Activity for the week of 23 July-29 July 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
| Central Kamchatka (Russia)
| 55.972°N, 160.595°E
| Elevation 2882 m
A large explosion at Bezymianny on 26 July at 2220 produced an ash plume that rose to a height of ~8 km a.s.l. and drifted W. KVERT raised the Concern Color Code from Green to Red, the highest level. Prior to the eruption, a weak thermal anomaly was detected on satellite imagery on 6 July, and two shallow low-magnitude earthquakes were recorded on 23 and 25 July. On the 25th and 26th a several-pixel-large thermal anomaly and a gas-and-ash plume were seen on satellite imagery. On the 26th the active phase of the eruption lasted for ~4 hours. According to Yelizovo Airport Meteorological Center (AMC) and a pilot's report, by 26 July at 2226 the ash cloud was around 10-11 km a.s.l. On 27 July an ash cloud was visible 250-300 km W of the volcano and probable pyroclastic-flow deposits were seen on the volcano's SE flank. The same day the Concern Color Code was reduced from Red to Orange. No seismicity was recorded during 27-28 July and no visual information was available because Bezymianny was obscured by clouds. No new signs of eruptive activity were visible on satellite imagery after 26 July. On 29 July the Concern Color Code was further reduced from Orange to Yellow.
Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC), Pravda News
| Kyushu (Japan)
| 32.884°N, 131.104°E
| Elevation 1592 m
During 12-14 July, JMA recorded seismic signals at Aso that were associated with five small phreatic eruptions. Around 1400 on 27 July continuous volcanic tremor started. Such activity had not been recorded at Aso since November 1995. As of 28 July ~10 earthquakes occurred per day, and around 100 isolated tremor events had occurred since 23 July. On the 28th the crater lake in Crater 1 was gray, 76 °C, and bubbling in the center.
Source: Japan Meteorological Agency (JMA)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During 23-28 July at Kilauea, surface lava flows were visible on the coastal flat and upslope on the Pulama pali. No lava flowed into the sea. 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 during the report week.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| Central Kamchatka (Russia)
| 56.056°N, 160.642°E
| Elevation 4754 m
Seismicity was above background levels at Kliuchevskoi, with 6-17 M 1.8-2.4 earthquakes occurring each day at depths of ~30 km and at shallower levels. Gas-and-steam plumes rose to a maximum height of ~1 km above the crater. Kliuchevskoi remained at Concern Color Code Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Flores Island (Indonesia)
| 8.365°S, 122.833°E
| Elevation 1095 m
Based on an aircraft report, the Darwin VAAC reported that an eruption from Leroboleng on 29 July at 0900 lasted 10 minutes and produced an ash cloud to a height of ~7.3 km a.s.l.
Source: Darwin Volcanic Ash Advisory Centre (VAAC)
| 19.023°N, 98.622°W
| Elevation 5393 m
During 23-29 July, moderate emissions of mainly gas, steam, and sometimes ash occurred at Popocatépetl. Aerial photography taken on 21 July revealed than an external lava dome was not visible at the bottom of the crater. A significant explosion occurred on 25 July at 2053, throwing incandescent fragments on Popocatépetl's slopes. According to news reports, the loud explosion panicked some residents in nearby communities.
Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Associated Press
| 14.757°N, 91.552°W
| Elevation 3745 m
Based on information from INSIVUMEH, the Washington VAAC reported the occurrence of small eruptions at Santa María around 22 July, one of which produced an ash column to ~4.5 km a.s.l. Satellite imagery indicated that the plume from an eruption on 23 July around 0730 drifted W.
Source: Washington Volcanic Ash Advisory Center (VAAC)
| 16.72°N, 62.18°W
| Elevation 915 m
During 18-25 July, volcanic and seismic activity at Soufrière Hills were at very low levels, with only a few events triggering the seismic network. The pattern of earthquakes during the week indicated that lava-dome growth within the explosion crater had probably restarted, although this could not be confirmed because Soufrière Hills was obscured by low-level meteorological clouds. Sulfur-dioxide flux declined somewhat in comparison to the previous week.
Source: Montserrat Volcano Observatory (MVO)
| Aeolian Islands (Italy)
| 38.789°N, 15.213°E
| Elevation 924 m
According to INGV-CT, the eruption that began at Stromboli on 28 December 2002 ended on 22 July. Strombolian activity occurred almost continuously in July, with spatter often falling outside the rim of Crater 1 (the NE crater). Mainly degassing and sporadic ash emissions occurred at Crater 3 (the SW crater), with Strombolian explosions becoming more common during the second half of July. Erosion of the N flank of Crater 1 by landslides in the upper Sciara del Fuoco increased in July, with the 30 December 2002 landslide scar extending backward and upslope, cutting the flank of the cone just 50 m below the crater rim. Lava effusion from vents located at about 600 m elevation on the upper eastern corner of the Sciara del Fuoco decreased beginning in early June, completely stopping between 21 and 22 July.
Source: Sezione di Catania - Osservatorio Etneo (INGV)
News Feeds and Google Placemarks
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A Google Earth network link for the Weekly Volcanic Activity Report can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano profile page and to the complete Weekly Report for that week. This feature was first made available on 1 April 2009.
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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