Activity for the week of 14 August-20 August 2002
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
Asosan
| Kyushu (Japan)
| 32.884°N, 131.104°E
| Elevation 1592 m
During 5 August to at least 15 August, isolated volcanic-tremor events occurred at Naka-dake, Aso's historically-active intra-caldera cone. The maximum number of events (335) was recorded on 12 August. Scientists found that the temperature of the southern crater wall remained high (307 ºC on 14 August) as it has since April 2002. There were no changes in water-pool temperature in the crater, nor had changes occurred in water level, sediment content, or fumarolic activity in the crater. The last time over 300 isolated volcanic-tremor events per day had been recorded at Aso was during 19 June-2 July 1992.
Source: Japan Meteorological Agency (JMA) via the Volcano Research Center
Hachijojima
| Japan
| 33.137°N, 139.766°E
| Elevation 854 m
JMA reported that seismicity increased at Hachijo-jima beginning on 13 August around 1600. By 1700 that day 16 earthquakes were felt, with a maximum magnitude of 3. The hypocenters were located ~2 km off of the island's W shore at depths of 5-15 km, depending on assumed seismic-wave velocity models. During the afternoon of the 15th, the earthquakes migrated to the N, without a clear change in depth. By the 16th, volcanic tremor-like waveforms were also recorded. By the evening of the 16th seismicity began to decrease. JMA stated that the overall increase in seismicity might not lead directly to an eruption, though seismicity may continue at a similar level. According to the Geographical Survey Institute, GPS measurements revealed in the center of the island there was 5-6 cm of movement to the E and 10 cm of uplift until about 1500.
Source: Japan Meteorological Agency (JMA) via the Volcano Research Center
Izu-Torishima
| Japan
| 30.484°N, 140.303°E
| Elevation 394 m
The eruption that began at Tori-shima on 11 August continued until at least noon on the 14th. Eruption clouds reached ~1.2 km a.s.l. on the 13th and ~1 km a.s.l. on the 14th. During observations on the 14th, scientists found smoke was being emitted from three areas on the western inner wall of the summit crater. They also found that the crater seemed to have widened during the eruption and the sea surface was no longer discolored.
Source: Japan Meteorological Agency (JMA) via the Volcano Research Center
Suwanosejima
| Ryukyu Islands (Japan)
| 29.638°N, 129.714°E
| Elevation 796 m
Small explosive eruptions occurred at Suwanose-jima on 19 August. JMA reported that on the 19th two periods of continuous acoustic signals were recorded for 20-30 minutes each beginning around 0000 and 0630. The signals were the largest recorded thus far this year. Explosions and rumbling were heard from Toshima village, and an ash plume drifted to the SW. Volcanic tremor with continuous large acoustic signals was also recorded later in the day during 0940-0950 and 1410-1500. Small tremor events also occurred, and ash rose above the summit to an unknown height and drifted SE.
Sources: Japan Meteorological Agency (JMA) via the Volcano Research Center, Kyodo News, Associated Press
Witori
| New Britain (Papua New Guinea)
| 5.576°S, 150.516°E
| Elevation 724 m
The Darwin VAAC reported that at Pago on 14 August around 1030 a very thin, low-level ash plume was visible on satellite imagery. The plume extended N to NNW and was probably below ~2.1 km a.s.l. On the 16th, intermittent eruptions with low ash content produced low-level plumes. The Rabaul Volcano Observatory reported that the low level of activity was expected to continue.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
Ongoing Activity
Etna
| Sicily (Italy)
| 37.748°N, 14.999°E
| Elevation 3295 m
The Toulouse VAAC reported that beginning on 18 August around 1030, a web camera revealed that ash was near Etna's summit. Ash was also visible on satellite imagery. The Etna Volcan Sicilian website reported that during a visit to Etna on 18 August, ash was emitted from Northeast Crater, and gas, ash, and blocks were emitted from Bocca Nuova crater. Only gas was emitted from Voragine and Southeast craters.
Sources: Toulouse Volcanic Ash Advisory Centre (VAAC), Etna Volcan Sicilien (Charles Rivière)
Fuego
| Guatemala
| 14.473°N, 90.88°W
| Elevation 3763 m
A new cycle of eruptive activity began at Fuego on 16 July that consisted of an increase in Strombolian explosions and the occurrence of high-frequency volcanic tremor for 24 hours. On 28 July a thick gray ash cloud extended 10-15 km in length and drifted to the W. Ash was deposited in the areas of Rochela, Panimaché, Morelia, Santa SofÃa, Yepocà pa, and Chimaltenango. This activity was associated with the collapse of the front of a lava flow, which began on 23 January. On 29 July an increase in seismic activity was recorded, the energy of explosions in the crater increased, and there was a 2- to 3-km-long lava flow. On 2 August explosions changed from Strombolian to Vulcanian, ash columns rose 800-1,400 m above the crater, and avalanches of volcanic blocks traveled down the volcano's flanks. The same day, gas emission from the crater decreased significantly, and the SE lava flow did not travel as quickly as it had previously.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)
Kilauea
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 14-19 August, lava flows from Kilauea sporadically entered the sea, traveling to the coast through lava tubes and also on the land surface. On the morning of the 18th several people saw part of a lava bench collapse into the sea. For most of the report period seismicity was at normal levels, with a decrease in the amount of long-period earthquakes and tremor that had been occurring since early June. On the morning of the 18th the amount of long-period seismicity increased. No significant deformation was recorded at the volcano.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
Nyamuragira
| DR Congo
| 1.408°S, 29.2°E
| Elevation 3058 m
Scientists observing Nyamuragira, following the eruption that began on 25 July, found that on 6 August the lower part of a fracture on the volcano's N flank was active. They saw three very active lava fountains eject scoria about 100 m high and a very fast moving lava flow travel to the NE from a breach in the lowest part of the fracture. They estimated that about 3 million cubic meters of lava was being emitted per day. By the 7th, activity had dropped significantly, with only one weak lava fountain active and a decrease in the amount of tremor recorded.
Sources: Observatoire Volcanologique de Goma (OVG), UN Office for the Coordination of Humanitarian Affairs (OCHA)
Santa Maria
| Guatemala
| 14.757°N, 91.552°W
| Elevation 3745 m
Based on information from INSIVUMEH, the Washington VAAC reported that a lava-dome collapse at Santa MarÃa on 16 August at 0919 produced ash that rose to near the summit. No ash was visible on satellite imagery.
Source: Washington Volcanic Ash Advisory Center (VAAC)
Sheveluch
| Central Kamchatka (Russia)
| 56.653°N, 161.36°E
| Elevation 3283 m
During 9-16 August, seismicity remained above background levels at Shiveluch with about 10 earthquakes occurring with magnitudes 1.7-2.4 and a number of smaller earthquakes at depths of 0-6 km. In addition, many other local shallow seismic signals were registered, which possibly indicated ash-and-gas explosions (one to three per day to heights of 1.5-2.5 km above the dome). Avalanches were also registered. Seismicity decreased slightly by the end of the week. On several days thermal anomalies were visible on satellite imagery. The Concern Color Code was reduced from Orange ("explosive eruption is possible within a few days and may occur with little or no warning") to Yellow ("volcano is restless").
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
Soufriere Hills
| Montserrat
| 16.72°N, 62.18°W
| Elevation 915 m
Volcanic and seismic activity at Soufrière Hills remained at high levels during 9-16 August. Lava-dome growth remained focused on the N side of the dome complex. Rockfall talus accumulated in the upper portions of Tuitt's Ghaut, and small pyroclastic flows occurred to the N in both Tuitt's and White's ghauts. The active lobe also shed rockfall talus into the notch in the north-western sector of the old dome which leads towards Tyre's Ghaut. SO2 fluxes remained at moderate levels.
Source: Montserrat Volcano Observatory (MVO)
Tungurahua
| Ecuador
| 1.467°S, 78.442°W
| Elevation 5023 m
During 14-20 August, emissions of steam, gas, and ash continued at Tungurahua. According to pilot reports, ash was seen rising to a maximum height of ~9.1 km a.s.l. Ash was not visible on satellite imagery.
Source: Washington Volcanic Ash Advisory Center (VAAC)
Criteria & Disclaimers
Criteria
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.
Disclaimers
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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