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 Wednesday, 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 Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a thermal anomaly over Bezymianny was identified in satellite images during 1-8 May. According to the Institute of Volcanology and Seismology (IVS) of the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS), crater incandescence was visible during dark hours on most days, though weather clouds mostly obscured views during 5-6 May. Hot avalanches of material descended the flanks during 1-3 May. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale). Dates are reported in UTC; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing unrest at Bulusan during 6-12 May. The seismic network recorded 18-124 daily volcanic earthquakes. Voluminous gas-and-steam emissions rose as high has 400 m above the summit and drifted NW, WNW, W, and WSW. Daily averages of sulfur dioxide emissions ranged from 466 to 1,117 tonnes per day; emissions were not reported on 11 May. A special advisory was issued on 12 May due to increasing seismicity. From 0000 on 8 May until 1330 on 12 May the seismic network recorded 309 volcanic earthquakes; of those 287 were volcano-tectonic earthquakes indicating rock fracturing at shallow depths (less than 4 km) beneath the SE flank and 22 were low-frequency earthquakes associated with fluid movement. The Alert Level remained at 1 (the second lowest level on a scale of 0-5). The public was reminded not to enter the 4-km-radius Permanent Danger Zone (PDZ) and to be vigilant within the 2-km Extended Danger Zone (EDZ) on the SE flank.

Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS)

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported continuing eruptive activity at Kanlaon during 6-13 May. Daily sulfur dioxide emissions ranged from 554 to 3,055 tonnes per day. Gas-and-steam plumes with occasional ash content rose as high as 1 km above the crater rim and drifted NW, W, SW, and SE. Periods of ash emissions were noted on 8 May (5 minutes) and 11 May (27 minutes). The seismic network recorded 5-10 daily volcanic earthquakes during 6-10 May and 63 volcanic earthquakes on 11 May. A total of 135 volcanic earthquakes were detected by the seismic network from 0000 on 11 May to 1200 on 12 May, including relatively strong volcanic-tectonic earthquakes, indicating rock fracturing due to rising magma or gases. A total of 72 volcanic earthquakes (M 0.3-3.1) recorded during 0000-1200 on 12 May were located 0-8 km beneath the N and NW flanks. PHIVOLCS issued an advisory at 1330 on 12 May noting increased seismicity. A moderately explosive eruption began at 0255 on 13 May and lasted for five minutes based on seismic and infrasound data. Audible rumbling sounds were heard in barangays in Negros Oriental, including Pula and Canlaon City (10 km ESE), and in La Castellana (16 km SW) in Negros Occidental. A voluminous grayish ash plume rose about 4.5 km above the summit and drifted SW. Incandescent pyroclastic density currents descended the S flanks as far as 2 km based on visual and thermal camera monitoring. Large fragments were ejected from the crater a few hundred meters and set vegetation near the summit on fire. Minor ashfall was reported in the barangays of Yubo and Ara-al (La Carlota City, 14 km W), in Ilijan and Binubuhan (Bago City, 30 km NW), and in Biak-na-Bato, Sag-ang, and Mansalanao (La Castellana). According to news articles additional reports of ashfall came from San Carlos City (31 km ENE) and Bacolod (35 km NW), as well from the municipalities of Murcia (24 km NW), San Enrique (29 km W), Valladolid (34 km W), Pontevedra (29 km WSW), Hinigaran (35 km SW), and Binalbagan (38 km SW). A sulfur odor was also reported in several localities. According to the Tokyo VAAC the ash plume rose to 7.9 km (26,000 ft) a.s.l., or 5.5 km above the summit. Dozens of flights in and out of the affected areas were cancelled, and others delayed or rerouted, during 13-14 May. The Alert Level remained at 3 (on a scale of 0-5); the public was warned to stay 6 km away from the summit and pilots were warned not to fly close to the volcano.

Sources: Air Asia,Cebu Pacific,Philippine Airlines,Philippine Institute of Volcanology and Seismology (PHIVOLCS) ,Philippine News Agency (PNA) ,Tokyo Volcanic Ash Advisory Center (VAAC)

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that a thermal anomaly at Klyuchevskoy was identified in satellite images during 1, 4, and 6-8 May. The Aviation Color Code remained at Yellow (the second lowest level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that at 0509 on 9 May an ash plume rose around 1 km above Raung?s summit crater rim and drifted N and NW. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

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

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity at Dukono continued during 7-13 May. Daily gas-and-ash plumes rose 100-1,500 m above the summit and drifted E, SE, and S. 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 Sezione di Catania - Osservatorio Etneo (INGV) reported continuing eruptive activity at Etna?s SE Crater and gas emissions at Bocca Nuova Crater, NE Crater, and Voragine during 5-11 May. Strombolian activity at SE Crater began in the late morning of 5 May, though weather clouds obscured visual observations. An eruption cloud drifted downwind and caused minor ashfall along the ENE flank reaching the town of Fiumefreddo di Sicilia, 19 km ENE. Two small lava flows descend the flank of SE Crater with the shorter flow to the S.

Source: Sezione di Catania - Osservatorio Etneo (INGV)

The Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported continued eruptive activity at Fuego during 6-13 May. Daily explosions were recorded by the seismic network at rates of 1-8 per hour. Incandescent material was observed at night being ejected 100-300 m above the summit. The explosions generated gas-and-ash plumes that rose as high as 1.1 km above the summit and drifted as far as 30 km W and SW. Rumbling sounds and shock waves were occasionally reported. Explosions sometimes generated block avalanches around the crater that descended the Santa Teresa (W) and Ceniza (SSW) drainages. Ashfall was reported in Panimache I and II (8 km SW), Morelia (10 km SW), Santa Sofia (12 km SW), El Porvenir (11 km SW), Finca la Asunción (12 km SW), and surrounding areas on a few of the days. During the afternoon of 10 May a lahar descended the Ceniza drainage, carrying tree branches, trunks, and blocks as large as 3 m in diameter.

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

The Alaska Volcano Observatory (AVO) reported that slow lava effusion continued to feed a thick flow in Great Sitkin?s summit crater during 7-13 May. Small daily earthquakes were detected by the seismic network. No unusual activity was observed in satellite and webcam views, though weather clouds often obscured views of the volcano. 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 Tonga Geological Services reported continuing activity at Home Reef during 3-11 May. Moderate thermal anomalies were detected by the Middle InfraRed Observation of Volcanic Activity (MIROVA) system only on 4 May, though persistent weather clouds hindered observations. Infrasound instruments did not detect any signals. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-level scale, the Maritime Alert Level remained at Orange (the third level on a four-level scale) with advice to stay at least 2 nautical miles (3.7 km) from the island, and the Alert Level for residents of Vava?u and Ha?apai remained at Green (the first level on a four-level scale).

Source: Tonga Geological Services, Government of Tonga

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that the eruption at Ibu continued during 7-13 May. Daily gray, white-to-gray, or white-to-brown ash plumes rose 300-800 m above the summit and drifted in various directions. Nighttime crater incandescence was visible in some webcam images. The Alert Level remained at 3 (the second highest level on a four-level scale) and the public was advised to stay 4 km away from the active crater and 5 km away from the N crater wall opening.

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

The Kamchatkan Volcanic Eruption Response Team (KVERT) reported that thermal anomalies over Karymsky were identified in satellite images during 1-3 and 7 May. Ash clouds drifted 25 km E on 1 May. The Aviation Color Code remained at Orange (the third level on a four-color scale). Dates are based on UTC times; specific events are in local time where noted.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)