Volcanos

Global Volcanic Activity - New Activity for the week of 17 July - 23 July 2019

Manam | Papua New Guinea : The Darwin VAAC reported that on 21 July an ash plume from Manam rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted SW and W, based on satellite data and weather models.

Semisopochnoi | United States : AVO reported that data from local seismic and infrasound sensors likely detected a small explosion at Semisopochnoi on 16 July. No ash was visible in cloudy satellite images although none was expected from an explosion of its size. A small plume drifted 18 km from the vent but had no indication of ash. A strong tremor signal was recorded at 2339 on 17 July and an infrasound signal was detected from an array located 260 km E on Adak Island. The event likely produced ash emissions, though none were visible above the cloud deck at 3 km (10,000 ft) a.s.l. Seismic activity continued to increase. On 18 July a short-lived, low-level eruption prompted AVO to raise the Aviation colour Code to Orange (the second highest level on a four-colour scale) and the Volcano Alert Level to Watch (the second highest level on a four-level scale). A low-level plume was visible in occasional cloud-free satellite images. Seismic activity decreased abruptly that night and ground-coupled airwaves stopped being detected on adjacent islands, suggesting that the eruption had paused or ended. Seismic activity remained low at least through 21 July.

Shishaldin | Fox Islands (USA) : AVO reported that weak tremor continued to be recorded at Shishaldin during 17-23 July and elevated surface temperatures were observed in multiple satellite images. Cloudy conditions typically obscured webcam views of the volcano, but when conditions were clear a small steam plume at the summit was visible. The Aviation colour Code remained at Yellow and the Volcano Alert Level remained at Advisory.

Stromboli | Aeolian Islands (Italy) : INGV reported that multiple vents on Stromboli’s crater terrace were active during 15-21 July, though the exact number was unknown due to the unfavorable positions of the cameras. Vents in Area N (north crater area, NCA) produced low-to-medium-intensity explosions at a rate of 4-10 events per hour, ejecting lapilli and bombs less than 150 m high. The vents of Area C-S (South Central crater area) generated explosions of intensities variable between low and very high and at a rate of 6-17 events per hour. Tephra was ejected over 200 m high. Lava from Area C-S vents continued to travel down the S part of the Sciara del Fuoco shedding blocks that rolled all the way to the coastline.

Ubinas | Peru : IGP reported that during 17-19 July gas-and-ash emissions occasionally rose from Ubinas’s summit crater and drifted N, E, and SE. Beginning at 0227 on 19 July as many as three explosions (two were recorded at 0227 and 0235) generated ash plumes that rose to 5.8 km above the crater rim. The Buenos Aires VAAC reported that ash plumes rose as high as 6.5 km above the crater rim (or to 40,000 ft. a.s.l.) based on satellite images. The Alert Level was raised to Orange (on a 4-level scale). Ash plumes drifted as far as 250 km E and SE, reaching Bolivia. Ashfall was reported in areas downwind including the towns of Ubinas (6.5 km SSE), Escacha, Anascapa (11 km SE), Tonohaya (7 km SSE), Sacohaya, San Miguel (10 km SE), Huarina, and Matalaque, causing some families to evacuate. The VAAC reported that during 20-23 July ash plumes rose to 7.3-9.5 km (24,000-31,000 ft) a.s.l. and drifted E, ESE, and SE.