Activity for the week of 25 July-31 July 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
| 0.95°N, 77.87°W
| Elevation 4764 m
According to INGEOMINAS, the Observatorio de Pasto reported that during 25-31 July seismic signals related to movement of fluid decreased compared to the previous week; earthquake swarms were detected on 26, 27, 29, and 30 July. The number and magnitude of earthquakes generated by fracturing rock increased. Four of the events were located SW of the volcano at a depth of 10 km, and less than M 2.1. Weather conditions prevented observations of the volcano. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").
Source: Servicio Geológico Colombiano (SGC)
| North Island (New Zealand)
| 39.157°S, 175.632°E
| Elevation 1978 m
On 31 July GeoNet reported that seismicity at Tongariro had declined the previous week but increased again during 28-29 July, and as of 31 July, between 3 and 10 events were being recorded daily. The earthquakes were clustered in a zone between Tongariro and the E side of Lake Rotoaira, at 2-7 km depth. The Alert Level remained at 1 (on a scale of 0-5) and the Aviation Colour Code remained at Yellow (on a four-color scale).
| 19.532°S, 169.447°E
| Elevation 361 m
Following an assessment during 7-12 July, the Geohazards Observatory team concluded that explosive activity at Yasur had slightly increased, becoming stronger and more frequent, and shifting from Strombolian to sub-Plinian. Bombs ejected from the vents fell in the crater, around the summit area, and on the tourist walk and parking area. The explosions were heard, felt, and observed from nearby villages and schools. Activity at all three volcanic vents was characterized by degassing, ash emissions, and ejection of bombs. On 13 July the Alert Level was raised to 3 (on a scale of 0-4).
Source: Vanuatu Meteorology and Geo-Hazards Department (VMGD)
| Kyushu (Japan)
| 31.593°N, 130.657°E
| Elevation 1117 m
JMA reported that during 24-27 July twenty explosions from Sakura-jima's Showa Crater ejected tephra as far as 1,300 m from the crater. An explosion on 26 July produced a large ash plume. Based on information from JMA, the Tokyo VAAC reported that explosions during 25-26 and 28-31 July produced plumes that rose to altitudes of 1.5-3.7 km (5,000-12,000 ft) a.s.l. and drifted SW, W, NW, and N. Pilots observed ash plumes during 25-26 and 29 July that rose to altitudes of 2.4-3.4 km (8,000-11,000 ft) a.s.l.
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 24-31 July ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 37-110 km W, NW, and N.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| Chuginadak Island (USA)
| 52.825°N, 169.944°W
| Elevation 1730 m
AVO reported that cloud cover mostly prevented satellite and web camera observations of Cleveland during 25-31 July. Slightly elevated surface temperatures were detected in satellite images during 25-26 and 29-30 July. 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 26-27 and 29-31 July explosions from Fuego produced ash plumes that rose 200-500 m above the crater and drifted NW, W, and SW. Fumarolic plumes drifted the same direction. Explosions ejected incandescent tephra 100 m above the crater. Lava flows traveled 300 m down the Taniluyá drainage (SW) and 150 m down the Ceniza drainage (SSW); detached blocks from both lava-flow fronts produced incandescent avalanches.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
KVERT reported moderate seismic activity from Karymsky during 20-27 July. Satellite imagery showed a weak thermal anomaly on the volcano on 22 and 25 July. 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 25-31 July 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. The lava pond in a small pit on the E edge of the Pu'u 'O'o crater floor and two vents along the S edge of the floor were visible with the web cameras. Lava flows were active on the pali and the coastal plain; the active lava-flow front was about 1.8 km from the ocean on 31 July.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| Papua New Guinea
| 4.08°S, 145.037°E
| Elevation 1807 m
RVO reported that activity at Manam increased slightly during 15-31 July, except from 18 to 20 July when there were fewer ash emissions. During most of the reporting period, when visibility was clear, gray-to-sometimes-black ash plumes were observed rising 300-700 m above the crater from two vents and drifting NW. Rumbling was often heard on the island; rumbling on 25 July was heard on the mainland 25 km SW. Bright glow visible at night was attributed to ejected incandescent tephra. Sub-Plinian activity occurred on most nights during 21-31 July. Small lava flows descended the SW flank. Four pyroclastic flows traveled down the SE flank on 30 July at 0638, 0640, during 1200-1300, and at 1428. The first event was the largest, and generated an ash plume that rose 1.8 km above the crater and drifted NW. Emissions from Main Crater were milder and mostly characterized by white and bluish plumes, and occasional gray ash plumes.
Source: Rabaul Volcano Observatory (RVO)
Nevado del Ruiz
| 4.892°N, 75.324°W
| Elevation 5279 m
According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that on 31 July web cameras at Nevado del Ruiz showed gas-and-ash plumes rising 300 m above the crater. Seismicity was low. The Alert Level remained at II (Orange; "eruption likely within days or weeks").
Source: Servicio Geológico Colombiano (SGC)
| Mariana Islands (USA)
| 18.13°N, 145.8°E
| Elevation 570 m
Minor steam-and-gas plumes from Pagan were observed in satellite images during clear periods from 20 to 27 July. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.
Source: Emergency Management Office of the Commonwealth of the Mariana Islands and United States Geological Survey Volcano Hazards Program
| 19.023°N, 98.622°W
| Elevation 5393 m
CENAPRED reported that during 25-31 July seismicity at Popocatépetl indicated continuing gas-and-ash emissions that sometimes probably contained ash; cloud cover prevented observations during most of this period. Incandescence from the crater was periodically observed. Steam-and-gas plumes were observed daily rising from the crater as high as 1.5 km above the rim. The plumes drifted in multiple directions. The Alert Level remained at Yellow, Phase Three.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
| 2.005°S, 78.341°W
| Elevation 5286 m
According to the Washington VAAC, a pilot reported that on 29 July an ash plume from Sangay rose to an altitude of 6.7 km (22,000 ft) a.s.l. and drifted W. A plume that may have been mostly gas was detected in satellite images pushing through the metrological cloud deck and drifting W.
Source: Washington Volcanic Ash Advisory Center (VAAC)
| 14.757°N, 91.552°W
| Elevation 3745 m
INSIVUMEH reported that during 26-27 July an explosion from Santa María's Santiaguito lava-dome complex produced an ash plume that rose 400 m above Caliente dome. White gas plumes rose 200 m and drifted SW; incandescence from the crater was reflected in the plume. On 29 July pyroclastic flows descended the S flank and generated ash plumes that rose 1.5 km above the crater and drifted 15 km SW. The next day explosions produced ash plumes that rose 1.5 km and drifted 12 km WSW. During 30-31 July explosions produced ash plumes that rose 1.5 km above Caliente dome and drifted 12 km WSW. Block avalanches on the S flank generated pyroclastic flows that traveled to the base of the volcano.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
| Central Kamchatka (Russia)
| 56.653°N, 161.36°E
| Elevation 3283 m
KVERT reported that during 20-29 July explosive activity was detected at Shiveluch and observers noted gas-and-steam activity. Satellite imagery showed a thermal anomaly on the lava dome during 20, 22-26, and 28-29 July. Based on information from KEMSD and analyses of satellite images, the Tokyo VAAC reported that on 27 July an eruption produced an ash plume that rose to an altitude of 10.1 km (33,000 ft) a.s.l. The Aviation Color Code remained at Orange.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)
| 1.467°S, 78.442°W
| Elevation 5023 m
IG reported that during 25-31 July visual observations of Tungurahua were limited due to cloud cover. On 25 July incandescence from the crater was observed at night, an explosion generated a "cannon shot" noise, and there were sounds resembling blocks rolling down the flanks. The next day a steam plume rose 200 m above the crater and drifted W. The Juive (NNW), La Pampa (S), and Mapayacu (SW) drainages contained muddy waters on 29 July; water on the Mapayacu drainage carried blocks that were 50 cm in diameter. An explosion on 30 July produced sounds resembling rolling blocks and caused vibrating windows in surrounding areas. One small explosion was detected on 31 July.
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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