Activity for the week of 8 August-14 August 2012
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
| Tonga Ridge
| 25.887°S, 177.188°W
| Elevation -132 m
According to Institute of Geological & Nuclear Sciences Limited (GNS) in a media release on 11 August, the Laboratoire de Géophysique (Papeete, Tahiti) reported that seismographs in Rarotonga recorded eruptive activity at Monowai seamount on 3 August. The activity then stopped overnight.
| 16.72°N, 62.18°W
| Elevation 915 m
MVO reported that during 3-10 August activity at the Soufrière Hills lava dome was mostly at a low level. The seismic network detected two small swarms of volcano-tectonic earthquakes on 7 and 8 August. Scientists at MVO observed a period of ash venting that began at 1700 on 8 August, less than two hours after the second swarm. Roaring sounds were heard at the same time. The ash plume drifted W over Plymouth at an altitude of about 1 km (3,280 ft) a.s.l., and a small amount of ashfall was reported by a fisherman offshore. The source of the venting appeared to be the gas vent in the floor of the 11 February 2010 collapse scar, and not the crater created on 23 March 2012.
On 9 August the inside of the collapse scar was partially visible during a helicopter flight. Fumarolic activity in the 23 March crater had increased compared to two weeks ago, and some other fumaroles were also more active. A change in wind direction shifted the volcanic plume N for much of the day and the odor of volcanic gas was noticeable in some inhabited areas. The Hazard Level remained at 2 (on a scale of 1-5).
Source: Montserrat Volcano Observatory (MVO)
| North Island (New Zealand)
| 39.157°S, 175.632°E
| Elevation 1978 m
GeoNet reported that favorable weather allowed GNS Science and Department of Conservation scientists to conduct an observation flight over Tongariro on 8 August. They noted actively steaming vents that were visible at a new crater area formed on 6 August below the Upper Te Mari crater, but low clouds prevented any views above this elevation. Blocks of old and hydrothermally altered lava, as large as 1 m in diameter, ejected by the eruption fell 1.5-2 km from the Te Mari craters area. Falling blocks formed impact craters in the ground in an extensive area to the E and W of the new vents. Most blocks were covered by grey ash but many on the W slopes were not, suggesting that they were ejected after the main ash-producing phase of the eruption.
The scientists also noted that previously steaming ground at Ketetahi and Lower Te Mari crater appeared more vigorous, but there were no obvious major changes. A debris flow generated by the eruption partly filled a stream valley draining N-W from the Upper Te Mari crater area. The deposit had blocked some stream tributaries but most water diverted around the edges. Ash had slumped from the banks into the stream valley, and in other stream valleys ash has been re-mobilized in slurry flows. No lahars were generated by the eruption.
New rock falls were visible around the walls of the new vent area and Lower Te Mari craters and in some stream valley walls near the craters. This suggested that significant ground shaking took place during the eruption. The Alert Level remained at 2 (on a scale of 0-5) and the Aviation Colour Code was lowered to Yellow (second lowest on a four-color scale).
During 8-9 August seismic activity remained at a low level; only a few small events were recorded. Preliminary analysis of the ash showed that there was little to no new magma erupted. Gas analysis on 9 August revealed emissions around 2,100 tonnes per day of sulfur dioxide, 3,900 tonnes per day of carbon dioxide, and 364 tonnes per day of hydrogen sulfide, confirming the presence of magma below the volcano. During an overflight on 9 August scientists observed minor ash emissions from the vents. Seismicity continued to remain low during 10-14 August. Heavy rains on 12 August caused a lahar to cross State Highway 46, approximately 6 km W of Rangipo.
| North Island (New Zealand)
| 37.52°S, 177.18°E
| Elevation 294 m
The GeoNet Data Centre reported that scientists visited White Island on 9 August and observed an ash plume rising as high as 300 m from a new vent in the SW corner of the 1978/1990 Crater Complex. Black ash was depositing on the wall of the Main Crater to the W of the vent. The vent had started to build a tuff cone and there were impact craters around it created by ejecta from explosions. There was no sign of impact craters or blocks outside of the 1978/1990 Crater area. During 9-14 August volcanic tremor remained at low levels and a weak ash-and-steam plume rose a few hundred meters from the vent. The plume color changed between white and gray as the ash content varied. On 13 August the Alert Level remained at 2 (on a scale of 0-5), and the Aviation Colour Code was lowered to Yellow (second lowest on a four-color scale).
| Kyushu (Japan)
| 31.593°N, 130.657°E
| Elevation 1117 m
JMA reported that during 6-10 August nine explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. Based on information from JMA, the Tokyo VAAC reported that explosions during 8-14 August often produced plumes that rose to altitudes of 1.8-3.7 km (6,000-12,000 ft) a.s.l. and drifted N and NE. A pilot observed an ash plume on 8 August.
Sources: Tokyo Volcanic Ash Advisory Center (VAAC), Japan Meteorological Agency (JMA)
| Komba Island (Indonesia)
| 7.791°S, 123.585°E
| Elevation 633 m
Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 11-14 August ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 25-75 km NW and W.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| Chuginadak Island (USA)
| 52.825°N, 169.944°W
| Elevation 1730 m
AVO reported that during 8-11 August elevated surface temperatures from Cleveland were detected in partly-cloudy satellite images. Cloud cover prevented observations on 12 August. Nothing unusual was observed in images during 13-14 August. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.
Source: US Geological Survey Alaska Volcano Observatory (AVO)
| 14.473°N, 90.88°W
| Elevation 3763 m
INSIVUMEH reported that during 9-10 and 13-14 August explosions from Fuego produced ash plumes that rose 300-400 m above the crater and drifted NW and W. Degassing sounds were reported, and diffuse white plumes rose 100-150 m and drifted NE and NW. Lava flows traveled 200-250 m down the Taniluyá drainage (SW), generating block avalanches that reached vegetated areas. On 10 August lahars 25 m wide traveled SE down the Las Lajas and El Júte drainages carrying blocks 1-2 m in diameter. Explosions during 13-14 August ejected incandescent tephra 100 m above the crater.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
| 1.22°N, 77.37°W
| Elevation 4276 m
INGEOMINAS reported that during 8-14 August seismicity at Galeras continued to be elevated. Some of the earthquakes were located near the active cone, with magnitudes less than 1 and depths not exceeding 2 km. During 7-9 and 11 August gas-and-ash plumes rose 0.9-1.3 km above the crater and drifted W and S. Sulfur dioxide emissions fluctuated between moderate and high levels. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
Source: Servicio Geológico Colombiano (SGC)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
KVERT reported moderate seismic activity from Karymsky during 3-10 August. Satellite imagery showed a weak thermal anomaly on the volcano. A possible gas-and-ash explosion on 8 August may have produced a plume that rose to an altitude of 3.3 km (10,800 ft) a.s.l. The Aviation Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 8-14 August HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Measurements indicated that the gas plume from the vent continued to deposit variable amounts of spatter and Pele's hair onto nearby areas. There were no significant geologic changes in Pu'u 'O'o Crater; a few days before 11 August a new glowing vent SE of the crater appeared, probably from a newly-opened skylight in the lava-tube system feeding flows on the pali and coastal plain. Lava flows were active on the pali and the coastal plain. The active lava-flow front was about 2 km from the ocean on 14 August.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Nevado del Ruiz
| 4.892°N, 75.324°W
| Elevation 5279 m
According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that during 10-13 August low levels of tremor were detected at Nevado del Ruiz, possibly associated with continuing gas and ash emissions. On 12 August a total of 140 low-magnitude earthquakes (M < 1.8) were detected in a seismic swarm that began at 0956 and ended at 1800. The earthquakes were located about 4 km WSW of Arenas Crater at depths of less than 5 km. A gas-and-ash plume observed with a web camera rose 1 km above the crater and drifted W. Ashfall was reported in Brisas (50 km SW). Satellite images showed continuing sulfur dioxide emissions. On 13 August a seismic swarm was characterized by events less than M 1, and located NE of Arenas Crater at depths between 3 and 5 km. A thin layer of ash was deposited at the observatory in Manizales. Weather conditions prevented observations of the volcano. The Alert Level remained at II (Orange; "eruption likely within days or weeks").
Source: Servicio Geológico Colombiano (SGC)
| 19.023°N, 98.622°W
| Elevation 5393 m
CENAPRED reported that during 8-14 August seismicity at Popocatépetl indicated continuing gas-and-steam emissions that may have contained ash on 8 August; cloud cover prevented observations during most of this period. Incandescence from the crater was periodically observed. Gas-and-steam plumes were observed rising from the crater during 8-9 and 14 August. A small ash emission was observed on 14 August. The Alert Level remained at Yellow, Phase Three.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
| 0.077°S, 77.656°W
| Elevation 3562 m
Based on analysis of satellite imagery, the Washington VAAC reported a possible ash emission from Reventador on 11 August. The next day a well-defined thermal anomaly was detected and an ash plume drifted W. According to the VAAC, IG confirmed the ash plume, noting that it rose to an altitude of 5.2 km (17,000 ft) a.s.l.
Source: Washington Volcanic Ash Advisory Center (VAAC)
| Central Kamchatka (Russia)
| 56.653°N, 161.36°E
| Elevation 3283 m
KVERT reported that during 3-10 August weak seismic activity was detected at Shiveluch. Cloud cover prevented ground-based observations; however, a thermal anomaly on the volcano was detected daily in satellite imagery. The Aviation Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Sulawesi (Indonesia)
| 1.112°N, 124.737°E
| Elevation 1785 m
According to NASA's Earth Observatory, a satellite image acquired on 8 August showed a small volcanic plume rising from Soputan.
Source: NASA Earth Observatory
| 1.467°S, 78.442°W
| Elevation 5023 m
IG reported that during 8-13 August visual observations of Tungurahua were limited due to cloud cover. A vapor emission drifted W on 8 August. A small explosion on 10 August vibrated windows, and ash fell in Choglontús (SW). Three to four explosions on 11 and 12 August produced "gun shot" noises. At night incandescence from the crater was observed and sounds resembling blocks rolling down the flanks were reported. On 11 August an ash-and-steam plume rose from the crater, and the next day an ash plume rose 1 km and drifted W. During 12-13 August incandescent blocks were ejected 100 m above the crater and rolled 500 m down the flanks. Roaring was heard and ash fell in Cusúa (8 km NW) and Juive (7 km NNW). On 14 August seismicity increased and was accompanied by increased emissions. Ashfall was reported in Pillate (7 km W), Cusúa, and Choglontús.
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.
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