INETER reported that a seismic swarm near Apoyeque started at 1627 on 6 September in an area between the volcano and Managua (less than 10 km SW). At the time of the report, almost four hours after the start of the event, 17 earthquakes had been detected; three events were M 2.3-3.7, at depths ranging from 2.8 to 6 km. No earthquakes were recorded on 9 September.

Source: Instituto Nicaragüense de Estudios Territoriales (INETER)

Based on visual observations and analyses of satellite imagery, SVERT reported that during 4-10 September fumarolic activity at Grozny Group increased. The Aviation Color Code remained at Yellow.

Source: Sakhalin Volcanic Eruption Response Team (SVERT)

According to NASA's Earth Observatory, a satellite image of Krakatau acquired on 4 September showed fresh lava flows descending the SE flank of Anak Krakatau, extending the shoreline by about 100 m.

Source: NASA Earth Observatory

AVO reported that during 5-11 September seismic activity at Little Sitkin was much lower than the peak of activity during 29-30 August, but continued to remain elevated. Satellite views were obscured by clouds during 5 and 8-11 September. The Aviation Color Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

INETER reported that on 8 September three explosions from San Cristóbal produced ash-and-gas plumes that rose 1.5 km above the crater and drifted 9 km/hr NW. Ashfall was reported in El Viejo (18 km WSW), El Chonco, and Ranchería. Sporadic explosions later that day generated ash plumes that rose 1.5-5 km and drifted 50 km WNW. Ash fell in an area covering 2,438 square kilometers, including the communities of El Viejo, La Grecia, La Joya, Santa Catalina, El Piloto, Las Banderas, Las Rojas, Carlos Fonseca, Jiquilillo, Mechapa, and Cosiguina. Ashfall was 5 cm thick in areas near the crater and up to 3 mm thick in more distant places. Sulfur dioxide emissions were 3,221 tons per day, well above the normal range of 550 to 700 tons per day. A resident near the volcano reported landslides and falling rocks in the N part of the crater. Incandescent rocks fell in areas NW, causing burns on livestock. Residents in Versalles Arriba, near the crater, reported seeing a fissure. According to a news article, officials evacuated about 3,000 people. SINAPRED reported that airplanes were diverted around San Cristóbal to other airways.

Sources: Associated Press, Sistema Nacional para la Prevención, Mitigación y Atención de Desastres (SINAPRED), Instituto Nicaragüense de Estudios Territoriales (INETER)

MVO reported that during 31 August-7 September activity at the Soufrière Hills lava dome was at a low level, although seismicity remained slightly elevated. Clear views of parts of the dome showed very little change, apart from some modification to the steep eastern face from the formation of the pyroclastic flow on 29 August. The Hazard Level remained at 2 (on a scale of 1-5).

Source: Montserrat Volcano Observatory (MVO)

CVGHM reported that seismicity at Tangkubanparahu had increased significantly on 13 August, then again on 23 August; seismicity fluctuated and remained elevated through 6 September. Earthquakes were located 0.5-4 km beneath Ratu Crater and in an area W at depths of 4-12 km. Soil temperatures at Ratu Crater showed an increasing trend on 31 August, but had gradually declined by 5 September. Sulfur dioxide gas emissions were high in an area NW of the crater, causing CVGHM to remind visitors not to approach the crater within a 1.5-km radius. Based on seismicity, visual observations, gas measurements, and crater lake water temperatures through 7 September, the Alert Level remained at 2 (on a scale of 1-4).

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

JMA reported that during 3-7 September six explosive eruptions from Sakura-jima's Showa Crater ejected tephra as far as 1.3 km from the crater. Incandescence from the crater was observed at night. Based on information from JMA, the Tokyo VAAC reported that explosions during 6-11 September often produced plumes that rose to altitudes of 1.8-4.6 km (6,000-15,000 ft) a.s.l. The plumes sometimes drifted N, NE, and SE. On 10 September a pilot observed an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted E.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC), Japan Meteorological Agency (JMA)

Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 5-11 August ash plumes from Batu Tara rose to an altitude of 2.1 km (7,000 ft) a.s.l. and drifted 55-75 km W, WNW, and NW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

On 5 September, AVO reported that satellite views of Cleveland showed no evidence of further eruptive activity since the last explosion on 20 August. Fresh lava within the summit crater was last detected in images in early May. The Volcano Alert Level was lowered to Advisory and the Aviation Color Code was lowered to Yellow.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

In a special bulletin on 4 September at 1700, INSIVUMEH reported that the eruption from Fuego that began 32 hours earlier had ended. During 6-11 September fumarolic plumes rose 100-150 m above the crater and drifted W and NW. Weak explosions generated ash plumes that rose 300-400 m above the crater and drifted W and NW. During 8-9 September incandescent tephra was ejected to a height of 100 m and caused avalanches in the Taniluyá and the Ceniza (SSW) drainages. A 10-20-m-wide lahar traveled SE down the Las Lajas drainage on 9 September, carrying tree trunks and blocks 1.5 m in diameter. During 10-11 September a lava flow traveled 100 m down the Taniluyá drainage.

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

CVGHM reported that on 7 September the Alert Level for Gamkonora was lowered from 3 to 2 (on a scale of 1-4).

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

KVERT reported weak-to-moderate seismic activity from Karymsky during 31 August-7 September. Seismic data indicated that ash plumes possibly rose to an altitude of 2.5 km (8,200 ft) a.s.l. Satellite imagery showed a thermal anomaly on the volcano on 31 August and 1 September. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

During 5-11 September HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kīlauea's Halemaʻumaʻu Crater. The gas plume from the vent continued to deposit variable amounts of spatter and Pele's hair onto nearby areas.

On 4 September HVO geologists observed the Puʻu ʻŌʻō Crater floor and noted lava ponds in the E and S pits, with the N pit being fully crusted over. During 5-11 September glow emanated from the E and S pit craters; lava in the N pit was crusted, but was periodically incandescent on the W edge. A collapse in the roof of the lava tube at the base of the SE flank of Puʻu ʻŌʻō also continued to glow. Lava flows were active above and at the top of the pali. On 11 September a geologist confirmed that lava flows above the pali had advanced to the top of the abandoned Royal Gardens subdivision.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

According to INGEOMINAS, Observatory Vulcanológico and Sismológico de Manizales reported that at 0732 on 9 September a M 3.6 volcano-tectonic earthquake occurred below the main lava dome at Cerro Machín at a depth of 3.2 km, and was felt by nearby residents. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").

Source: Servicio Geológico Colombiano (SGC)

According to INGEOMINAS, on 5 September the Observatorio Vulcanológico and Sismológico de Manizales reported that seismicity at Nevado del Ruiz significantly decreased, both in the number and magnitude of the earthquakes. Field measurements and analysis of satellite imagery continued to show a significant amount of sulfur dioxide in the atmosphere. A steam-and-gas plume rose 400 m and drifted W. Later that day, INGEOMINAS decreased the Alert Level to III (Yellow; "changes in the behavior of volcanic activity").

Source: Servicio Geológico Colombiano (SGC)

CVGHM reported that on 7 September the Alert Level for Paluweh was lowered from 2 to 1 (on a scale of 1-4).

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

Based on visual observations and analyses of satellite data, KVERT reported that during 31 August-7 September a viscous lava flow continued to effuse on the NE flank of Shiveluch's lava dome, and was accompanied by hot avalanches and fumarolic activity. Satellite imagery showed a thermal anomaly over the lava dome during 31 August and 4-5 September; cloud cover prevented observations on the other days. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

CVGHM reported that on 7 September the Alert Level for Sirung was lowered from 2 to 1 (on a scale of 1-4).

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