Activity for the week of 25 April-1 May 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
| Komba Island (Indonesia)
| 7.791°S, 123.585°E
| Elevation 633 m
Based on analyses of satellite imagery, the Darwin VAAC reported that during 25-26 April ash plumes from Batu Tara rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 37 km W and SW. During 30 April-1 May ash plumes again rose to an altitude of 2.4 km (8,000 ft) a.s.l. then drifted 37-55 km NW.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| Chuginadak Island (USA)
| 52.825°N, 169.944°W
| Elevation 1730 m
AVO reported that elevated surface temperatures were detected over Cleveland in satellite imagery during 25-29 April and possibly on 30 April. Observations showed that a small lava dome, 25 m across, had recently been emplaced.
Source: US Geological Survey Alaska Volcano Observatory (AVO)
| 24.751°N, 141.289°E
| Elevation 169 m
According to a JMA report on 2 May, an eruption at Ioto (Iwo-jima) caused water discoloration to the NE. A new fumarole was also confirmed.
Source: Japan Meteorological Agency (JMA)
| Sulawesi (Indonesia)
| 1.358°N, 124.792°E
| Elevation 1580 m
According to the Darwin VAAC, ash plumes from Lokon-Empung, that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 75 km N, were detected in satellite imagery and reported by ground-based observers.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
| 19.023°N, 98.622°W
| Elevation 5393 m
CENAPRED reported that gas-and-steam plumes, occasionally containing ash, rose from Popocatépetl during 25-29 April. Gas-and-ash plumes rose 1.5 km above the crater on 25 and 27 April. On 28 April incandescent fragments ejected from the crater landed on E flank as far as 1 km. The next day steam-and-gas plume rose from the crater. On 1 May gas-and-steam plumes, that occasionally contained low amounts of ash, and rose 1 km above the crater. The Alert Level remained at Yellow Phase Three.
Source: Centro Nacional de Prevencion de Desastres (CENAPRED)
| Kyushu (Japan)
| 31.593°N, 130.657°E
| Elevation 1117 m
Based on information from JMA, the Tokyo VAAC reported that during 24 April-1 May explosions from Sakura-jima produced plumes that rose to altitudes of 1.8-2.7 km (6,000-9,000 ft) a.s.l. and drifted in multiple directions. A pilot observed an ash plume on 26 April that rose to an altitude of 2.7 (9,000 ft) a.s.l.
Source: Tokyo Volcanic Ash Advisory Center (VAAC)
| Luzon (Philippines)
| 12.769°N, 124.056°E
| Elevation 1535 m
PHIVOLCS reported that the Alert Level for Bulusan was lowered to 0 (on a scale of 0-5) on 24 April following a decline in activity after a phreatic eruption on 13 May 2011. The frequency of earthquakes decreased to baseline levels of 0-2 per day, measurements indicated deflation since late November 2011, and steaming activity from the crater and known thermal vents had been frequently weak compared to more moderate steam emissions during periods of unrest. Entry into the permanent danger zone, defined by a 4-km radius around the volcano, remained prohibited.
Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)
| Sicily (Italy)
| 37.748°N, 14.999°E
| Elevation 3320 m
Sezione di Catania - Osservatorio Etneo reported that the twenty-fifth paroxysmal eruptive episode since January 2011 took place at New SE Crater (New SEC) of Etna during the morning of 24 April following about 11 days of quiescence. During 21-22 April a series of small ash emissions observed by web cameras drifted downslope to the E. On 22 April prolonged emissions of white vapor rose from an area in the upper portion of the fissure that cuts the SE flank of the cone. At night several incandescent spots were visible on the NE and S crater rims, where hot gas heated the surrounding rocks. On 23 April a small thermal anomaly in the area of New SE Crater was produced by a tiny lava flow, which issued from the same vent that had produced the prolonged vapor emissions on the previous day. The lava flow slowly advanced a few hundred meters toward the Valle del Bove, but stagnated on the W rim. Another lava flow was produced later that day.
At around 1800 the effusive vent started to vigorously spatter. A second vent became active a few tens of meters further upslope, which initially ejected spatter, but activity rapidly evolved into frequent Strombolian explosions accompanied by a slow rise in the volcanic tremor amplitude. During the following hours, sporadic explosions were also observed from a vent located within the New SEC; the activity remained more or less consistent, while the volcanic tremor amplitude fluctuated at only slightly elevated levels. At 0210 0n 24 April the Strombolian activity showed a marked increase and turned into sustained lava fountaining at 0230. A plume with a heavy load of ash and lapilli rose a few kilometers, drifted NE, and produced ashfall 15-17 km NE in Linguaglossa, Piedimonte, and Presa. The upper part of the plume drifted E and produced pea-sized lapilli fall in the area between Fornazzo (10 km E) and Giarre (17 km E). The phase of most intense lava fountaining lasted approximately 25 minutes, from 0240 until 0305 on 24 April, after which the intensity rapidly decreased and returned to Strombolian activity, before ceasing completely around 0340.
Source: Sezione di Catania - Osservatorio Etneo (INGV)
| Eastern Kamchatka (Russia)
| 54.049°N, 159.443°E
| Elevation 1513 m
KVERT reported that moderate seismic activity from Karymsky continued to be detected during 20-27 April, and indicated that possible ash plumes rose to an altitude of 2.5 km (8,200 ft) a.s.l. during 20 and 24-25 April. Satellite imagery showed a daily thermal anomaly on the volcano. 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 April-1 May HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Frequent measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash, and occasionally fresh spatter, nearby. Incandescence was visible from both a lava pond in a small pit on the E edge and a small spatter cone on the SE edge of the Pu'u 'O'o crater floor, and on the upper part of the lava-tube system on the E flank. Lava flows continued to advance down the pali and across the coastal plain, reaching about 900 m from the coast. New lava flows on the pali were observed on 30 April, while web cameras recorded decreasing incandescence on the coastal plain during 30 April-1 May.
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 25-26 and 28-30 April video data and observers in the city of Manizales (25 km NW) indicated that gas-and-steam plumes rose 0.5-2 km above Nevado del Ruiz's crater. Cloud cover prevented observations on 27 April. Seismic signals indicated that an ash plume was emitted at 1248 on 30 April however cloud cover prevented observations. Seismicity fluctuated, but decreased. The Alert Level remained at II (Orange; "eruption likely within days or weeks").
Source: Servicio Geológico Colombiano (SGC)
| 14.757°N, 91.552°W
| Elevation 3745 m
INSIVUMEH reported that on 25 April a lahar traveled down Santa María's Rio Nima II drainage, carrying 1.5-m-wide blocks and tree branches. During 30 April-1 May white plumes rose 300-600 m above the lava dome. Lava flows continued to produce avalanches that descended the flanks. Ashfall was reported in Quetzaltenango (18 km WNW) and surrounding areas.
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 explosive activity at Shiveluch continued during 20-27 April. Ground-based observers and satellite imagery indicated that a viscous lava flow continued to effuse in the crater formed during a 2010 eruption and was accompanied by fumarolic activity. Seismic data and visual observations showed that ash plumes rose to an altitude greater than 10 km (32,800 ft) a.s.l. on 24 April and were slight on the other days. Satellite imagery showed a weak thermal anomaly on the lava dome during 20-22 April, and ash plumes that drifted 396 km NE on 24 April. The Aviation Color Code remained at Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| 16.72°N, 62.18°W
| Elevation 915 m
MVO reported that during 20-27 April activity at the Soufrière Hills lava dome was at a low level. Observations on 24 April revealed fresh rockfall and pyroclastic flow deposits SW, at the head of Gingoe's Ghaut. The Hazard Level remained at 2.
Source: Montserrat Volcano Observatory (MVO)
| 1.467°S, 78.442°W
| Elevation 5023 m
IG reported that during 25-30 April visual observations of Tungurahua were occasionally limited due to cloud cover. On 27 April a steam-and-ash plume rose 200 m above the crater and drifted WNW. On 30 April tremor was detected then followed by an ash plume that rose 4 km above the crater and drifted WNW. Ash fell in Manzano (8 km SW), Choglontus (SW), and Cahuají (8 km SW). At night observers in the SW noted incandescent blocks that that traveled 1.5 km down the flank. On 1 May steam-and-ash plumes drifted W producing ashfall in Bilbao (8 km W), Motilones (W), Cotaló (8 km NW), Pillate (7 km W), Chacuaco, Choglontus, Cahuají, and Manzano.
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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