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 Sezione di Catania - Osservatorio Etneo (INGV) reported eruptive activity at Etna?s summit craters during 27 July-2 August characterized by sporadic explosive activity and ash emissions at Northeast Crater (NEC) and Bocca Nuova Crater (BN), Strombolian activity and lava effusion at Voragine Crater (VOR), and gas emissions at Southeast Crater. Strombolian activity began at VOR at 0330 on 30 July. The explosive activity gradually intensified during the morning, which produced ash plumes that drifted NW, and transitioned to lava fountaining. The Aviation Color Code (ACC) was raised to Yellow (the second lowest color on a four-color scale) at 0407 and to Orange at 0424. Ash plumes rose to 7 km (23,000 ft) a.s.l.; the ACC was raised to Red at 0533. Lava flows from Strombolian activity at VOR advanced into the Northeast Crater (NEC), and ash emissions drifted SW. At around 0959 a small pyroclastic flow traveled from VOR towards the upper part of the Valle del Bove, and at around the same time ash emissions became less intense. Minor ashfall was reported in Bronte (15 km WNW). Strombolian activity at VOR began to decrease at 1030 and ceased at 1300, though intense ash emissions persisted. By 1743 ash emissions had declined and were characterized as diffuse; the ACC was lowered to Orange. Strombolian activity at VOR resumed at 1850 and gradually intensified. By 1932 Strombolian activity was strong and ash plumes were again rising to 7 km a.s.l.; the ACC was raised to Red. Ashfall was reported in the Monte Denza area (6 km SSW). At 2049 a lava flow from two aligned vents along a new fissure that opened on the upper NE flank of VOR, at 2,700 m elevation, advanced into Northeast Crater (NEC) and spread into a flow field in the Valle del Leone (upper sector of the Valle del Bove). The fissure opened in the same area as the fissures that produced lava flows in late June and early July. The lava flow reached Monte Simone and split into three branches; the smallest advanced into the Monte Simone crater while the other two flows advanced around the cone on either side. The northern branch stopped at 1,990 m elevation while the southern branch stopped at 1,950 m elevation. Intense Strombolian activity stopped at 0140 on 31 July, though very minor ash emissions continued along with active lava flows at the summit area. At 0543 the ACC was lowered to Orange. The distal end of the flow field was no longer advancing on 1 August and cooling, though flows closer to the vent were supplied with lava and continued to slowly advance. INGV staff conducted a field visit on 2 August and observed no activity. The ACC was lowered to Yellow at 1245 that same day. The volcano Alert Level remained at Yellow (the second lowest level on a four-level scale) according to the Dipartimento della Protezione Civile.

Sources: Dipartimento della Protezione Civile,Sezione di Catania - Osservatorio Etneo (INGV)

The Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported that eruptive activity at Fuego continued during 29 July-5 August with an escalation of activity beginning on 2 August. During 29 July-2 August daily Strombolian and Vulcanian explosions recorded by the seismic network, at rates of 6-11 per hour, generated gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted as far as 40 km SW, W, and NW. Rumbling sounds, shock waves, and/or sounds associated with explosions were reported daily. Explosions occasionally ejected incandescent material as high as 300 m above the summit and onto the flanks, causing incandescent block avalanches to descend the flanks; notably avalanches descended the Seca (W), Taniluyá (SSW), Ceniza (SSW), Las Lajas (SE), and Honda drainages, sometimes reaching vegetated areas. Ashfall was reported in areas downwind during 1-2 August, including Panimaché, Morelia, Santa Sofía, El Porvenir, San Pedro Yepocapa, and Sangre de Cristo. Normally the seismic network records 250-350 explosions per day, though at around 1430 on 2 August the eruptive pattern changed. Explosions became nearly continuous, emissions and crater incandescence were observed[EV2.1], and acoustic tremor signals had characteristics not recorded since 5 June 2025. Incandescent lava fragments and blocks were ejected 100-200 m above the summit, with large amounts of the ejecta falling into the Ceniza and Seca-Santa Teresa drainages. Starting at about 0600 on 3 August ash-and-gas emissions intensified along with the amplitude of seismic signals. Crater incandescence continued to be visible, and pyroclastic flows descended the Ceniza and Seca drainages 2-3 km. Strombolian activity intensified during 0830-1150 with denser and larger ash-and-gas plumes, increased seismicity, and pyroclastic flows that traveled as far as 5 km down the Seca. Activity progressively increased during the day; by 1600 a total of nine major events had been identified based on webcam images and field reports, which produced multiple pyroclastic flows that traveled 5-7 km down the Seca. Ash-and-gas plumes rose as high as 2.4 km above the summit and drifting more than 40 km W. Ashfall was reported in San Pedro Yepocapa, Chimaltenango (9 km NW). By 2000 ash plumes had drifted as far as 80 km W, affecting the airspace of the departments of Chimaltenango and Suchitepéquez, and ashfall continued in San Pedro Yepocapa. New pulses of increased activity were evident in Real-time Seismic Amplitude Measurement (RSAM) data. Pyroclastic flows continued to descend the Ceniza and Seca drainages. The Coordinadora Nacional para la Reducción de Desastres (CONRED) reported that evacuations were underway in the hamlet of El Porvenir and the village of Las Lajitas, in the municipality of San Juan Alotenango. Authorities recommended self-evacuation elsewhere. The government declared an Orange Alert at the national level and a Red Alert for the department of Escuintla, and Emergency Operations Centers were activated. Explosivity intensified at 2235 and was around the start of the most intense phase of the eruption. Lava fountains were observed rising 200-300 m above the summit. Incandescent material fell onto the upper flanks in all directions and detached blocks descended to vegetated areas. Ash plumes were identified in satellite images at distances as far as 130 km W, reaching the Pacific coast. Pyroclastic flows continued to descend the Seca, Taniluyá, and Ceniza drainages 5-7 km, and at 0115 on 4 August also descended the Las Lajas and Honda drainages on the SE flank. Tremor signals were constant with increasingly larger amplitudes. During 0215-0730 on 4 August pyroclastic flows were recurrent and larger in the Seca, Taniluyá, Ceniza, Las Lajas, and Honda drainages, and possibly descended into the Trinidad and El Jute drainages. Ashfall increased in the vicinity of the drainages and residents reported sulfur odors. The ejection of incandescent material as well as ash-and-gas emissions were constant. Pyroclastic flows continued to descend the W flank through the day and by 1600 there was an abundant amount of ash suspended in the air. Ashfall was reported in the municipalities of San Pedro Yepocapa and Acatenango. CONRED reported that there were 1,522 people in four evacuation shelters in the department of Escuintla and in one in Sacatepéquez. By 2300 on 4 August tremor was continuous but characterized as weak. Moderate explosions produced gas-and-ash emissions and ejected incandescent material 100-200 m above the summit. Deposited material on the upper flanks was unstable; collapses generated incandescent block avalanches in the Ceniza and Seca drainages. By 0645 on 5 August, 45 hours after onset of increased activity, average seismic amplitude had small variations by had returned to baseline levels. Explosions remained at moderate levels and produced gas-and-ash emissions that rose as high as 3.4 km above the summit and drifted W and NW. Ejected incandescent material rose 100-150 m above the summit. Pyroclastic flows continued to descend the flanks, primarily to the SW. By 1030 on 5 August the intense eruptive phase was over and activity was at normal eruptive levels. Weak to moderate explosions occurred at a rate of 4-6 per hour, incandescent material was ejected 100-200 m above the crater, and ash plumes rose as high as 1.1 km above the summit. The number of evacuees increased to 1,680 people.

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

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported ongoing eruptive activity at Krakatau during 30 July-5 August. White plumes were visible on most days rising 100 m above the summit; weather conditions prevented views during 31 July-1 August. According to the Darwin Volcanic Ash Advisory Centre (VAAC) a dense steam plume with possible ash was visible in satellite images rising 1.5 km (5,000 ft) a.s.l. and drifting SW. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 2 km away from the summit.

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

The Servicio Geologico Colombiano (SGC) reported that eruptive activity at Puracé began to increase on 20 July and continued to intensify. By 1 August the seismic network recorded increases in the intensity of continuous tremor and signals indicating ash emissions. Gas-and-ash emissions had risen as high as 3.4 km above the crater rim and the temperature of ejecta was as high as 140 degrees Celsius. Sulfur dioxide flux peaked at 4,200 tons per day (t/d) and soil-measured carbon dioxide levels reached a concentration of 688 parts per million. Ground deformation persisted in the area between the Puracé, Piocollo, and Curiquinga volcanoes. SGC noted that the data represented the highest values recorded at Puracé; at 1130 the Alert Level was raised to Orange (the second highest level on a four-color scale) and the public was warned to stay away from the Puracé, Piocollo, and Curiquinga volcanoes. During 2-5 August signals associated with fluid movement (long-period earthquakes and spasmodic tremor) continued to be located mainly beneath Puracé at depths less than 1 km. Although sulfur dioxide and carbon dioxide emissions fluctuated and decreased overall, levels remained above baseline; sulfur dioxide averaged 1,965 t/d on 4 August and 1,010 t/d on 5 August. Seismic activity associated with rock fracturing processes continued at low levels with signals located at depths of 1-3 km. Ash plumes rose to lower heights, though ashfall continued to impact residents. Six ash emissions during 1-2 August rose as high as 1 km above the crater rim and drifted W and NW, causing ashfall in the N part of Popayán (28 km NW) and in the rural settlements of Cristales (NW), Pisanrabó, Tabío, and Hispala (32 km NW) in the municipality of Puracé. Three ash plumes rose up to 500 m above the crater rim and drifted W during 2-3 August, causing ashfall in Cristales, Loma Linda, and 20 de Julio villages, in the municipality of Puracé, and in the municipal seat of Coconuco. Two ash emissions during 3-4 August as high as 600 m above the crater rim and drifted W. Residents in Alto Anambío (7 km NNW), Loma Linda-Cristales, and 20 de Julio reported hearing loud sounds associated with an ash emission that occurred at 1925 on 3 August. Two ash emissions occurred during 4-5 August and caused ashfall in Cobaló (11 km W), San José, Las Estrella (40 km NW), and Agua Amarilla. One of the ash emissions produced a loud noise heard by residents of Cristales at 2200 on 4 August.

Source: Servicio Geológico Colombiano (SGC)

The Washington Volcanic Ash Advisory Center (VAAC) reported that ash plumes at Telica were identified in webcam and satellite images during 30 July-1 August rising to 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifting W and SW.

Source: Washington Volcanic Ash Advisory Center (VAAC)

The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 27 July-3 August. The monitoring networks recorded a total of 36 eruptive events and three explosions. Multiple eruptive events per day during 27-29 July and 31 July-2 August generated ash plumes that rose 1-3 km above the summit and sometimes drifted E, SE, and S. Emissions were sometimes continuous, notably during 0351-0430 on 28 July and from 2334 on 2 August to 0030 on 3 August. Large blocks were occasionally ejected as far as 1.1 km from the vent. An explosion at 2059 on 29 July generated an ash plume that rose 1.6 km above the summit and drifted S. At 0002 on 2 August an explosion produced an ash plume that rose 2.2 km above the summit and ejected large blocks 500-700 m from the vent. An ash plume from an explosion at 2334 on 2 August rose 3 km above the summit and drifted S. Crater incandescence was visible in nighttime webcam images during 31 July-3 August. 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 ash plumes at Ambae were identified in satellite images rising 3 km (10,000 ft) a.s.l. and drifting SE on 30 July and rising 4.6 km (15,000 ft) a.s.l. and drifting SE on 4 August. 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.

Sources: Vanuatu Meteorology and Geohazards Department (VMGD),Wellington Volcanic Ash Advisory Center (VAAC)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 30 July-5 August. Daily white-and-gray ash plume rose 500-900 m above the summit and drifted mainly NW, N, NE, and E. 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 29 July-5 August based on webcam and satellite images. The flow advanced mainly ESE. Minor earthquakes were detected daily. Weather clouds often obscured webcam and satellite views during most of the week, though minor steaming was occasionally observed in satellite images. Elevated surface temperatures were identified in satellite images during 4-5 August. 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 30 July-5 August, with daily eruptive events recorded by the seismic network. Daily gray ash plumes rose 200-800 m above the summit and drifted N, NE, and SE. 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 Hawaiian Volcano Observatory (HVO) reported that the eruption within Kilauea?s Kaluapele summit caldera, characterized by episodic fountaining, incandescence, and intermittent spatter from craters along the SW margin of Halema`uma`u Crater, continued at variable levels during 29 July-5 August. Incandescence at the N vent was mostly intermittent during the week and occasional flames were visible through 2 August. Incandescence at the S vent was intermittent mainly during the last part of the week. A crack, slightly upslope of the S vent, exposed hot material at about 0209 on 30 July causing a prominent bright feature in webcams; glow from the crack sometimes visible during the rest of the week. The Volcano Alert Level remained at Advisory and the Aviation Color Code remained at Yellow.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity continued at Lewotobi Laki-Laki during 30 July-5 August. Multiple daily gray ash plumes rose 200-1,200 m above the summit and drifted in various directions. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 5 km away from the center of Laki-Laki.

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