The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, these notices are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of eruptions during the week, but rather a summary of activity that meet selected criteria. Carefully reviewed, detailed reports are published in the Bulletin of the Global Volcanism Network.

The Icelandic Meteorological Office (IMO) reported that by 23 September around 10 million cubic meters of magma had accumulated beneath Svartsengi since the last eruption within the Reykjanes volcanic system ended on 5 August. Data showed that magma was accumulating at around 4 km depth. The rate of magma accumulation was steady; model calculations based on deformation measurements indicated that by 27 September the volume may reach 11 million cubic meters, a volume that in some previous cases was followed by eruptions. Since the likelihood of an eruption had increased, IMO raised the Volcanic Alert Level System (VAL) to 2 (on a scale of 0-3) on 25 September and concurrently a risk assessment map of the area was also updated.

Source: Icelandic Meteorological Office (IMO)

The Instituto Geofísico del Perú?s (IGP) Centro Vulcanológico Nacional (CENVUL) reported that daily gas-and-steam plumes at Sabancaya rose 300-1,300 m above the crater rim and drifted less than 10 km in multiple directions during 23-29 September. Thermal anomalies on the summit crater floor were detected almost daily. The Alert Level remained at Orange (the third level on a four-color scale) and the public was warned to stay outside of a 12 km radius from the summit.

Source: Instituto Geofísico del Perú (IGP)

The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 22-29 September. Nightly crater incandescence was visible in webcam images. A very small eruptive event was recorded on 27 September. The Alert Level remained at 3 (on a 5-level scale), and the public was warned to be cautious within 2 km of both the Minimadake and Showa craters.

Source: Japan Meteorological Agency (JMA)

The Vanuatu Meteorology and Geohazards Department (VMGD) reported ongoing unrest at Ambae during the month of September based on seismic and satellite data, webcam images, and field observations. Sulfur dioxide emissions were identified in satellite images during 1-10, 12-14, and 16-21 September. A very low-level thermal anomaly was also detected in satellite images during 11 and 20-22 September. Steam and/or gas emissions were visible in satellite and webcam observations on 12 September. The Alert Level remained at 2 (on a scale of 0-5), and the public was warned to stay outside of Danger Zone A, defined as a 2-km radius around the active vents in Lake Voui, and to stay away from drainages during heavy rains.

Source: Vanuatu Meteorology and Geohazards Department (VMGD)

The Vanuatu Meteorology and Geohazards Department (VMGD) reported ongoing unrest at Ambrym during September. A weak thermal anomaly was detected in satellite images on 4 and 12 September. Seismic data confirmed ongoing unrest. The Alert Level remained at 2 (on a scale of 0-5). VMGD warned the public to stay outside of Permanent Danger Zone A, defined as a 1-km radius around Benbow Crater and a 2-km radius around Marum Crater, and to stay 500 m away from the ground cracks created by the December 2018 eruption.

Source: Vanuatu Meteorology and Geohazards Department (VMGD)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 24-30 September. White-and-gray gas-and-ash plumes rose as high as 700 m above the summit on most days and drifted E, NW, and W. White plumes rose as high as 200 m above the summit and drifted E and SW on 26 and 29 September. The Alert Level remained at Level 2 (on a scale of 1-4) and the public was warned to stay 4 km away from the Malupang Warirang Crater.

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

The Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported that eruptive activity at Fuego continued during 23-30 September. Daily Strombolian explosions were recorded by the seismic network at rates of 5-10 per hour. The explosions generated daily gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted as far as 40 km NW, W, and SW. Occasional rumbling sounds, shock waves, and/or sound associated with gas emissions were reported; the shock waves rattled buildings and structures in communities on the SW and W flanks during 23-24 September. Explosions ejected incandescent material 100-200 m above the summit during 27-30 September, sometimes showering the upper flanks with incandescent material. Daily block avalanches descended the flanks, including the Las Lajas (SE), Seca (W), Taniluya (SSW), Trinidad (SSW), Santa Teresa (W), and Ceniza (SSW) drainages, occasionally reaching vegetated areas. Ashfall was reported in areas downwind including Finca Palo Verde (10 km WSW), Yepocapa (12 km SW), Sangre de Cristo (8 km W), El Porvenir (11 km SW), Quisaché (8 km NW), and Soledad (11 km N) during 23-24 September, in Yepocapa during 24-25 September, in areas on the SW flank during 25-26 September, and in Panimache (8 km SW), Sangre de Cristo, Finca Palo Verde, and Yepocapa during 28-29 September. Heavy rain generated lahars in multiple drainages during 22-23, 25, and 28 September. Special reports issued at 1655, at 1707, at 1736, and 1813 on 22 September noted that lahars descended the El Jute (ESE), Las Lajas, Ceniza, Zarco, Mazate, Seca, and Mineral (W) drainages. The lahars that descended the El Jute and Las Lajas drainages were hot and had a sulfur odor. On 23 September lahars descended the Santa Teresa, El Jute, Ceniza, and possibly the Las Lajas based on reports from 1410, 1440, and 1500. Reports issued at 1530 and 1601 on 25 September noted that lahars traveled down the Seca, Mineral, Ceniza, Zarco, and Mazate drainages. Lahars descended the Ceniza, Zarco, and Mazate drainages the next day based on a report from 1940 on 28 September. All of the lahars were characterized as a mixture of water and sediment that carried tree branches, trunks, and blocks as large as 3 m in diameter.

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

The Vanuatu Meteorology and Geohazards (VMGD) reported that unrest continued at Gaua during September. Sulfur dioxide emissions were identified in satellite images during 7, 9-10, and 20 September and steam and/or gas emissions were visible in satellite images rising from the vent during 7, 9, 11, and 17-18 September. A very low thermal anomaly was detected on 14 September. The Alert Level remained at 2 (on a scale of 0-5) and the public was warned to stay away from the main cone.

Source: Vanuatu Meteorology and Geohazards Department (VMGD)

The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin?s summit crater during 24-29 September. Satellite data indicated that the SE part of the flow slightly inflated. Advancement was detected around the SW, S, and SE margins of the flow; the fastest moving part of the flow advanced at a rate of about 5 m per day. Small daily earthquakes were detected by the seismic network daily along with rockfall signals. Weather clouds often obscured satellite and webcam views, though elevated surface temperatures were identified in 29 September satellite views. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued during 24-30 September. Dense gray or white-and-gray ash plumes rose 300-700 m above the summit and drifted in multiple directions. Incandescence at the summit was visible in a few nighttime webcam images. The Alert Level remained at 2 (the second lowest level on a four-level scale) and the public was advised to stay 2 km away from the active crater and 3.5 km away from the N crater wall opening.

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

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that explosions at Karymsky were last observed in August. In September activity was at moderate levels characterized by steam-and-gas emissions and a weak thermal anomaly identified in satellite images; weather clouds sometimes obscured views. On 25 September the Aviation Color Code was lowered to Yellow (the second level on a four-color scale). Dates and times are provided in Coordinated Universal Time (UTC); specific events are indicated in local time where specified.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

The Alaska Volcano Observatory (AVO) reported that on 27 September strong winds in the vicinity of Katmai and the Valley of Ten Thousand Smokes dispersed unconsolidated ash up to 1.8 km (6,000 ft) a.s.l. to the SE. The ash was originally deposited during the Novarupta-Katmai eruption in 1912. The Volcano Alert Level remained at Normal (the lowest level on a four-level scale) and the Aviation Color Code remained at Green (the lowest level on a four-color scale).

Source: US Geological Survey Alaska Volcano Observatory (AVO)