Activity for the week of 20 August-26 August 2003
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
| 11.538°N, 85.622°W
| Elevation 1700 m
According to news articles, INETER reported increased seismicity at Concepción on 21 August. People on the island of Ometepe did not feel the tremor, which ended on 22 August.
Sources: La Prensa (Nicaragua), El Nuevo Diario
| Grand Comore Island
| 11.75°S, 43.38°E
| Elevation 2361 m
According to news reports, Observatoire Volcanologique du Karthala scientists noted a steady increase in seismicity at Karthala over the past 3 months. Around 100 earthquakes occurred per day in August in comparison to 1-2 per day in June.
Sources: Reuters, Agence France-Presse (AFP)
Piton de la Fournaise
| Reunion Island (France)
| 21.244°S, 55.708°E
| Elevation 2632 m
Following 5 months of slow inflation at Piton de la Fournaise and a series of eruptions during May to July, a new period of heightened seismicity began beneath Dolomieu crater on 23 August at 1848. The first fissure opened in Bory crater around 2120, and the second fissure opened at 2210 on the N flank at about 2,450 m altitude. Both fissures were active for short periods of time. The final fissure opened at 2330 around 2,200 m altitude on the N flank. A lava flow traveled into Plaine des Osmondes.
Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)
| 1.467°S, 78.442°W
| Elevation 5023 m
After 50 days of low activity, Tungurahua entered a new phase of activity on 20 August, characterized by a short sequence of long-period earthquakes followed by gas-and-ash emissions that reached a maximum height of 3 km above the volcano. A small amount of ash fell in the sector of Cusúa. During the evening incandescent volcanic blocks were hurled ~300 m above the volcano and traveled ~1 km down the volcano's flanks. On 21 August emissions of mostly steam and small amounts of ash rose ~1 km above the volcano and drifted W. Ash fell in the sectors of Riobamba, Ambato, and Santa Fé de Galán. On 23 August plumes rose to 0.5-2.5 km above the volcano, and ash fell in the town of Guaranda. On 24 August an explosion at 2133 ejected blocks that traveled ~1 km down the volcano's flanks. The explosion was heard in the town of Baños.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC), Agence France-Presse (AFP)
| Halmahera (Indonesia)
| 1.693°N, 127.894°E
| Elevation 1229 m
On 26 August an ash plume from Dukono was visible on satellite imagery at a height of ~3 km a.s.l. extending ~55 km E of the summit.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| Sicily (Italy)
| 37.748°N, 14.999°E
| Elevation 3320 m
INGV-CT reported that on 11 August at 1715 an increase in volcanic tremor at the summit seismic stations on Etna lasted about 15 minutes. The tremor was followed by about 30 minutes of strong explosion earthquakes that were recorded at all INGV-CT seismic stations. This was the first such event recorded since the end of the flank eruption on 28 January 2003. A red puff of ash from Northeast Crater was visible on a INGV-CT web camera located at Milo, about 11 km from the summit. Red glow from the crater was seen during the night. No explosive activity or loud sounds occurred during a field survey on 14 August, and no explosion earthquakes or tremor were recorded during 11-16 August. Periodic measurements of the gas plume at the volcano's summit revealed that gas emissions had generally decreased since the end of the flank eruption.
Source: Sezione di Catania - Osservatorio Etneo (INGV)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 20-25 August at Kilauea, surface lava flows were visible on the coastal flat and upslope on the Holei Pali. Generally, seismicity at Kilauea's summit continued at moderate levels, with 1-2 small low-frequency earthquakes per minute occurring at shallow depths beneath the summit caldera. There were some larger events at depths of a few kilometers. Small inflation and deflation occurred several times during the report week.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| Central Kamchatka (Russia)
| 56.056°N, 160.642°E
| Elevation 4754 m
During 15-22 August, seismicity was above background levels at Kliuchevskoi. Up to 15 earthquakes were recorded per day at depths around 30 km. Spasmodic tremor was also recorded. Gas-and-steam plumes rose to 700 m above the volcano, weak fumarolic activity was recorded, and a thermal anomaly was visible on satellite imagery. Kliuchevskoi remained at Concern Color Code Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Eastern Java (Indonesia)
| 8.108°S, 112.922°E
| Elevation 3657 m
During 11-17 August, volcanic activity at Semeru continued at relatively high levels. Explosions produced ash columns that rose to 400 m above the summit. Seismicity was dominated by 550 explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)
| 16.72°N, 62.18°W
| Elevation 915 m
Volcanic and seismic activity at Soufrière Hills remained at relatively low levels during 15-22 August. Views of the lava dome inside the explosion crater showed that no further growth had occurred. Some very small rockfalls were produced from the interior of the 12 July collapse scar, and in several places large fumaroles formed. Sulphur-dioxide emissions ranged from 400 to 900 tonnes per day, with the maximum being recorded on 18 August.
Source: Montserrat Volcano Observatory (MVO)
| Aeolian Islands (Italy)
| 38.789°N, 15.213°E
| Elevation 924 m
INGV-CT reported that after the effusive eruption at Stromboli ceased between 21 and 22 July, explosive Strombolian activity became more common at both summit craters. Four active vents were observed within Crater 1 (the NE crater), and one funnel-shaped incandescent depression was seen within Crater 3 (the SW crater). Strombolian activity during the first half of August was very intense at Crater 1, with spattering that led to the creation of a spatter cone on the crater floor and fallout of incandescent bombs on the cone's outer flanks. Explosive activity at Crater 3 appeared to be deeper than at Crater 1 and was often accompanied by ash emission. During the first half of August thermal images of the apparently inactive flow field revealed a thermal signature within cracks on the upper flow field and within skylights along two lava tubes in the upper Sciara del Fuoco, at about 550 m elevation. Temperatures over 300°C and incandescence at these hot spots suggest endogenous growth of the apparently inactive lava flow field. Incandescence and thermal signatures at these sites were not seen between 22 and 31 July.
Source: Sezione di Catania - Osservatorio Etneo (INGV)
News Feeds and Google Placemarks
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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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