Activity for the week of 25 July-31 July 2001
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
KVERT raised the Concern Color Code from Green to Orange on 27 July after seismic and satellite data revealed that an extrusive process began at Bezymianny's lava dome. On 23 and 24 July gas-and-steam plumes rose 200-700 m above the dome. On 25 July seismic activity at the volcano increased above background levels as shallow earthquakes and weak, long local seismic events (possible collapses and/or avalanches) were recorded. On 26 July a linear three-pixel thermal anomaly was visible on satellite imagery trending SE from the summit. The Concern Color Code was reduced to Yellow on 31 July because seismic activity was at background levels during 28-31 July and only weak fumarolic activity was observed.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| Sicily (Italy)
| 37.748°N, 14.999°E
| Elevation 3295 m
During 25-31 July the eruption that began on 17 July at Etna's Southeast Crater continued at the same five eruptive fissures as the previous week. One of the fissures was located on the NE flank and the other four on the S flank at elevations of 2,950, 2,700, 2,500, and 2,100 m. During 24-26 July eruptive activity declined at the 2,100 m fissure, but then intensified on 27 July to reach the original level of Strombolian activity on the evening of 28 July. On 26 July modest lava emission occurred at the NE-flank fissure. At the 2,500 m fissure, where the strongest explosive activity occurred, a change was noted from the mostly phreatomagmatic eruptions that were prominent during the previous week to more violent Strombolian explosions and lava effusion. After lava began to flow from the 2,500 m fissure on 25 July, a pyroclastic cone began to grow around three of the vents and by 30 July the cone was ~100 m high. At the 2,950 m fissure (near the base of Southeast Crater) and 2,700 m fissure lava emission and mild explosive activity continued.
On 26 July lava from the 2,500 m elevation fissure continued to flow towards Rifugio Sapienza tourist complex, and as of 31 July a cable car base station and a small tourist shop had been destroyed by lava that surpassed constructed earth barriers. Lava continued to flow from the lower vents of the 2,100 m fissure in the direction of the town of Nicolosi (~15 km SSE of the volcano), but it was no longer considered a significant threat to the town. Near-continuous ashfall occurred S of the volcano, including in the town of Catania, ~25 km SSE of the volcano. The international Fontanarossa airport in Catania was closed repeatedly on 29 and 30 July due to ash on the runways. The Toulouse VAAC reported that ash clouds were occasionally visible on the Sistema Poseidon web cam and satellite imagery, with the highest cloud rising ~5.5 km above the volcano.
Sources: Italy's Volcanoes, Etna Volcan Sicilien (Charles Rivière), Toulouse Volcanic Ash Advisory Centre (VAAC), Reuters, Associated Press
| Luzon (Philippines)
| 13.257°N, 123.685°E
| Elevation 2462 m
After the pyroclastic-flow producing eruptions on 26 July Mayon entered an effusive eruptive phase. During 27-31 July lava flowed up to 3.75 km toward the SE in the Bonga Gully, accompanied by numerous high-frequency short-duration tremor events caused by rock fragments detaching from the newly deposited lava flow. Incandescence was visible at the crater, and thick steam plumes and occasional short-lived ash emissions were seen. SO2 emission rates were high, with a maximum of 9,900 metric tons measured on 31 July, which was well above the baseline value of 500 metric tons/day. Due to the possibility of further explosions, Alert Level 5 (the highest level) remained in effect. According to news reports, on 31 July officials allowed residents who live outside of the 7-km danger zone to return to their homes.
Sources: Philippine Institute of Volcanology and Seismology (PHIVOLCS), Associated Press, Reuters
| Central Kamchatka (Russia)
| 56.653°N, 161.36°E
| Elevation 3283 m
During the week seismic activity remained above background levels, with many small earthquakes occurring within the volcano's edifice and many different seismic signals (explosion, avalanche, collapse) recorded locally. Gas-and-steam plumes were observed from Klyuchi town and the highest cloud rose to 2 km above the lava dome. One- to three-pixel anomalies were occasionally visible on AVHRR imagery near the SW flank of the volcano. The volcano remained at Concern Color Code Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)
| 16.72°N, 62.18°W
| Elevation 915 m
On 29 July ash from Soufrière Hills drifted W, leaving deposits as far away as San Juan, Puerto Rico, 450 km to the WNW. The Washington VAAC issued an advisory on 27 July stating that a steady stream of ash was emitted from the volcano through the evening, rising to 800 m. There was also a persistent, strong hot spot over the volcano's summit visible in satellite imagery. According to MVO, the amount of ash emitted from the volcano increased during 27 July through 29 July, and seismic activity rose on 29 July. Beginning at 1500 on 29 July heavy rainfall mixed with ash deposits and generated lahars that flowed NW down the Belham River. The lava dome that had been growing in the summit region of the volcano during recent years partially collapsed, generating pyroclastic flows that traveled down the E flank of the volcano and entered the sea. Shortly after 1700 observers reported seeing pyroclastic flows and a continuous dense plume of ash that drifted to the W. Dense meteorological clouds, associated with a tropical wave, crossed the island and prohibited ash cloud detection in satellite imagery or ground confirmation of the height of the ash cloud. MVO reported that the large amount of ash that was being vented from the volcano rose to below 6 km. By midnight seismic and pyroclastic flow activity returned to low levels. The next day AVHRR imagery showed possible ash in an area W of Montserrat and SE of Puerto Rico. The position of the cloud correlated with ground observations of ash and haze from Christiansted, St. Croix.
There were reports of substantial ashfall and sporadic falling of "stones" in the Montserrat residential areas of Salem and Olveston in the N part of the island. Ash also fell in the US and British Virgin Islands, Roosevelt Roads (Puerto Rico), Christiansted (St. Croix), and as far as 450 km away from the volcano in San Juan (Puerto Rico). The ashfall in San Juan and the surrounding area led to the closing of the San Juan International Airport on 30 July. The airport reopened the next day.
Sources: Montserrat Volcano Observatory (MVO), Washington Volcanic Ash Advisory Center (VAAC), Associated Press, Reuters
| 30.793°N, 130.305°E
| Elevation 704 m
Continuous volcanic tremor was recorded at Satsuma-Iwo-jima during 20 to at least 23 July. A seismometer about 700 m SW of Iwo-dake crater recorded 50-100 earthquakes daily, in comparison to 30-90 earthquakes recorded daily during December 2000 and March 2001. Small amounts of volcanic tremor were also occasionally recorded. The Iwo-jima Branch of the Mishima Village Office reported that ash fell during 19-21 July. Faint ashfall and small volcanic tremor had occurred since December 2000.
Source: Volcano Research Center-Earthquake Research Institute (University of Tokyo)
| Hawaiian Islands (USA)
| 19.421°N, 155.287°W
| Elevation 1222 m
During the week small-to-moderate levels of lava entered the ocean at the E Kupapa`u entry. During 26-28 July a stream of `a`a lava continuously advanced down the Pulama pali scarp to the coastal flat on the E side of the current lava flow field. Generally, weak, rather steady tremor and a few related long-period earthquakes continued beneath Kilauea's caldera. Near Pu`u `O`o the tremor also became weak and continuous. Elsewhere, seismicity was at normal levels. Tiltmeters across the volcano indicated no significant deformation.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)
| 19.023°N, 98.622°W
| Elevation 5393 m
Several small-to-moderate sized emissions occurred at Popocatépetl that were mainly composed of steam, gas, and small amounts of ash. The Washington VAAC received a pilot report on 24 July at 1100 of an ash cloud ~5.5 km above the volcano drifting to the W. On 23 July CENAPRED reduced the Alert Level from Yellow Phase III to Phase II because volcanic activity was at lower levels than it was in December 2000 when the Alert Level was originally raised.
Sources: Centro Nacional de Prevencion de Desastres (CENAPRED), Washington Volcanic Ash Advisory Center (VAAC)
| Ryukyu Islands (Japan)
| 29.638°N, 129.714°E
| Elevation 796 m
Volcanic tremor was detected near Suwanose-jima's Otake crater beginning on 25 July at 2200 until at least 26 July. JMA reported that an eruption on 26 July at 1430 produced a volcanic plume that rose to 1.3 km above the crater and drifted to the S. That day seismometers ~2 km SW of the crater recorded explosions at 0501, 0558, 0935, and 1055. According to the Suwanose-jima Branch of the Toshima Village Office, ash fell the morning of 26 July.
Source: Volcano Research Center-Earthquake Research Institute (University of Tokyo)
| 1.467°S, 78.442°W
| Elevation 5023 m
Several small-to-moderate eruptions occurred at Tungurahua during the week. The Washington VAAC reported that the highest ash cloud was produced from an eruption on 25 July at 0604. The ash cloud rose ~9 km a.s.l. and drifted to the SW.
Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG), Washington Volcanic Ash Advisory Center (VAAC)
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.
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An RSS (Really Simple Syndication) feed for the Weekly Volcanic Activity Report first made available on 5 March 2008 can be utilized with the aid of various free downloadable readers. The report content of the news feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website. On 12 March 2009, GeoRSS tags were added so that the latitude and longitude for each volcano could be included with the feed.
At the end of each individual report is a list of the sources used. We would like to emphasize that the World Organization of Volcano Observatories (WOVO) website (http://www.wovo.org/) lists the regional volcano observatories that have the most authoritative data for many of these events.
CAP (Common Alerting Protocol) feeds are XML files specifically formatted for disaster management.
Google Earth Placemarks
A Google Earth network link for the Weekly Volcanic Activity Report was first made available on 1 April 2009. This file 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 page for that volcano and to the complete Weekly Report for that week.