Wed, 25 Jul 2001, 06:00
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.
Wed, 25 Jul 2001, 06:00After 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.
Wed, 25 Jul 2001, 06:00
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.
Wed, 25 Jul 2001, 06:00KVERT 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.
Wed, 25 Jul 2001, 06:00
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.
Wed, 25 Jul 2001, 06:00Several 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.
Wed, 25 Jul 2001, 06:00
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.
Wed, 25 Jul 2001, 06:00Continuous 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.
Wed, 18 Jul 2001, 06:00
During the week heavy rain remobilized ash deposited on the flanks of the volcano, generating lahars, and several small-to-moderate eruptions produced ash clouds. On 19 July lahars that traveled down the W flank of the volcano reached the Baños-Riobamba highway. The Washington VAAC reported that one of the larger eruptions during the week occurred on 20 July at 2104 and produced an ash cloud that rose to ~7.9 km a.s.l.
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Wed, 18 Jul 2001, 06:00A moderate-sized eruption at Shiveluch on 19 July prompted KVERT to raise the Concern Color Code from Yellow to Orange the same day. The eruption occurred at 1033 and produced an ash plume that rose 3 km above the lava dome. Prior to the eruption, during 14 through 16 July, spasmodic volcanic tremor increased several times.
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Wed, 18 Jul 2001, 06:00
A large flank eruption began on 17 July at Etna and produced several lava flows that were emitted from four new fissures and strong explosive activity at a fifth. Four of the fissures were on the SE flank, and the fifth was on the NE flank. There were fears that lava flows from two of the fissures would reach the town of Nicolosi (~15 km SSE of the volcano) and a nearby popular tourist area.
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Wed, 18 Jul 2001, 06:00The number of rockfalls increased (719) during 13-20 July in comparison to the previous week (297), although most of them were very small. Near-continuous rockfalls occurred on the S side of the lava dome, where dome growth was concentrated. Numerous pyroclastic flows originated from the S flank of the dome and moved eastward down the Tar River Valley.
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Wed, 18 Jul 2001, 06:00
Seismic data revealed that during 9-15 July activity was higher than in the previous week. During this period 687 explosion events were recorded, as well as 57 avalanches, and 11 tectonic earthquakes. The volcano remained at Alert Level 2 (on a scale of 1-4).
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Wed, 18 Jul 2001, 06:00Several small-to-moderate sized emissions occurred at Popocatépetl that were mainly composed of steam, gas, and small amounts of ash.
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Wed, 18 Jul 2001, 06:00
During 9-15 July volcanic activity at Merapi was similar to the previous week. A total of 52 lava avalanches traveled SW to a maximum distance of 2.5 km down the Sat, Senowo, and Lamat rivers. Emissions from low-pressure fumaroles rose to 755 m above the summit.
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Wed, 18 Jul 2001, 06:00Volcanic activity at Mayon was similar to the previous week. During 17-23 July seismicity consisted of four high-frequency and 37 low-frequency earthquakes, and 203 high-frequency short-duration harmonic tremors. An average of 4,100 metric tons per day of SO2 was emitted from the volcano, which was still above the baseline value of 500 metric tons per day.
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Wed, 18 Jul 2001, 06:00
There were 728 shallow volcanic earthquakes at Krakatau during 9-15 July, which was a significant increase in comparison to the previous week. No visual observations were made. The volcano remained at Alert Level 2 (on a scale of 1-4).
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Wed, 18 Jul 2001, 06:00During the week lava entered the sea at a moderate rate at the E Kupapa`u entry. On 18 July at 1803 a M 3.5 earthquake rattled though the lower east rift zone of Kilauea. Surface flows were vigorous in two areas of the current lava flow field; one in the E branch of the flow field at the base of the Pulama pali scarp, and the other just SE of the shatter ring in the W branch of the flow field.
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Wed, 18 Jul 2001, 06:00
During 9-15 July volcanic activity was at a level similar to the previous week. Seismicity was dominated by 572 small explosions, 451 multiphase earthquakes, and continuous lava avalanches. The avalanches traveled up to 2.5 km down the Keting River and lava flowed as far as 750 m down the Kahetang River.
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Wed, 11 Jul 2001, 06:00A news report on 9 July stated that residents who were evacuated from their homes near Ulawun were permitted to return home. They were evacuated in May after the occurrence of relatively high seismic activity and an eruption in April. On 14 June, almost a month before the news report was published, the Rabaul Volcano Observatory (RVO) recommended that the Alert Level be reduced to 1.
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Wed, 11 Jul 2001, 06:00
After eruptions occurred on 25 and 29 June, volcanic activity continued at high levels at Karangetang. During 30 June to 8 July seismographs recorded signals that represented small explosions, avalanches, and an average of 33 multiphase earthquakes per day. During this period a gray plume was emitted from the volcano, and lava avalanches traveled as far as 2.5 km down the Keting River and 750 m down the Kahetang River.
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Wed, 11 Jul 2001, 06:00During the week several small-to-moderate eruptions produced ash clouds. The largest eruption, on 12 July, produced an ash cloud that rose to ~8.3 km a.s.l. and drifted W to NW.
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Wed, 11 Jul 2001, 06:00
During 6 to 13 July volcanic activity at Soufrière Hills remained similar to the previous week. Lava dome growth appeared to still be concentrated on the S side of the dome where near-continuous rockfalls occurred. According to the Washington VAAC, the rockfalls produced ash plumes that did not rise above 3 km a.s.l. and drifted to the W or WNW.
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Wed, 11 Jul 2001, 06:00Seismic activity remained above background levels during 6-13 July. Many small earthquakes were recorded within the volcano's edifice, along with weak spasmodic tremor and other local seismic signals, interpreted as related to explosions, avalanches, and collapses. On 6 July explosions sent ash to .6-1 km above the volcano.
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Wed, 11 Jul 2001, 06:00
Seismic data revealed that during 2-8 July the number of explosions and avalanche earthquakes at Semeru decreased in comparison to the previous week. The volcano was at Alert Level 2.
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Wed, 11 Jul 2001, 06:00Several small-to-moderate sized emissions occurred at Popocatépetl, including three on 14 July. According to the Washington VAAC, around 1045 an emission of steam, gas, and small amounts of ash rose to ~7.3 km a.s.l. and drifted to the W.
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Wed, 11 Jul 2001, 06:00
During 2-8 July low-pressure emissions from fumaroles rose 700 m above the volcano. During the same interval lava avalanches traveled SW to a maximum distance of 2.5 km into the upper reaches of the Sat, Senowo, and Lamat rivers. The volcano was at Alert Level 2.
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Wed, 11 Jul 2001, 06:00Volcanic activity continued to decrease at Mayon during 8-16 July, with low seismicity, occasional SE-directed rockfalls, and a general decrease in SO2 emission rates. Although the volcano's edifice remained slightly inflated, a gradual deflationary trend was detected. The activity decrease led PHIVOLCS to reduce the Alert level from 4 (hazardous eruption imminent) to 3 (increased tendency towards eruption).
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