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 Thursday, 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 Japan Meteorological Agency (JMA) reported that the amplitude of volcanic tremors at Asosan began to increase at around 1900 on 12 August, fluctuated for a few days, and further intensified at 1500 on 14 August. During a field survey that same day scientists measured a high sulfur dioxide emission rate of 2,700 tons per day (t/d), notably increased from 700 t/d on 28 July and 1,200 t/d on 6 August. The Alert Level was raised to 3 (on a scale of 1-5) at 1545 and the public was warned that eruptive products may impact areas within 2 km of the crater. Continuous Global Navigation Satellite System (GNSS) data suggested that magma was accumulating beneath Kusasenri. Webcams show no significant changes in conditions within the crater; white plumes rose as high as 900 m above the Nakadake Crater I rim during 12-17 August.

Source: Japan Meteorological Agency (JMA)

The Sezione di Catania - Osservatorio Etneo (INGV) reported eruptive activity at Etna?s summit craters during 10-16 August characterized by explosive activity and ash emissions at both Voragine Crater (VOR) and Northeast Crater (NEC), and effusive activity from several vents within the Valle del Bove. Explosive activity at VOR persisted during most of the week with ash emissions mainly drifting S and SE. Emissions significantly intensified during the afternoon of 13 August and Strombolian activity was visible the afternoon of 16 August. Explosive activity on 17 August generated a notable ash plume that rose around 6 km (19,700 ft) a.s.l. and drifted SE. Several intra-crater explosive episodes at NEC were recorded during the week. A brief explosion on 15 August produced an ash plume that drifted S. A series of short-lived explosions on 16 August produced ash plumes that drifted SE. Ash emissions intensified later that day. Lava effusion from multiple vents was variable through the week. During 10-12 August flows from vents at 1,900 m, 2,090 m, and 2,750 m elevations were active, though by 13 August effusion at the 2,090 m elevation vent had ceased. Early on 14 August a pit crater formed at an elevation of 3,000 m and produced intermittent gas emissions for a brief period. Strombolian activity continued and the leading lava flows from the active vents advanced during 13-16 August, reaching an elevation of 1,395 m between Rocca delle Palombe and Rocca Musarra. On 17 August a new effusive vent opened in Valle del Bove, at an elevation of 2,350 m, which triggered the collapse of the E flank of the Monte Rittmann cone along with an ash emission. The new vent produced a lava flow that traveled 500 m and rapidly cooled. By the afternoon of 17 August, the lava field fed by multiple vents was generally cooling. The vent at 1,900 m elevation remained active and continued to effuse lava with the flow front reaching an elevation of approximately 1,600 m. Overall effusion during 7-17 August covered an approximate area of 1.7 square kilometers and had estimated volumes ranging from 5.6 to 7.6 × 10? cubic meters. The volcano Alert Level remained at Yellow (the second lowest level on a four-level scale) according to the Dipartimento della Protezione Civile.

Source: Sezione di Catania - Osservatorio Etneo (INGV)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and a news source reported that an eruption at Karangetang?s North Crater (Kawah Dua) continued during 12-19 August. Lava began to effuse from North Crater on 9 August, advancing about 700 m S into the saddle between the North and South (Kawah Utama or Main) craters, then advanced W for about 400 m and NNW for about 1 km, igniting vegetation fires. Lava flows continued to be active during 12-18 August and descended 1 km SW. Rumbling was often heard, which was sometimes accompanied by grayish-white puffs that rose as high as 150 m and drifted NNE. Residents in Pehe Village reported that vegetation between the Kinali and Hiung rivers had ignited and was burning. The Alert Level remained at 2 (on a scale of 1-4) and the public was advised to stay 1.5 km away from both craters, with an extension to 2.5 km on the NW and SW flanks of North Crater.

Sources: Antara News,Antara News,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a new eruption at Klyuchevskoy began with Strombolian explosions and lava fountaining at the summit crater on 15 August. The temperature of a thermal anomaly identified in satellite images began increasing at 1541. Activity continued on 16 August and at 2236 the Aviation Color Code (ACC) was raised to Yellow (the second lowest level on a four-color scale). A series of large collapses began in the Apakhonchichsky drainage on the SE flank at 2320 and lasted about 30 minutes. Ash clouds from the collapse and possible explosions rose 7-8 km (22,960-26,250 ft) a.s.l. and drifted 50 km E, though according to the Tokyo Volcanic Ash Advisory Center (VAAC) ash plumes may have risen as high as 9.1 km (30,000 ft) a.s.l. The ACC was raised to Orange at 2343. Strombolian explosions and lava fountaining continued on 17 August and collapsed hot material descended the Apakhonchichsky drainage. Ash plumes rose 6 km (19,680 ft) a.s.l. and drifted 420 km ESE. Gas-and-ash plumes rose to 5.5 km (18,100 ft) a.s.l. on 18 August and drifted 400 km ESE. 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 Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported ongoing eruptive activity at Krakatau during 13-20 August. White-and-gray plumes rose as high as 150 m above the summit on 13 August and drifted in various directions. No emissions were observed the next day. During 16-18 August white, gray, and black plumes rose as high as 400 m above the summit and drifted mainly NW, N, NE, and E. Multiple eruptive events per day were recorded during 16-17 August, and several webcam images showed incandescent material being ejected above the crater. According to a news report, residents of Tejang Village (20 km NNE) on Sebesi Island reported ashfall during 16-18 August and adverse health effects due to ash in the air. The Alert Level remained at 3 (on a scale of 1-4) and the public was advised to stay 3 km away from summit.

Sources: Antara News,Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that seismicity at Sinabung is continuing to increase. There was a notable increase in the number of deep volcanic earthquakes and signals indicating emissions during 1-12 August. Additionally, some low-frequency and hybrid earthquakes were detected. Emissions had become denser, were grayish-white, and rose as high as 1 km above the summit. The Alert Level remained at 2 (on a scale of 1-4), though at 1000 on 13 August the exclusion zone was increased to 3 km from the summit and 4.5 km on the SE flank.

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

The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 10-17 August. Crater incandescence was visible in nighttime webcam images. The monitoring networks recorded a total of 14 eruptive events and one explosion. Eruptive events during 10-15 August generated ash plumes that rose as high as 1.8 km above the summit and drifted in multiple directions. Emissions were sometimes continuous, notably during 0020-0150 on 12 August, during 1906-2220 on 14 August, and during 1019-1150 on 15 August. An explosion at 2232 on 13 August ejected large blocks 800-1,100 m from the vent; plume characteristics were not reported. 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 Wellington Volcanic Ash Advisory Center (VAAC) reported that daily ash-and-gas plumes at Ambae were identified in satellite and webcam images during 13-18 August rising 1.5-4.6 km (5,000-15,000 ft) a.s.l. and drifting in multiple directions. Occasionally the ash emissions were intermittent, and sulfur dioxide plumes were also occasionally identified. Weather clouds sometimes obscured views. The Alert Level remained at 3 (on a scale of 0-5), and the public was warned to stay outside of Danger Zone B, defined as a 3-km radius around the active vents in Lake Voui, and to stay away from drainages during heavy rains.

Source: Wellington Volcanic Ash Advisory Center (VAAC)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 13-19 August. White plumes rose as high as 400 m above the summit on 13 August. On the other days white-and-gray ash plume rose as high as 1.5 km above the summit and drifted in various directions. 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 Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin?s summit crater during 12-19 August based on webcam and satellite images. The flow advanced mainly E. Minor earthquakes were detected daily, likely associated with rockfalls on the growing dome. Weather clouds often obscured webcam and satellite views during most of the week. 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 activity at Ibu continued during 13-19 August, with daily eruptive events recorded by the seismic network. Gray or white-to-gray ash plumes rose 300-800 m above the summit and drifted in multiple directions, especially towards the N and NE on most days; emissions were not visible on 19 August. 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 Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing eruptive activity at Kanlaon during 12-18 August. The seismic network recorded 0-7 daily volcanic earthquakes; the counts included 1-3 daily periods of tremor during 14-15 and 17 August, lasting two minutes to one hour and 34 minutes. Sulfur dioxide emissions ranged from 887 to 3,304 tonnes per day. Volcanic emissions rose as high as 200 m above the summit and drifted NNE, ENE, and E. A grayish ash emission lasting 92 minutes on 13 August rose 200 m above the summit and drifted ENE. On 14 August there were five ash emissions and on 15 August there were three ash emissions, each lasting five minutes to just over an hour. One of the 14 August ash emissions, at 0549, was grayish and rose 200 m above the summit and drifted N. On 17 August one ash emission was recorded for 94 minutes. The Alert Level remained at 2 (on a scale of 0-5); the public was warned to stay out of the 4-km-radius Permanent Danger Zone (PDZ) and pilots were advised to avoid flying close to the summit.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)