During 28-29 September seismic activity was above background levels and weak, shallow seismic signals (possible collapses and avalanches) were registered. Several small explosions occurred on 30 September, sending ash clouds to the following heights above the dome: 2.5 km at 1323, 3.5 km at 1719, 2.5 km at 1755, and 4.5 km at 1807. An explosion at 2010 produced an umbrella-shaped ash cloud that rose 9 km above the lava dome and extended ~9 km E to W. Large pyroclastic flows traveled ~5 km to the SE. The same day the Concern Color Code was raised from Orange to Red. During 28-30 September thermal anomalies in the active dome area were visible on satellite imagery. Following the eruption, during 30 September at 2100 to 1 October at 0900, seismic activity decreased and the view of the volcano was obscured by clouds. AVHRR satellite imagery at 0757 showed that the ~25-km-diameter ash cloud remained centered over the volcano. On 1 October the Concern Color Code was reduced back to Orange.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Anchorage Volcanic Ash Advisory Center (VAAC), Tokyo Volcanic Ash Advisory Center (VAAC), China Daily.com

During 24-30 September volcanic activity increased at Talang volcano. Observers noted that on 25 September during 1722-1838 a thick white-brownish plume with high gas pressure rose 200-350 m above the volcano. Personnel at the observatory could smell sulfur during the evening. In comparison to measurements in 2000, temperatures increased in 2001 at Batu Bajanjang hot spring (from 40-60°C to 45-66°C), Gabuo Atas fumarole field (from 98-99°C to 111-114°C), and Gabuo Bawah fumarole field (from 96-99°C to 100-101°C). In addition, the water level at Batu Bajanjang hot spring decreased drastically. Talang was at Alert Level 2 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

According to reports on 28 September, gas emissions from Bocca Nuova crater had been vigorous at times during the previous few weeks. In addition, a dense gas plume was visible rising above Northeast Crater. The cones that formed during the July-August 2001 eruption on the S flank continued to emit heat and minor amounts of gas.

Source: Italy's Volcanoes

During 17-23 September lava flows and lava avalanches rarely occurred at Karangetang. Small white-colored emissions rose ~500 m above the main crater and 50-200 m above Crater II. A 10- to 100-m-high "red reflection" was visible above the volcano. Seismic activity decreased in comparison to the previous week and was dominated by multiphase and avalanche earthquakes. During 24-30 September seismic activity continued to decrease and few lava avalanches were observed emanating from main crater. Plumes rose 400 m above the summit of the main crater and 50-100 m above Crater II. A 25-m-high "red reflection" was observed. The Alert Level remained at 3 (on a scale of 1-4).

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

Kavachi erupted daily during August through mid-September. During August ash and volcanic projectiles were observed rising 400 m above sea level and the glow from the volcano was visible from the coast of Gatokae Island, 32 km away.

Source: The Wilderness Lodge

Lava flows from the W of the active flow field began to enter the ocean at a new area during the evening of 28-29 September. The ocean entry was located S of the former site of Komoamoa camping area. By 30 September a new lava bench and an adjacent black sand beach had begun to form. Lava continued to flow into the ocean at the E Kupapaʻu entry, although the overall size of the entry had diminished. Surface lava flows were visible above and on the Pūlama pali scarp. The lava flows W and E of the flow field that had been active for the past couple of weeks had mostly crusted over. Generally, volcanic tremor remained at moderate-to-low levels at Kīlauea's summit and Puʻu ʻŌʻō. Background tremor at Puʻu ʻŌʻō was interrupted at intervals of ten's of minutes to an hour or two, by short-lived bursts of relatively vigorous tremor. Tiltmeters across the volcano showed no significant deformation.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

Volcanic activity at Manam during September was very low. Occasional emissions of weak-to-moderate volumes of thin white vapor were visible at Main Crater. Southern Crater emitted very small volumes of thin white vapor.

Source: Rabaul Volcano Observatory (RVO)

During 17-30 September incandescent lava avalanches traveled SW primarily down the Lamat, Senowo, and Bebeng rivers to a maximum run-out distance of 2.5 km. During 17-23 September 51 lava avalanches were observed. Temperatures at Gendol Crater increased from 590-595 ºC the previous week to 602-617 ºC during 17-23 September and to 598-618 ºC during 24-30 September. Avalanche earthquakes, which dominated the seismicity, increased in comparison to the previous week.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

During the week, volcanic activity at Popocatépetl consisted of small emissions of steam, gas, and minor amounts of ash, and episodes of harmonic tremor. Pilots reported that a steam emission rose 4 km above the volcano on 26 September at 1000.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

During 10-30 September summit activity at Tavurvur, a stratovolcano of the Rabaul Caldera, was very low. During the report period very small-to-moderate amounts of steam were emitted from the active vent and low-frequency volcanic earthquakes decreased. After the 11th seismic activity was relatively low, except for a slight increase on the 16th. Very slow deflation began on 20 September.

Source: Rabaul Volcano Observatory (RVO)

According to the Darwin VAAC, a pilot reported observing an ash plume rising 1-4 km above Semeru on 1 October at 1457. No ash was visible in satellite imagery, possibly due to low-level meteorological clouds obscuring the plume.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Volcanic activity at Soufrière Hills during 21-28 September was similar to the previous week, except for a slight reduction in the number of hybrid earthquakes. Seismicity continued to be dominated by bands of hybrid earthquake swarms and increased rockfall activity with periodicities of approximately 11 to 13 hours. The active lava dome continued to grow at a moderate rate, producing rockfalls and small but energetic pyroclastic flows that traveled E to the upper reaches of the Tar River Valley. Periods of vigorous ash venting were associated with the hybrid-earthquake swarms. Steam-and-ash clouds were visible on satellite imagery rising to ~500 m above the volcano.

Sources: Washington Volcanic Ash Advisory Center (VAAC), Montserrat Volcano Observatory (MVO)

On 24 September at 1500 an eruption at Tungurahua produced an ash cloud that rose ~2 km above the volcano and drifted to the W and SW. Roaring and the sound of rockfalls were heard in several towns near the volcano. An eruption on 25 September at 1230 produced a mushroom-shaped ash cloud that rose 5 km above the volcano. The lower portion of the plume drifted to the NW, while the higher portion remained fixed. Ash fell in the town of Cotaló. During the evening of the 25th Strombolian activity was observed, with rockfalls and incandescent volcanic fragments travelling to the W and NW flanks of the volcano. After the eruption volcanic activity consisted of low-level emissions of steam, gas, and ash. Small amounts of ash fell in southern Quero.

Sources: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN), Washington Volcanic Ash Advisory Center (VAAC)

Volcanic tremor occurred at Ulawun on 24 September at 2200 through 30 September. After the tremor peaked on the 27th at about 1000 it fluctuated as it generally declined. By 30 September seismic activity was at moderate levels. During 27-30 September a very slow deflationary trend was detected.

Source: Rabaul Volcano Observatory (RVO)