Volcano World

AVO reported that a satellite image of Great Sitkin acquired at 0932 on 22 July showed a small area of uplift, about 50 m in diameter, and elevated surface temperatures associated with the feature. These observations suggested magma rising near the surface, prompting AVO to raise the Aviation Color Code and the Volcano Alert Level to Orange and Watch, respectively. Small earthquakes were recorded during 23-25 July. A 26 July satellite image confirmed that the feature was a lava dome, and that it had grown to 130 m in diameter. Seismic data suggested that the dome probably emerged sometime during 14-22 July.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

AVO lowered the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory for Semisopochnoi on 22 July, noting that explosive activity had not been detected since 12 July. Seismicity continued to be elevated during 23-27 July. Robust steam emissions were visible in webcam views during 22-24 July and sulfur dioxide plumes were identified in satellite images on 23 July. Weather clouds obscured views during 24-27 July.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

PVMBG reported that a phreatic eruption at Sirung was recorded at 1644 on 21 July. A white-and-gray ash plume rose 2 km above the summit and drifted N. The report noted that the event was preceded by an increase in tremor amplitude that lasted about 10 hours; no volcanic earthquakes indicating magma movement were recorded and tremor amplitude did not notably increase. The Alert Level was raised to 2 (on a scale of 1-4), with visitors and tourists prohibited within a 1.5 km radius of Sirung.

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

JMA reported ongoing explosions at Suwanosejima's Ontake Crater during 19-26 July and that crater incandescence was visible on some nights. There were 31 explosions recorded on 22 July after two days of no explosions. An explosion at 1500 on 23 July produced an ash plume that rose 1.6 km and ejected bombs 200 m. Eruption plumes during 23-26 July rose as high as 2.3 km; it was unknown if bombs were ejected from the crater due to weather conditions. The Alert Level remained at 3 and the public was warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

PHIVOLCS lowered the Alert Level for Taal to 2 (on a scale of 0-5) on 23 July, noting that no eruptions had been recorded since the period of phreatomagmatic activity during 1-9 July. Additionally, an overall decrease was evident in multiple monitoring parameters. Sulfur dioxide emissions peaked at 22,628 tonnes/day on 4 July and declined to an average of 4,763 tonnes/day during 8-22 July. Steam plumes continued to be generated from the lake, rising 10-1,000 m, and lake upwelling was generally less vigorous. The DROMIC report stated that 794 people were in evacuation centers or private residences by 26 July. PHIVOLCS reminded the public that the entire Taal Volcano Island is a Permanent Danger Zone (PDZ).

Sources: Disaster Response Operations Monitoring and Information Center (DROMIC),Philippine Institute of Volcanology and Seismology (PHIVOLCS)

OVSICORI-UNA reported that a one-minute-long eruption at Turrialba was recorded at 1130 on 23 July, though weather clouds prevented visual confirmation of an eruption plume. Ash fell in areas 3.5 km W.

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

GeoNet reported that crater incandescence at Whakaari/White Island, first seen on 30 June, continued to be visible in nighttime webcam images. The incandescence was attributed to high-temperature gasses. Additionally, the gas ratio of carbon dioxide to sulfur dioxide declined, indicating ongoing degassing from a shallow magma source. The Volcanic Alert Level was raised to 2 and the Aviation Color Code was raised to Yellow on 26 July.

Source: GeoNet

JMA reported that incandescence from Minamidake Crater (at Aira Caldera?s Sakurajima volcano) was visible at night during 19-26 July. A very small eruptive event was recorded on 19 July. The sulfur dioxide emission rate was relatively elevated at 1,000 tons per day on 21 July. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Source: Japan Meteorological Agency (JMA)

Based on satellite and wind model data, the Darwin VAAC reported that during 21-26 July ash plumes from Dukono rose to 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted NE, E, and SE. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC),Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

According to volcanologists in Severo-Kurilsk (Paramushir Island), about 7 km E of Ebeko, explosions during 16-17 July produced ash plumes that rose as high as 3 km (10,000 ft) a.s.l. and drifted E. Thermal anomalies were identified in satellite images during 16 and 20-22 July. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)