INGEOMINAS reported that during 31 July-6 August the magnitude and occurrence of earthquakes detected at Galeras had increased since the previous week. Gas plumes sometimes containing tephra rose from the crater. Observatory staff working near the crater reported a strong sulfur odor on 1 and 6 August. On 3 August a steam plume rose 1.1 km above the crater. On 4 August ash emissions were observed in the morning, and at 1519 a seven-minute-long episode of tremor was accompanied by a gas-and-ash plume that rose 1.4 km above the crater and drifted N. Ashfall was reported in Genoy, 6 km NE. An ash plume rose from the crater on 7 August. The Alert Level remained at III (Yellow; "changes in the behavior of volcanic activity").

Source: Servicio Geológico Colombiano (SGC)

On 6 August GeoNet reported that volcanic earthquakes continued beneath Tongariro but the size and number had decreased; there were fewer than five events each day. At about 2350 a short-lived (~1-2 minutes) phreatic eruption occurred at the Te Mari craters area, followed by a series of discrete small earthquakes over the next few tens of minutes. The Alert Level was raised to 2 (on a scale of 0-5) and the Aviation Colour Code was raised to Orange (second highest on a four-color scale). An ash plume drifted E and ashfall was reported in areas around the volcano. According to a news article, a GNS Science volcanologist noted that there were reports of "red hot rocks being thrown out of the crater", explosions, and lighting. The article also stated that some people in the Tongariro area had self-evacuated following the eruption. The Desert Road section of State Highway 1 (NE) had been closed due to poor visibility from the ash, and about 5 cm of ash had fallen on State Highway 46, to the N. Some flights to and from Gisborne (210 km ENE), Rotorua (120 NNE), Taupo (60 km NE), and Palmerston North (135 km S) were delayed or cancelled due to the eruption, and Hawke's Bay Airport (110 km ESE) had closed. GeoNet observed that no volcanic tremor occurred in the days preceding the eruption. The last eruption occurred in 1897. [Correction: The last eruption from the Te Mari craters area had occurred in 1896.]

On 7 August white steam clouds rose from the Te Mari craters area but poor weather conditions at the time obscured a direct view of the active vent(s). A few small earthquakes had been detected. A news article stated that alpine guides observed three active vents that appeared to be new.

Sources: Stuff, GeoNet

The GeoNet Data Centre reported that during 2011 and early 2012 White Island Crater Lake slowly evaporated, exposed steam vents, and formed two large muddy pools. Sometime between 27 July and 28 July, the lake level quickly rose 3-5 m. Vigorous gas-and-steam emissions through the new lake were observed from the air. Gas emission measurements on 1 August showed that sulfur dioxide had increased during the previous three months but carbon dioxide levels did not change.

Since early July there had been intermittent periods of volcanic tremor, including several hours early on 28 July and during 30-31 July. GeoNet noted that tremor was not uncommon at White Island but earlier in 2012 it had been at very low levels. A recent ground survey showed that the main crater floor was no longer subsiding and may have been slowly rising. The Alert Level remained at Level 1 (on a scale of 0-5), indicating signs of volcano unrest. The Aviation Colour Code increased to Yellow (second lowest on a four-color scale).

A particularly strong period of volcanic tremor was recorded during 4-5 August, and ended with an earthquake at 0454. Web camera images from between 0454 and 0457 showed an eruption from Crater Lake. This was the first time ash has been produced from White Island since 2000. [Correction: The last eruption occurred in 2001.] The Alert Level was raised to 2 and the Aviation Colour Code was raised to Orange. A steam plume rose from the crater on 5 August. Around 2330 on 7 August volcanic tremor sharply decreased to levels detected prior to the current episode of unrest. A few hours after this drop, the color of the plume changed from white to light brown, indicating more ash in the plume. Visual observations in the past few days showed that a small cone was building in the lake, around the main area of degassing.

Source: GeoNet

JMA reported that during 30 July-3 August three explosions from Sakura-jima's Showa Crater ejected tephra as far as 800 m from the crater. A small explosion from Minami-dake Crater occurred on 31 July. Based on information from JMA, the Tokyo VAAC reported that explosions during 1 and 3-7 July often produced plumes that rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted SW, W, and NW.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC), Japan Meteorological Agency (JMA)

Based on analyses of satellite imagery, the Darwin VAAC reported that on 2 August ash plumes from Bagana rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 37 km NW and W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

Based on analyses of satellite imagery, the Darwin Volcanic Ash Advisory Centre (VAAC) reported that during 1-2 and 4-7 August ash plumes from Batu Tara rose to altitudes of 1.8-2.1 km (6,000-7,000 ft) a.s.l. and drifted 37-65 km NW and W.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

AVO reported that cloud cover prevented satellite and web-camera observations of Cleveland during 1-3 and 5-6 August. A small explosion at 0838 on 4 August was detected based on retrospective analysis of infrasound data. Satellite images showed a brief, faint steam plume about four hours after the event and also detected elevated surface temperatures in several clear views of the volcano. On 7 August elevated surface temperatures were detected in partly-cloudy satellite images. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Source: US Geological Survey Alaska Volcano Observatory (AVO)

In a special bulletin on 3 August, INSIVUMEH reported a new phase of activity at Fuego, characterized by increased seismicity and degassing sounds. Incandescent tephra was ejected 200 m high and a lava flow traveled 500 m down the SW flank into the Taniluya drainage. Pyroclastic flows likely descended the SE and SW flanks. During 4-7 August explosions produced ash plumes that rose 200-400 m above the crater and drifted NW and W. Lava flows traveled 250-300 m down the Taniluyá drainage. Detached blocks from the lava-flow front traveled down the flanks to the vegetated area. Blocks also traveled down the Ceniza drainage (SSW). At night during 5-6 August explosions ejected incandescent tephra 100 m above the crater.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

KVERT reported moderate seismic activity from Karymsky during 27 July-3 August. Satellite imagery showed a weak thermal anomaly on the volcano on 31 July, and 2 and 6 August. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

During 1-7 August HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kīlauea's Halemaʻumaʻu Crater. Measurements indicated that the gas plume from the vent continued to deposit variable amounts of spatter and Pele's hair onto nearby areas. Glow from the lava pond in a small pit on the E edge of the Puʻu ʻŌʻō crater floor and two vents along the S edge of the floor was visible with the web cameras. Lava flows were active on the pali and the coastal plain.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)

According to INGEOMINAS, the Observatorio Vulcanológico and Sismológico de Manizales reported that during 3-6 August low levels of tremor were detected at Nevado del Ruiz, possibly associated with continuing gas and ash emissions. Ashfall and a strong sulfur odor were reported in Manizales (30 km NW) and in the municipality of Chinchiná (30 km WNW). Satellite images showed continuing sulfur dioxide emissions on 6 August. Web cameras near the volcano recorded a gas-and-steam plume rising 700 m that drifted SW on 8 August. The Alert Level remained at II (Orange; "eruption likely within days or weeks").

Source: Servicio Geológico Colombiano (SGC)

CENAPRED reported that during 1-7 August seismicity at Popocatépetl indicated continuing gas-and-steam emissions that may have contained ash during 4-6 August; cloud cover prevented observations during most of this period. Incandescence from the crater was periodically observed. Gas-and-steam plumes were observed almost daily rising from the crater as high as 2.5 km above the rim. The plumes drifted SW and NW. On 5 August ash plumes rose 1.5 km and drifted SW. On 6 August ash plumes again rose 1.5 km above the crater, and at 1758 an ash plume rose 4 km. Some explosions ejected incandescent tephra that landed on the flanks. Gas-and-steam plumes drifted SW the next day. The Alert Level remained at Yellow, Phase Three.

Source: Centro Nacional de Prevencion de Desastres (CENAPRED)

KVERT reported that during 27 July-6 August explosive activity was detected at Shiveluch; a strong explosion detected on 27 July possibly produced an ash plume that rose 10 km (32,800 ft) a.s.l. Satellite imagery showed a daily thermal anomaly on the lava dome. Observers noted gas-and-steam activity during 28-29 and 21 July. The Aviation Color Code remained at Orange.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

IG reported that during 1-5 August visual observations of Tungurahua were limited due to cloud cover. A small steam plume rose from the crater on 3 August and drifted W. Explosions on 5 August vibrated windows in nearby areas and produced sounds resembling gunshots. A plume rose 3 km above the crater and drifted W. Explosions during 5-6 August produced gas plumes with small amounts of ash that drifted WSW. Steam plumes rose 100 m above the crater the next day.

Source: Instituto Geofísico-Escuela Politécnica Nacional (IG-EPN)