Asamayama (Japan) – Report for 21 August-27 August 2019 – NEW

JMA reported that at 1928 on 25 August a small eruption at Asamayama generated a grayish-white ash plume that rose 600 m above the crater rim and drifted E. Large blocks were also ejected from the crater. Minor ashfall was reported in Karuizawa Town, Nagano Prefecture, about 4 km E. The plume then turned white and continuous emissions rose 200 m during 25-26 August. The Alert Level remained at 2 (on a scale of 1-5).

Source: Japan Meteorological Agency (JMA)

Shishaldin (United States) – Report for 21 August-27 August 2019 – NEW

AVO reported that during 21-28 August continuous, low-level tremor at Shishaldin was recorded by the seismic network and elevated surface temperatures were often visible in satellite images. The spatter cone in the crater had grown and partially filled the summit crater. NOAA scientists took video of the eruption during an overflight on 17 August and noted repetitive minor explosive activity within the summit crater. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

Stromboli (Italy) – Report for 21 August-27 August 2019 – NEW

INGV reported that a paroxysmal explosive event at Stromboli began at 1216 on 28 August with a series of explosions likely from the Area C-S (South Central crater area). The event of strongest intensity occurred at 1217, generating an ash plume that rose more than 2 km above the crater area and a pyroclastic flow that traveled down the Sciara del Fuoco and several hundred meters out to sea. The report noted a similarity in intensity of the eruption to the 3 July paroxysmal event based on the seismic data.

Source: Sezione di Catania – Osservatorio Etneo (INGV)

Tangkubanparahu (Indonesia) – Report for 21 August-27 August 2019 – NEW

PVMBG reported that during 19-25 August phreatic events at Tangkubanparahu’s Ratu Crater continued to produce sometimes dense gray-to-white plumes that rose as high as 200 m above the vent, and dense black ash plumes that rose as high as 180 m. Ashfall was localized around Ratu Crater. The seismic network recorded continuous tremor. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to stay 1.5 km away from the active crater.

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

AVO Cleveland YELLOW/ADVISORY – Unrest likely continues; nothing observed in satellite data

Aug 29, 2019 22:08 – Nothing noteworthy observed in cloudy satellite images over the past day. Nothing significant was detected in seismic data and no activity was recorded by regional or local infrasound arrays during the last 24 hours.

Episodes of lava effusion and explosions can occur without advance warning. Explosions from Cleveland are normally short duration and only present a hazard to aviation in the immediate vicinity of the volcano. Larger explosions that present a more widespread hazard to aviation are possible, but are less likely and occur less frequently.

Cleveland …

AVO Shishaldin ORANGE/WATCH – Low-level eruption continues; moderately elevated surface temps in satellite data

Aug 29, 2019 22:08 – Low-level eruptive activity continues at Shishaldin volcano. Seismicity remains elevated with steady tremor detected over the past day. Satellite views of the volcano showed moderately elevated surface temperatures at the summit in a few images with little or no cloud cover.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic network, and distant infrasound and lightning networks.

AVO Semisopochnoi ORANGE/WATCH – Seismic unrest at low levels; nothing significant seen in cloudy satellite data

Aug 29, 2019 22:08 – Low-level eruptive activity has likely declined at Semisopochnoi. Seismic activity over the past day has been relatively minor and the levels of seismic tremor have declined. Nothing significant was observed in cloudy satellite images.

Semisopochnoi is monitored with an on-island seismic network and remotely by satellite and lightning sensors. An infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a slight delay (approximately 13 minutes) if atmospheric conditions permit.

AVO Veniaminof GREEN/NORMAL – Alert level changed to GREEN/NORMAL earlier today due to return to background

Aug 25, 2019 22:00 – Earlier today, AVO lowered the Aviation Color Code to GREEN and the Volcano Alert Level to NORMAL due to a return to background at Veniaminof.

Veniaminof volcano is monitored with a local real-time seismic network, which will typically allow AVO to detect changes in unrest that may lead to a more significant explosive eruption. AVO combines seismic, infrasound, lightning, and satellite data for rapid detection of such events.