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.

According to the Tokyo Volcanic Ash Advisory Center (VAAC) a possible eruption at the Ivao Group may have generated an ash plume that rose 2.7 km (9,000 ft) a.s.l. and drifted E at 2150 on 29 May. Any ash had dissipated by 0120 on 30 May.

Source: Tokyo Volcanic Ash Advisory Center (VAAC)

The Rabaul Volcano Observatory (RVO) reported that the eruption at Titan Ridge continued during 28 May-4 June. After a decrease in activity over a couple of days the number of hydroacoustic signals significantly increased during 28-29 May, signifying the resumption of semi-continuous activity. Weather clouds prevented satellite observations of the vent areas. Activity was ongoing during 29 May-2 June based on satellite views and hydroacoustic data. By 1 June a steam plume was rising from part of the NE vent area and drifting E and SE; there were no plumes rising from the vent area to the SW. A shallow plume of discolored water drifted as far as 8 km SE from the NE vent. Hot pumice associated with the plume of discolored water was seen floating within a few hundred meters of the vent area; resultant thermal anomalies were hotter than those previously detected. Pumice rafts from previous days were scattered around the Bismarck Sea. During 2-4 June the eruption plume rose as high as 5 km a.s.l. The steam-and-gas plume as well as a plume of discolored sea water drifted NW, N, E, and SE. The number of daily hydroacoustic signals declined on 3 June. Significant amounts of floating pumice, thick and extensive rafts, washed up on the shores of the Admiralty Islands.

Source: Rabaul Volcano Observatory (RVO)

The Japan Meteorological Agency (JMA) reported increasing seismicity at Tokachidake. Fumarolic activity, including the volume of plumes and the rate of volcanic gas emissions at Crater 62-2, remained high. Seismicity began gradually increasing in April, with occasional temporary spikes in earthquake frequency; volcanic activity overall showed a slight upward trend. The number of volcanic earthquakes located at shallow depths beneath Crater 62-2 began to increase at around 0100 on 31 May and by 0900 on 1 June the network had recorded a preliminary total of 86 events. The Alert Level remained at 1 (on a 5-level scale).

Source: Japan Meteorological Agency (JMA)

The Japan Meteorological Agency (JMA) reported ongoing eruptive activity at Minamidake Crater (Aira Caldera?s Sakurajima volcano) during 25 May-1 June. Very small eruptive events were detected during 25-29 May. Crater incandescence was visible in nighttime webcam images during 29 May-1 June. Eruptive events at 1917 on 29 May, at 0443, at 1954, and at 2223 on 30 May, and at 1510 on 31 May generated ash plumes that rose 1.1-1.3 km above the crater rim and drifted in multiple directions. 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-and-gas plumes from Ambae were identified in satellite and/or webcam images and seen by local observers during 28-29 May and 3 June; plumes rose to 1.2-3 km (4,000-10,000 ft) a.s.l. and drifted SW, E, NW. 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 28 May-3 June. Daily white-to-gray or gray-to-black plumes rose 200-1,300 m above the summit and drifted NE, E, and SE. Faint rumbling was heard at the Dukono observation post (11 km N) on 31 May. 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 28 May-3 June. Radar data acquired on 29 May confirmed that slow growth was concentrated along the E margin. Minor seismicity was detected on most days. Weather clouds sometimes prevented webcam and satellite observations, though slightly elevated surface temperatures were visible in satellite images during 29 May-2 June. 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 28 May-3 June, with daily eruptive events recorded by the seismic network. Daily gray or white-to-gray ash plumes rose 300-800 m above the summit and drifted NE and NW. Incandescence at the summit was visible in some nighttime webcam images. 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 28 May-3 June. The seismic network recorded 7-24 daily volcanic earthquakes, including 0-12 daily periods of volcanic tremor lasting 3 minutes to six hours and 13 minutes each. Sulfur dioxide emissions ranged from 1,201 to 2,428 tonnes per day during 28-30 May. Volcanic emissions rose as high as 1.5 km above the summit and drifted SW, SE, and E; weather conditions obscured views on 31 May. During 28-30 May and 3 June there were 1-7 daily periods of ash emissions lasting as short as three minutes to as long as one hour and 51 minutes. Specifically, the webcam recorded grayish ash emissions at 0600 on 28 May rising 1.2 km above the crater rim and drifting SW. 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)

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 20-27 May. Nighttime incandescence was persistent at both the N and S vents during 27-30 May. Two brief small bursts of spatter at the N vent occurred on 27 May; spattering became sporadic by the evening of 28 May and more vigorous by 0751 on 31 May, building a small cone around the vent. A single spatter burst at the S vent occurred at 0347 on 29 May. Lava overflowed the S vent at 1741 on 30 May, prompting HVO to raise the Volcano Alert Level to Watch (the second highest level on a four-level scale) and the Aviation Color Code to Orange (the second highest color on a four-color scale) at 1749. There were 94 more overflows at the S vent through the morning of 1 June, produced by low dome fountains. Each overflow occurred every 15-30 minutes and lasted 5-10 minutes. The sluggish lava flows traveled short distances (a few hundred meters) from the vent. A lava overflow occurred at the N vent at 0346 on 1 June. Low-level dome fountaining steadily escalating in vigor and height until it transitioned to sustained lava fountaining at 0440. The fountains grew to a maximum height of around 200 m at 0550. The lava fountain produced significant heat and ash, feeding an eruption plume that rose as high as 7.6 km (25,000 ft) a.s.l. based on radar data reported by the National Weather Service (NWS) and Washington Volcanic Ash Advisory Center. Initially, lower-level trade winds from the NE caused most tephra to be deposited in areas SW of Halema?uma?u. Parts of the plume at higher altitudes 3-6.1 km (10,000-20,000 ft) a.s.l. drifted N. Tephra fell at several locations around the rim of Kaluapele. At 0531 the NWS issued an ashfall advisory for the SE and NE parts of the island, including Hawai?i Volcanoes National Park. Pumice up to 2-5 cm in diameter fell at the Uekahuna overlook and Namakanipaio campground along with Highway 11 W to the 34-mile marker. Fine ash and Pele?s hair were deposited around the Kilauea Visitor Center and outside of the national park in communities to the NE, including Mauna Loa Estates, Ohia Estates, and Volcano village as well as to the W of the caldera between the 34- and 36-mile markers. Very sparse, fine ash was reported as far as Mountain View. A commercial pilot reported and ash-and-gas cloud off of Laupahoehoe. According to a news article, flights between Hilo and Honolulu were cancelled after ash fell on the runway. After reaching the maximum height, the lava fountain gradually declined over a few hours and was 90 m tall by around 1237. Continuous fountaining ended after 9 hours at 1337, with gas jetting occurring during the last minute. The average effusion rate was 185 cubic meters per second; the highest peak was 320 cubic meters per second, occurring just before 0600. An estimated 7.3 million cubic meters of lava erupted and covered about 40 percent of the Halema?uma?u Crater floor. Gas jetting and spattering from the S vent was periodically visible during the fountaining episode at the N vent. At 1347 the Volcano Alert Level was lowered to Advisory and the Aviation Color Code was lowered to Yellow. During 1-2 June flames at the vents were periodically visible, as well as continuous incandescence throughout the night. The current Halema?uma?u eruption now has the most fountaining episodes ever recorded for an eruption, with more than the 47 episodes of the Pu?u ?O?o eruption. Though other eruptions have had additional episodes related to changes in vent activity and location, this count only applies to episodic fountains.

Sources: Hawaii News Now ,US Geological Survey Hawaiian Volcano Observatory (HVO)

The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported ongoing eruptive activity at Lewotolok during 28 May-3 June. Daily white plumes rose as high as 100 m above the summit and drifted in multiple directions. An eruptive event at 2317 on 28 May generated a white-and-gray plume that rose 100 m above the summit and drifted SE. A webcam image at 2318 that same day showed incandescent material on the cone?s flanks. On 30 May white-and-gray plumes rose up to 200 m above the summit. Incandescent material on the cone?s flanks was visible in a webcam image from 2318 later that day. Minor incandescence at the summit was visible in a webcam image from 2333 on 1 June. 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.

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 Marapi (on Sumatra) continued during 28 May-3 June. At 0842 on 30 May a dense gray ash plume rose to around 2 km above the summit and drifted NE. Eruptive events were recorded at 1956 on 2 June and at 0305 on 3 June but weather conditions prevented visual confirmation. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the active crater.

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