Report for Stromboli
INGV reported that during 1-7 August activity at Stromboli was characterized by ongoing explosions from two vents in Area N (North Crater area) and two vents in Area C-S (South-Central Crater area). Low-intensity explosions from the N1 vent (Area N) ejected mostly ash, with some course material, 80-150 m high at a rate of 2-6 explosions per hour. The N2 vent (Area N) emitted gases. No explosions occurred at the S1 and C vents in Area C-S; low-intensity explosions at two S2 vents ejected coarse material 80-150 m high at a rate of 3-4 explosions per hour.

Report for Krakatau
PVMBG reported that the eruption at Anak Krakatau continued during 3-9 August. Several eruptive events occurred on 3 August (at 0034, 0115, and 1540), sometimes producing dense black ash plumes that rose as high as 1.5 km above the summit and drifted SW. At 0926 on 4 August a dense gray-to-black ash plume rose 1.5 km and drifted N. Incandescence at or near the vent was seen in nighttime photos on most days. Diffuse white plumes were visible rising from the volcano during 7-8 August. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay at least 5 km away from the crater.

Report for Merapi
BPPTKG reported that the eruption at Merapi continued during 29 July-4 August. Seismicity remained at high levels. As many as 34 lava avalanches traveled down the Bebeng drainage on the SW flank, reaching a maximum distance of 1.8 km. The volumes of both the SW and central lava domes were unchanged based on photo analyses. The Alert Level remained at 3 (on a scale of 1-4), and the public was warned to stay 3-7 km away from the summit based on location.

Report for Semeru
PVMBG reported that the eruption at Semeru continued during 3-9 August. Eruptive events recorded at 0810 on 3 August, 0628 on 4 August, 1245 on 5 August, and 0720 on 6 August produced ash plumes that rose 500-700 m above the summit and drifted SW and N. The Alert Level remained at 3 (on a scale of 1-4). The public was warned to stay at least 5 km away from the summit, and 500 m from Kobokan drainages within 17 km of the summit, along with other drainages originating on Semeru, including the Bang, Kembar, and Sat, due to lahar, avalanche, and pyroclastic flow hazards.

Report for Lewotolok
PVMBG reported that the Strombolian eruption at Lewotolok continued during 2-9 August. Daily white or white-and-gray emissions rose as high as 400 m above the summit and drifted in multiple directions. Photos in some posted reports showed Strombolian activity. The Alert Level remained at 3 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater and 4 km away from the crater on the SE flank.

Report for Taal
PHIVOLCS reported increases in both sulfur dioxide emissions at Taal and activity in Main Crater Lake. Sulfur dioxide emissions averaged 1,289 tonnes per day from May to mid-June, and increased to an average of 4,952 tonnes per day during 15 July-3 August. Sulfur dioxide emissions further increased to 12,125 and 17,141 tonnes per day on 3 and 7 August, respectively, prompting PHIVOLCS to issue advisories. Vog was present over the W part of Taal Caldera during 2-3 August; dense vog in Laurel and Banyaga (Agoncillo, Batangas Province) also damaged vegetation. A sulfur odor was reported by residents of Tagaytay City and Bugaan East. Upwelling gasses and hot fluids in the lake, and voluminous steam-rich plumes rising as high as 2.8 km above the lake, were visible during 1-9 August. Recent low-frequency seismic events and tremor were characterized as above background. The Alert Level remained at 1 (on a scale of 0-5), and PHIVOLCS reminded the public that the entire Taal Volcano Island was a Permanent Danger Zone (PDZ).

Report for Suwanosejima
JMA reported that the number of explosions at Suwanosejima's Ontake Crater increased during 2-8 August, when around 30 were recorded; nine of those were detected on 7 August. During 7-8 August eruption plumes rose as high as 2 km above the crater rim and mingled with weather clouds. Large ballistics were ejected 600 m from the crater’s center. Incandescence from the crater was visible at night. The Alert Level remained at 2 and the public was warned to stay 1 km away from the crater.

Report for Aira
JMA reported that nighttime incandescence at Minamidake Crater (at Aira Caldera’s Sakurajima volcano) was visible during 1-8 August. The seismic network recorded 25 eruptive events and seven explosions. Volcanic plumes rose as high as 2.8 km above the crater rim and material was ejected material as high as 1.3 km above the summit. The Alert Level remained at 3 (on a 5-level scale), and residents were warned to stay 2 km away from the crater.

Report for Ioto
JMA reported that minor eruptive activity off the coast at Ioto (Iwo-jima) had been visible daily during 11-31 July. On 14 July pumice pieces from the eruption washed up onto the shore at Onohama and were photographed during a field survey conducted by the National Research Institute for Earth Science and Disaster Prevention. JMA scientist visited the site on 31 July and confirmed the pumice deposits on the beach. They saw eruptive activity every few minutes, and gray, tephra-laden columns of water being ejected 20-30 m above the ocean’s surface. A satellite image on 4 August showed a small rounded gray zone at the water surface and a plume of discolored water drifting NE.

Report for Ebeko
KVERT reported that moderate activity at Ebeko was ongoing during 28 July-4 August. According to volcanologists in Severo-Kurilsk (Paramushir Island, about 7 km E) explosions generated ash plumes that rose up to 4.5 km (14,800 ft) a.s.l. and drifted in multiple directions. A thermal anomaly over the volcano was identified in satellite images during 1 and 3-4 August. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Report for Karymsky
KVERT reported that the eruption at Karymsky continued during 29 July-4 August. Explosions during 29-31 July, 1-2 August, and 4 August produced ash plumes that rose 4-8 km (13,100-26,200 ft) a.s.l. and drifted 230 km S, SE, and E. A thermal anomaly over the volcano was identified in satellite images during 31 July-4 August. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Report for Sheveluch
KVERT reported that the ongoing eruption at Sheveluch was characterized by explosions, hot avalanches, and lava-dome extrusion during 29 July-4 August. A daily thermal anomaly was identified in satellite images, and ash plumes were visible drifting 24 km SW on 31 July. The Aviation Color Code remained at Orange (the second highest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Report for Great Sitkin
AVO reported that slow lava effusion at Great Sitkin likely continued during 2-9 August; no changes to the flow lengths were visible but the lava had deepened around the vent. Weather clouds often obscured satellite and webcam views during most of the week, though no activity was visible when views were clear. Seismicity was low and occasional local earthquakes were recorded. Elevated surface temperatures were identified in satellite images during 5-9 August. The Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Report for Pavlof
AVO reported that a minor eruption at a vent on Pavlof’s upper E flank was ongoing during 3-9 August. Seismic tremor persisted and multiple daily explosions were detected in local and regional seismic and infrasound data. The explosions likely produced minor ash emissions that rose no higher than 3 km (10,000 ft) a.s.l., though cloud cover prevented confirmation on most days. Strongly elevated surface temperatures were identified in satellite images during 7-8 August. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Report for Kilauea
HVO reported that lava continued to effuse from a vent in the lower W wall of Kilauea’s Halema`uma`u Crater during 2-9 August, entering the lava lake and flowing onto the crater floor. The lake level remained within the bounding levees. Daily minor ooze-outs were visible along the margins of the crater floor. Intense incandescence from the W vent was visible during 5-9 August. Aviation Color Code and the Volcano Alert Level remained at Orange and Watch, respectively.

Report for Santa Maria
INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 2-9 August. Lava flows continued to advance in the San Isidro and El Tambor drainages on the W and SW flanks and were as long as 3.7 km by 5 August. Block avalanches from the W part of Caliente cone, and from both the ends and sides of the flows descended the S, SW, and W flanks. The avalanches generated ash plumes that rose about 1 km and drifted SW, S, and E, causing ashfall in areas downwind including La Florida, Monte Claro, San Marcos Palajunoj, Loma Linda, and Las Marías. Incandescence from Caliente cone and the lava-flow fronts was sometimes visible at night.

Report for Fuego
INSIVUMEH reported that 3-10 explosions per hour were recorded at Fuego during 2-9 August, generating ash plumes that rose as high as 1.1 km above the crater rim. The ash plumes drifted as far as 30 km W and SW, causing daily ashfall in areas downwind including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), Los Yucales (12 km SW), Sangre de Cristo (8 km WSW), El Porvenir (8 km ENE), San Pedro Yepocapa (8 km NW), Ojo de Agua, and Finca Palo Verde. Daily shock waves rattled structures in communities around the volcano and rumbling was occasionally heard. Daily block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), Honda, and Las Lajas (SE) drainages. Explosions ejected incandescent material 100-300 m above the summit each day.

Report for Nevado del Ruiz
On 2 August Servicio Geológico Colombiano’s (SGC) reported that during the previous week the number and size of seismic signals indicating fluid movement had increased at Nevado del Ruiz compared to the week before, though they remained at moderate levels. Although seismic signals indicating rock fracturing increased in number, magnitudes were similar to the previous week. Several episodes of drumbeat seismicity were recorded, indicating continuing growth of the lava dome. Gas-and-steam emissions rose from the crater, reaching just over 2.4 km above the summit on 30 July. Several thermal anomalies in Arenas Crater were identified in satellite images during 0500-0600 on 4 August, and seismic signals indicating emissions were recorded during 4-5 August. Ashfall was reported in the municipalities of Santa Rosa de Cabal, Pereira, Villamaría, Manizales, and Dosquebradas. Tephra deposits were visible near the crater and in areas up to 3 km away. The Alert Level remained at 3 (Yellow; the second lowest level on a four-color scale).

Report for Sabancaya
Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 1-7 August with a daily average of 19 explosions. Gas-and-ash plumes rose as high as 2.7 km above the summit and drifted E, SE, SW, and W. As many as seven thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Minor inflation continued to be detected near Hualca Hualca (4 km N). The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12-km radius.

Report for Krysuvik-Trolladyngja
The fissure eruption of the Krýsuvík-Trölladyngja volcanic system that began at around 1318 on 3 August continued at least through 9 August. Numerous small lava fountains rose along the fissure, located near the border of the previous flow field N of Fagradalsfjall, and lava flows traveled downslope to the NW. Scientists from the Institute of Earth Sciences stated that the initial flow rate was 5-10 times greater than the flow rate at the start of the 2021 eruption, based on model estimates, field data, and satellite measurements. The flow rate was about 32 cubic meters per second during the initial hours of the eruption, then decreased to an average of 18 cubic meters per second from 1700 on 3 August until 1100 on 4 August, by which time about 1.6 million cubic meters of lava had covered an area of 0.14 square kilometers. The average flow thickness was around 11 m. According to a news article the length of the active fissure had decreased and the middle part of the fissure was the most active. On 5 August Icelandic Meteorological Office (IMO) reported that the number of daily earthquakes declined after the eruption began and deformation stabilized. Thousands of people were walking on the trails to view the eruption; authorities warned the public to heed inclement weather warnings, and closed access to the site during 7-9 August due to weather conditions and trail maintenance.

Report for Grimsvotn
The Icelandic Meteorological Office (IMO) reported that seismicity at Grímsvötn had declined to normal levels during the past few days, and no significant variations from background levels were observed in geochemical or deformation data. On 9 August the Aviation Color Code was lowered to Green.