcanic tremor associated with the ash emissions and some small discrete low-frequency earthquakes. Ash emissions ceased on 12 August. During 13-15 August white vapor plumes rose from the crater.
Source: Rabaul Volcano Observatory (RVO)
| Sulawesi (Indonesia)
| 1.112°N, 124.737°E
| Elevation 1785 m
CVGHM reported that during 19 July-13 August white plumes from Soputan's summit crater rose 50-150 m. Seismicity fluctuated, but declined overall until 10 August. On 14 August a gray-and-white eruption plume rose 1 km above the crater. Throughout the day, two more similar plumes rose 1.3 km above the crater. Based on analysis of satellite imagery, the Darwin VAAC reported that an ash plume drifted more than 100 km W. The Alert Level was raised to 3 (on a scale of 1-4). Visitors and residents were prohibited from going within a 6-km radius of the crater.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)
| Kyushu (Japan)
| 31.593°N, 130.657°E
| Elevation 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 10-16 August explosions from Sakura-jima produced plumes that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. On 12 August, a pilot observed an ash plume that rose to an altitude of 2.4 km (8,000 ft) a.s.l.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
KVERT reported that during 5-12 August moderate seismic activity continued at Karymsky and possible ash plumes rose to an altitude of 3 km (9,800 ft) a.s.l. A thermal anomaly on the volcano was detected daily by satellite. During 7-8 August, pilots observed ash plumes that rose to an altitude of 4 km (13,100 ft) a.s.l. and drifted E. Satellite imagery also showed an ash cloud, 3 by 1.5 km in dimension, that was 10 km W of the volcano on 10 August. The Aviation Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Eastern Kamchatka (Russia)
| 55.131°N, 160.32°E
| Elevation 2334 m
KVERT reported that during 5-12 August seismicity from Kizimen was above background levels and weak volcanic tremor continued to be detected. Video images showed fumarolic activity and an occasional steam-and-gas plume that rose to an altitude of 4 km (13,100 ft) a.s.l. A lava flow on the E flank remained active. Satellite images showed a bright thermal anomaly on the volcano all week. The Aviation Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| 19.023°N, 98.622°W
| Elevation 5393 m
CENAPRED reported that late on 9 August an ash plume from Popocatépetl rose 1 km above the crater and drifted W. During 11-12 August steam-and-gas emissions occasionally contained small amounts of ash.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
| 40.59°S, 72.117°W
| Elevation 2236 m
During 10-14 August, OVDAS-SERNAGEOMIN reported that the eruption continued from the Cordón Caulle rift zone, part of the Puyehue-Cordón Caulle volcanic complex. Cloud cover prevented video camera observations during 10-12 August and satellite observations during 10-11 August. A diffuse plume detected in satellite imagery on 12 August drifted 150 km E. On 14 August a gray plume recorded by the camera rose 2 km above the crater, and satellite imagery showed a plume drifting 100-150 km E and SE. The Alert Level remained at Red, indicating that ashfall and lahars remain a hazard.
Source: Servicio Nacional de Geología y Minería (SERNAGEOMIN)
| Central Kamchatka (Russia)
| 56.653°N, 161.36°E
| Elevation 3283 m
KVERT reported that seismicity at Shiveluch was moderate during 5-12 August. Seismic data indicated that possible ash plumes rose to an altitude of 6.7 km (22,000 ft) a.s.l. on 8 August, to an altitude of 6 km (19,700 ft) a.s.l. on 10 August, and to altitudes of 4-5.5 km (13,100-18,000 ft) a.s.l. on other days. Ground-based observers indicated that ash plumes rose to an altitude of 7 km (23,000 ft) a.s.l. on 6 August. Satellite imagery showed a daily thermal anomaly on the lava dome, and ash plumes that drifted 60 and 20 km SE on 6 and 10 August, respectively. The Aviation Color Code remained at Orange.
Based on analysis of satellite imagery, the Tokyo VAAC reported that on 13 August a possible eruption produced a plume that rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted W. Ash was seen in subsequent satellite images that same day. An eruption on 15 August produced a plume that rose to an altitude of 7.9 km (26,000 ft) a.s.l.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo 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.
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