JMA reported 30 explosions during 31 August-7 September from Showa Crater at Aira Caldera’s Sakurajima volcano, some that ejected tephra as far as 1,300 m, and incandescence from the crater that was occasionally visible at night. The Alert Level remained at 3 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)

An eruption at Axial Seamount, inferred to have started at 2230 on 23 April with an earthquake swarm, was confirmed during 14-29 August by bathymetric data and observations made during a ROV Jason dive. Two large lava flows from the N rift zone (8-16 km N of the summit caldera) were at most 127 m thick; some of the thicker areas had drained collapse features indicating they had molten interiors when emplaced. The ROV traversed the flows for about 2 km. New, thinner lava flows were also identified in the NE summit caldera and on the NE rim.

Source: Oregon State University's Marine Science Center and NOAA/PMEL EOI Program

IG reported that during the morning on 2 September gas-and-steam plumes from Cotopaxi contained minor amounts of ash, rose 100 m above the crater, and drifted W and NW. At about 1318, plumes with moderate amounts of ash rose 4 km and drifted W. Ashfall was reported in Machachi, Aloasí, and Chaupi. Analysis of ash collected on 2 September showed that the greatest contribution of material was pre-existing and altered rock. On 3 September ash-and-water-vapor plumes rose 2.2 km and drifted N and NW. During an overflight scientists observed ash emissions that rose 1 km and drifted W then N; the plume continued to rise to 8.5 km as it drifted N. Several new cracks in the glaciers were noted, especially on the E and NE flanks. Blocks had been deposited on the N and S parts of the crater. The circular glacier at the top of the inside part of the crater had significantly decreased in size and had large fractures. Glacial melting on the upper flanks had also accelerated. Streams of meltwater were present on the N flank. Thermal images revealed temperature increases in the S and E parts of the crater and a significant increase in temperatures of emissions (200 degrees Celsius). Seismic amplitudes did not increase but signals 3-11 km deep aligned with the conduit suggested rising magma. Bright areas at the summit were observed at night, possibly from hot block deposits. During 4-8 September gas-and-ash plumes rose 1 km at most and drifted N and NW.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

Servicio Geológico Colombiano’s (SGC) Observatorio Vulcanológico and Sismológico de Manizales reported that during 1-7 September seismicity at Nevado del Ruiz was characterized by long-period earthquakes and short-duration volcanic tremor associated with gas-and-ash emissions. In addition, volcano-tectonic (VT) events occurred at depths between 0.4 and 6.4 km. The largest VT event was recorded at 0017 on 2 September, was a local M 1.4, and was 1.5 km NE of Arenas Crater at a depth of 3.8 km. Incandescence was recorded by a webcam installed near the volcano. Water-vapor-and-gas plumes rose 1.4 km above the crater and drifted NW, and were sometimes tinged gray due to the presence of ash. Ashfall was reported in Manizales (30 km NW) and Pereira (40 km WSW). The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").

Sources: Servicio Geológico Colombiano (SGC), La Patria

OVPDLF reported that scientists conducting fieldwork at Piton de la Fournaise during 31 August-1 September observed one active cone (20 m high) filled with a lava lake. Fluctuating lava fountains rose 15-20 m above the lake surface and gas bubbles exploded. Lava traveled through a 50-m-long lava channel and was a total of 1 km long. During 1-2 September seismicity increased, and the lava flow length increased to 2 km. Tremor remained high on 5 September. The lava lake was in two separate but side-by-side vents and lava fountains were lower compared to recent days. Five small lava flows were near the foot of the cone; four were 30 m long and the fifth was 1 km long. Tremor levels started to decline on 7 September but remained at a high level through 9 September.

Source: Observatoire Volcanologique du Piton de la Fournaise (OVPF)

JMA reported that on 3 September a small-scale eruption from Asosan’s Nakadake Crater generated a whitish plume that rose 200 m above the crater. During fieldwork later that day, scientists confirmed that the event originated in the SW part of the crater and minor ashfall had occurred. A white plume rose 400 m on 7 September. The Alert Level remained at 2 (on a scale of 1-5).

Source: Japan Meteorological Agency (JMA)

AVO reported that during 2-3 September a few very small earthquakes were detected at Cleveland. During 5-7 September elevated surface temperatures were detected in satellite images. Steaming from the summit was recorded by the webcam on 5 September. The next day satellite and webcam images showed a low-level gas-and-steam plume over the volcano. A robust steam plume was visible on 8 September. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Based on satellite images, the Washington VAAC reported that on 5 September a gas-and-ash plume from Colima rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted 60 km NW.

Source: Washington Volcanic Ash Advisory Center (VAAC)

Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that during 2-7 September ash plumes from Dukono rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 35-165 km W, NW, N, NE, E, and SE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

INSIVUMEH reported that during 1-2 September activity at Fuego was characterized by lava fountains, explosions, and ashfall in surrounding areas. Pyroclastic flows descended the flanks. An ash plume rose 1.3 km above the crater and drifted 15 km W. Ashfall was reported in San Pedro Yepocapa (8 km N) and Chimaltenango (21 km NNE), and in the communities of Panimaché (8 km SW), Morelia (9 km SW), Santa Sofía (12 km SW), and Sangre de Cristo (8 km WSW). Activity decreased by the afternoon of 2 September; remnants of three lava flows were visible in the Santa Teresa (S), Trinidad (S) and Las Lajas (SE) drainages. Weak explosions during 4-5 September generated ash plumes that rose 450 m and drifted 7 km W and SE.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Based on satellite images, information from PVMBG, and wind data, the Darwin VAAC reported that on 8 September an ash plume from Gamalama rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted over 25 km NE.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

KVERT reported that moderate explosive activity at Karymsky continued during 28 August-4 September. Satellite images detected a thermal anomaly on the volcano on 2 September. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

HVO reported that seismicity beneath Kīlauea's summit, upper East Rift Zone, and Southwest Rift Zone was at background levels during 2-8 September. The lava lake continued to circulate and spatter in the Overlook vent. The June 27th NE-trending lava flow continued to be active within 4-8 km NE of Puʻu ʻŌʻō Crater.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

Based on observations of satellite imagery and wind data analyses, the Darwin VAAC reported that on 7 September ash plumes from Manam rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 75 km NW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

INSIVUMEH reported that on 5 September an explosion from Santa María's Santiaguito lava-dome complex generated an ash plume that rose 700 m and drifted SW. Ashfall was reported in Monte Claro (S). On 8 September heavy rainfall triggered a hot lahar that descended the Nimá I river drainage on the S flank. The lahar carried tree trunks, branches, and 1-m-wide blocks, had a strong sulfur odor, and was 20 m wide and 1.5 m deep.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

KVERT reported that during 28 August-4 September lava-dome extrusion onto Sheveluch’s N flank was accompanied by fumarolic activity, dome incandescence, and hot avalanches. Satellite images detected an almost daily thermal anomaly over the dome. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

AVO reported that seismicity at Shishaldin continued to be elevated over background levels during 2-8 September, indicating that low-level eruptive activity confined to the summit crater continued. Cloud cover often prevented satellite and webcam observations; elevated surface temperatures were periodically detected in satellite images. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Based on information from PVMBG, the Darwin VAAC reported that on 2 September an ash plume from Sinabung rose 2 km above the summit. On 3 September an ash plume rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted over 35 km W. The next day an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 45 km W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

IG reported that on 1 September a lahar descended Tungurahua's flank, closing part of the Penipe-Riobamba road. On 2 September ash plumes rose 3 km and drifted W. The next day ashfall was reported in Quero (20 km NW), Santuario, El Rosario, La Galera, Choglontus (13 km WSW), El Manzano (8 km SW), and Pillate (8 km W).

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)

Instituto Geofísico del Perú (IGP) Observatorio Volcanológico del Sur (OVS) reported increased seismicity at Ubinas during 1-7 September, specifically an increase in the occurrence of long-period events and hybrid signals. Tremor increased during 5-7 September. A steam plume rose 1.5 km above the base of the crater on 2 September, and ash emissions were recorded during 6-7 September.

Source: Instituto Geofísico del Perú (IGP)