HVO reported on 30 September that a pattern of slow deflation occurring at Mauna Loa for the past 9 years abruptly changed in mid-May when the summit area began to slowly swell and stretch. Global Positioning System measurements revealed that distances across the summit caldera (Moku`aweoweo) have been lengthening at a rate of 5-6 cm per year, and the caldera has widened about 2 cm since 12 May. The summit area was slightly higher than before mid-May, consistent with swelling.
AVO reported that seismic unrest that began at Veniaminof on 10 September continued through the 27th. The intensity of tremor and small earthquakes under the volcano had decreased since the 10th, but remained above the background level established during the summer of 2002. Visual observations of Veniaminof were hampered by poor weather.
On 28 September around 0400 an eruption occurred at Ulawun that produced an ash-and-steam cloud to ~3.7 km a.s.l. The cloud was visible on satellite imagery at 0632 drifting WSW.
During 25 September-1 October, emissions of steam, gas, and ash continued at Tungurahua. Ash was seen rising to a maximum height of ~7 km a.s.l.
During 20-27 September, activity at Soufrière Hills'dome complex increased in comparison to the previous week, with a major change in direction of extrusion following a hybrid earthquake swarm the previous week. Growth of the previously active NE lobe stagnated during the 21st to 22nd. A near vertical spine was extruded in the central area around the 21st, possibly indicating a switch in growth direction.
During 20-27 September, volcanic and seismic activity at Shiveluch were above background levels. There were four earthquakes with magnitudes 2-2.1, and many smaller ones. Seismic data indicated possible avalanches and ash-and-gas explosions that may have sent material to 5.5 km a.s.l.
During 25-30 September at Kilauea, lava continued to travel SE down Paliuli and Pulama pali, and surface lava flows were visible on the coastal flat. Lava entered the sea at multiple points along the fronts of two lava deltas and visitors saw several sudden collapses of the front of the bench (land built out from the sea cliff). Generally, seismicity was at normal levels.
Pulses of low-frequency tremor were first recorded on 10 September by several seismic stations at Veniaminof. Until at least 20 September the overall level of seismicity decreased, but remained above background. AVO did not receive any reports of anomalous activity, and poor weather limited satellite observations.
Wed, 18 Sep 2002, 06:00
VSI increased the Alert Level at Ruang to 4 (the highest level) when the volcano began to erupt on 25 September at 0100. During the 7-hour eruption an ash cloud rose 0.5-1 km above the summit. Ruang erupted again at 1140, producing an ash cloud that VSI reported rose to 5 km above the summit.
Read allWed, 18 Sep 2002, 06:00
On 19 September at 0700 a low-level ash plume from Ulawun was visible on satellite imagery.
Read allWed, 18 Sep 2002, 06:00
During 7-13 September, emissions of steam, gas, and ash continued at Tungurahua. Ash was seen rising to a maximum height of ~7 km a.s.l.
Read allWed, 18 Sep 2002, 06:00
During 13-20 September, activity at Soufrière Hills increased in comparison to the previous week. Lava-dome growth was directed to the NE, with frequent rockfalls and small pyroclastic flows sending material to a sector extending from the central Tar Valley on the E flank to the NE flanks above Tuitt's Ghaut. Some material tumbled down a notch onto the northern flank.
Read allWed, 18 Sep 2002, 06:00
During 13-20 September, volcanic and seismic activity at Shiveluch were above background levels. There were eight earthquakes with magnitudes 2-2.3, and many smaller ones. Seismic data indicated possible avalanches and ash-and-gas explosions that may have sent material to 3 km above the lava dome.
Read allWed, 18 Sep 2002, 06:00
Ash clouds were observed at Semeru rising to ~7.6 a.s.l. on 22 September at 1453 and on 23 September at 1700. The September 23rd cloud drifted SW. Neither cloud was visible on satellite imagery due to meteorological clouds in the area.
Read allWed, 18 Sep 2002, 06:00
During 17-22 September, at Kilauea lava continued to travel SE down Paliuli and Pulama pali, and surface lava flows were visible on the coastal flat. Lava also continued to flow into the sea. Generally, seismicity was at normal levels.
Read allWed, 18 Sep 2002, 06:00
During 13-20 September, seismicity at Karymsky remained above background levels, with 200-300 local shallow events occurring per day. The character of the seismicity indicated that ash-and-gas explosions rose to ~1 km above the volcano and gas blow-outs possibly occurred. On 16 September at 1217 a short-lived explosion sent an ash-and-gas plume to a height of ~3 km a.s.l.
Read allWed, 18 Sep 2002, 06:00
The Asama Volcano Observatory reported that a period of high seismicity began at Asama on 18 September around 0620. Normally 30-59 earthquakes occur daily at the volcano, but on the 18th and 19th, they recorded 243 and 128 volcanic earthquakes, respectively. During this time, a relatively large amount of volcanic gas was emitted from the summit.
Read allWed, 11 Sep 2002, 06:00
On 12 September at 0700 a low-level ash plume located NNW to NNE of Ulawun was visible on satellite imagery. By 1132 the plume was no longer visible.
Read allWed, 11 Sep 2002, 06:00
On 10 September AVO detected 1-minute-long pulses of low-frequency tremor occurring every 2-5 minutes on several seismic stations at Veniaminof. This type of seismicity is indicative of volcanic unrest. Retrospective analysis of seismic data suggested that tremor began as early as 8 September.
Read allWed, 11 Sep 2002, 06:00
On 2 September VSI raised the Alert Level at Tangkubanparahu from 1 to 2 (on a scale of 1-4). The number of daily earthquakes had been increasing for 2 weeks and the temperatures of Domas and Ratu craters were 2-4°C higher than normal. There were no surface changes at the volcano, but several animals from the forest near Ratu crater were found dead in the crater.
Read allWed, 11 Sep 2002, 06:00
Activity at Tungurahua was very low during 9-12 September, with low gas emission (50 tons of SO2 on 12 September) and negligible seismic activity. On the 12th at 1300 a sudden ash emission occurred that marked the onset of a new eruptive phase. A dark ash column reached 1 km above the crater and drifted W.
Read allWed, 11 Sep 2002, 06:00
Activity at Suwanose-jima was relatively low from 26 August until 12 September. On the 12th explosive eruptions began to occur frequently. According to the Suwanose-jima office of Toshima village, rumbling was intermittently heard about 4 km SSW of the summit and small amounts of ash fell.
Read allWed, 11 Sep 2002, 06:00
During 6-13 September, activity at Soufrière Hills remained at moderate levels. Growth on the lava-dome complex remained centralized on the E flank, with frequent rockfalls and small pyroclastic flows. At the beginning of the week most of these spilled eastward along the N side of the Tar River Valley, but later in the week activity appeared to refocus northward onto Tuitt's Ghaut.
Read allWed, 11 Sep 2002, 06:00
During 6-13 September, volcanic and seismic activity at Shiveluch were above background levels. There were eight earthquakes with magnitudes 2-2.2, and many smaller ones. Seismic data indicated possible avalanches and ash-and-gas explosions that may have sent material to 3 km above the lava dome.
Read allWed, 11 Sep 2002, 06:00
On 8 September at 1947 an ash explosion at Semeru was accompanied by ejected incandescent material. The material traveled 150 m E to the upper portion of the Kembar River. During 2-8 September, seismicity was dominated by explosion earthquakes. Semeru remained at Alert Level 2 (on a scale of 1-4).
Read allWed, 11 Sep 2002, 06:00
During 11-16 September, lava continued to travel SE down Paliuli and Pulama pali, and many surface lava flows were visible on the coastal flat. Lava flowed onto the Wilipe`a bench directly seaward of the end of the Chain of Craters Road. Lava entered the sea at several points on the NE portion of the front of the bench.
Read allWed, 11 Sep 2002, 06:00
During 6-13 September, seismicity at Karymsky remained above background levels, with 200-250 local shallow events occurring per day. The character of the seismicity indicated that ash-and-gas explosions rose to ~1 km above the volcano and gas blow-outs possibly occurred. Observations of Karymsky on 8 September revealed three new small lava flows on the volcano's S and SE slopes.
Read allWed, 11 Sep 2002, 06:00
During 9-14 September, Strombolian activity continued at Etna's Northeast Crater, with ash and incandescent material being ejected from it. Volcanic bombs ejected vertically to heights of 100-150 m fell within the crater. Low-level ash clouds were visible on satellite imagery.
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