Increased seismicity at Agung, as well as the severity of past eruptions, prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4). The report noted that volcanic earthquakes (VA) began to be recorded on 10 August and shallow volcanic earthquakes (VB) began to be recorded on 24 August. Local tectonic earthquakes were also recorded and began to increase consistently on 26 August. PVMBG warned the public to stay at least 3 km away from the crater. On 13 September a climber observed a sulfatara plume rising from the bottom of the crater as high as 50 m above the crater rim. During 14-18 September four earthquakes centered around Agung were felt. On 18 September PVMBG reported that the number of VA and VB events continued to increase; the Alert Level was increased to 3. The exclusion zone was increased to 6 km, with an additional expansion to 7.5 km in the N, SE, and SSW directions. Elevations above 950 m were also restricted.

A VEI 5 eruption during 1963-64 produced pyroclastic flows and lahars that caused extensive damage and resulted in more than 1,100 deaths.

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

PVMBG reported that during 8 July-14 September measurements indicated an increase in water temperature at Sileri Crater lake (Dieng Volcanic Complex) from 90.7 to 93.5 degrees Celsius. Soil temperatures also increased, from 58.6 to 69.4 degrees Celsius. At Timbang Crater temperatures in the lake increased from 57.3 to 62.7, and in the soil they decreased from 18.6 to 17.2. The report noted that conditions at Timbang Crater were normal. Temperature increases at Sileri, along with tremor detected during 13-14 September, prompted PVMBG to raise the Alert Level to 2 (on a scale of 1-4). PVMBG warned the public to stay at least 1 km away from the crater rim, and for residents living within that radius to evacuate.

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

Based on visual observations, KVERT reported that on 17 September explosions at Zhupanovsky generated gas-and-steam plumes with small amounts of ash that rose to altitudes of 6-7 km (19,700-23,000 ft) a.s.l. and drifted 20 km SW. The Aviation Color Code was raised from Green to Orange, the second highest level on a 4-color scale. About 30 minutes later satellite images showed ash plumes drifting 10 km E. Later that day gas-and-steam plumes rose 4 km (13,100 ft) a.s.l. The Aviation Color Code was lowered to Yellow, and then on 20 September it was lowered to Green.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

JMA reported that during 4-11 September there were 52 events detected at Showa Crater (at Aira Caldera’s Sakurajima volcano), seven of which were explosive and ejected material as far as 500 m. Ash plumes rose as high as 2.4 km above the crater rim. Crater incandescence was observed most nights. The Alert Level remained at 3 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)

KVERT reported that during 8-15 September a lava flow continued to move down the W flank of Bezymianny's dome, and incandescence from the dome was visible at night. A thermal anomaly was identified in satellite images during 8-9 and 12-13 September. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

AVO reported that during 13-19 September nothing significant was observed in partly to mostly cloudy satellite images of Bogoslof, and no activity was detected in seismic or infrasound data. Weakly elevated surface temperatures were identified in satellite images during 13-14 and 16-17 September, indicating ongoing unrest. On 17 September discolored ocean water was visible in satellite data, possibly representing outflow from the crater. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

AVO reported that during 13-19 September nothing significant was observed in often cloudy satellite images and web camera views of Cleveland; elevated surface temperatures were identified in satellite images during 13-15 September and minor steaming was noted during 17-19 September. Nothing noteworthy was detected in seismic or infrasound data. 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 analyses of satellite imagery, wind model data, and notices from PVMBG, the Darwin VAAC reported that during 13-16 and 18 September ash plumes from Dukono rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SW, W, and NW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Based on observations by volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 13-14 September generated ash plumes that rose 2.2 km (7,200 ft) a.s.l. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Based on INSIVUMEH notifications, CONRED reported that Fuego’s ninth effusive eruption phase in 2017 began on 13 September. Explosions generated ash plumes that rose 1.2 km above the crater and drifted 15 km W and SW, causing ashfall in communities downwind including San Pedro Yepocapa (8 km N), El Porvenir (8 km ENE), and Sangre de Cristo (8 km WSW). Pyroclastic flows descended the Seca (Santa Teresa) ravine on the W flank. The eruptive phase ended about 35 hours later. INSIVUMEH noted that on 14 September, explosions generated ash plumes that rose 750 m and drifted 10 km W and SW. Shock waves from some explosions vibrated nearby structures. A lava flow was active in the Santa Teresa ravine. Explosions on 15 September produced ash plumes that rose as high as 750 m and drifted 5 km NW and SW. The lava flow was 300 m long. During 17-18 September ash plumes from explosions rose almost 1 km and drifted W and SW. Incandescent material was ejected 250 m above the crater rim, and caused avalanches of material around the crater area. Ashfall was reported in areas including Panimaché I and II (8 km SW), Morelia (9 km SW), and El Porvenir.

Sources: Coordinadora Nacional para la Reducción de Desastres (CONRED), Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

Based on satellite data, KVERT reported that ash explosions at Karymsky occurred at 0420 on 20 September, producing an ash cloud that drifted 95-100 km NNE. The Aviation Color Code was raised to Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

During 13-19 September HVO reported that the lava lake continued to rise, fall, and spatter in Kīlauea's Overlook crater. Webcams recorded incandescence from long-active sources within Puʻu ʻŌʻō Crater and from a small lava pond in a pit on the W side of the crater. The 61G lava flow, originating from a vent on Puʻu ʻŌʻō Crater's E flank, continued to enter the ocean at Kamokuna. Surface lava flows were active above and on the pali, and on the coastal plain. On 13 September geologists noted that several prominent cracks running parallel to the coastline had widened in the past two weeks, underscoring the potential for bench collapse into the sea.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

KVERT reported that on 8 September a weak thermal anomaly at Klyuchevskoy was identified in satellite images. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Each day during 12-19 September CENAPRED reported 141-299 steam and gas emissions from Popocatépetl. Cloud cover often prevented observations, though gas-and-steam plumes were visible daily. During 12-13 September there were 22 explosions detected, four of which generated emissions with minor amounts of ash and ejected incandescent tephra. An explosion was detected at 1820 on 14 September. On 19 September a plume with low ash content rose 1 km. CENAPRED stated that there was no significant increase in activity at Popocatépetl related to the M 7.1 earthquake, centered beneath Puebla (45 km E), that occurred at 1314. The Alert Level remained at Yellow, Phase Two.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

On 15 September, in a special report, IG summarized recent activity at Reventador noting lava flows during 24 June-1 July and 23-24 August, periods of frequent small explosions in August, and periods of explosions that were less frequent but moderate-to-large in size during July and September. Data indicated no changes in the internal and external activity of the volcano, suggesting that the eruption will continue with alternation of effusive and explosive activity in the next days to weeks.

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

Observatorio Vulcanológico del Sur del IGP (OVS-IGP) and Observatorio Vulcanológico del INGEMMET (OVI) reported that explosive activity at Sabancaya continued to decline; there was an average of 29 explosions recorded per day during 11-17 September. The earthquakes were dominated by long-period events and signals indicating emissions, with fewer numbers of hybrid events. Gas-and-ash plumes rose 2.5 km above the crater rim and drifted no more than 30 km E and SE. The MIROVA system detected one thermal anomaly. The report warned the public not to approach the crater within a 12-km radius.

Sources: Instituto Geológico Minero y Metalúrgico (INGEMMET), Instituto Geofísico del Perú (IGP)

KVERT reported that a thermal anomaly over Sheveluch was identified daily in satellite images during 8-15 September. Several explosive events during 8-13 September generated ash plumes that rose 9-10 km (29,500-32,800 ft) a.s.l. and drifted about 400 km NW, E, and SE. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

Based on observations by PVMBG, webcam and satellite images, and model data, the Darwin VAAC reported that during 13-16 and 18 September ash plumes from Sinabung rose 3-7.5 km (12,000-18,000 ft) a.s.l. and sometimes drifted ESE, SE, SW.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

OVSICORI-UNA reported that events at Turrialba at 1555 on 13 September and 0600 on 14 September generated plumes that rose 300 m above the crater rim and drifted NW and W. Another event at 0703 on 18 September produced a plume that rose 400 m.

Source: Observatorio Vulcanologico y Sismologico de Costa Rica-Universidad Nacional (OVSICORI-UNA)