Volcanos

Roundup of Global Volcanic Activity

Etna (Sicily, Italy): The second paroxysm from the Voragine summit crater ended gradually during the course of today. Bad weather prevented detailed observations for most of the time. At the moment, the lava flow from the new vent at the eastern base of the North-East crater is still visible, but effusion has either stopped or strongly decreased.

Alaid (Northern Kuriles): Over the past week, activity of the volcano seems to have been declining. The satellite-based observation of heat output has been decreasing, suggesting that the eruption might be waning or ending. From 11-17 May 2016, the eruption of Alaid continued during 6-13 May. Satellite images showed an intense daily thermal anomaly over the volcano and a lava flow on the SW flank. The Aviation Color Code remained at Orange (the second highest level on a four-color scale).

Chirpoi (Kurile Islands, Russia): A weak thermal anomaly over Snow, a volcano of Chirpoi, was detected in satellite images during 9-11 and 14 May. The Aviation Color Code remained at Yellow.

Sakurajima (Kyushu, Japan): In the past days, the volcano has been back to its typical activity of intermittent, but often strong vulcanian-type explosions at irregular intervals between several days or only few hours with almost no visible activity in between. During 15-18 May, 9 explosions with ash plumes up to 15,000 ft altitude were recorded. No explosion has occurred during the past 48 hours, though. JMA reported that an explosion at the Minamidake summit crater (at Aira Caldera’s Sakurajima volcano) generated an ash plume that rose 3.7 km above the crater rim.

Ruapehu (North Island): On 17 May GeoNet reported that the lake temperature of Ruapehu's summit Crater Lake had decreased from a high of 46 degrees Celsius to 39 degrees, with some of the decrease attributed to rain and snowfall. Moderate levels of volcanic tremor continued, and analysis of water samples collected the previous week showed no changes in the lake chemistry. During recent visits, scientists measured a larger output of volcanic gases. The Volcanic Alert Level remained at 2 (moderate to heightened unrest) and the Aviation Colour Code remained at Yellow.

Cleveland (Aleutian Islands, Alaska): After the small explosions at the volcano on 5 and 10 May, no further unusual activity has been noted on satellite and seismic data until 14 May. The Alaska Volcano Observatory detected "energetic steaming and highly elevated surface temperatures in the summit crater" on 15 May. The Level of Concern Color Code remained at Orange and the Volcano Alert Level remained at Watch." (AVO)

Colima (Western Mexico): The activity of the volcano has remained essentially unchanged over the past months and is currently relatively low. Growth of a small lava dome continues in the summit crater (as indicated by some glow at night) and small to moderate explosions occur at rates of a few per day. Ash plumes have been reaching 1-4 km height above the crater during the recent week.

Fuego (Guatemala): A relatively large pyroclastic flow (avalanche of hot debris and ash) descended from the volcano yesterday (18 May) morning at around 10:30 local time. The unusual aspect is that it occurred during a phase of currently low activity with no active lava flow or intense explosive activity (as during the paroxysms). There seemed not to have been any precursor signs either. The most likely cause should be a collapse of accumulated, unstable material from previous eruptions on the upper slopes, something that would not be too unusual to happen.

Nevado del Ruiz (Colombia): The Manizales volcano observatory reported that sporadic mild ash emissions continue to occur at the volcano, last on 17 and 18 May. During 10-16 May seismicity at Nevado del Ruiz was characterized by long-period and very-long-period earthquakes, episodes of continuous tremor, and pulses of volcanic tremor associated with gas-and-ash emissions. Thermal anomalies near Arenas Crater were identified in satellite images during 11-12 May. Significant amounts of water vapour and gas rose from the crater during the week. A gas, steam, and ash plume rose 1.7 km and drifted NW and W on 12 May.

Sangay (Ecuador): The mild eruption that had started in early March continues with no significant changes. According to IGEPN, the number of tremor events and long-period earthquakes were slightly higher in March as compared to the number recorded in April and May, and the number of explosions was slightly higher in April and May. Surficial activity was characterized by frequent ash emissions generated by explosive activity. Thermal anomalies on the flanks were also detected, mostly within 5 km of the summit crater, which possibly corresponded to short-range pyroclastic flows and lava flows. No abnormal sulfur dioxide emission were detected.

Cotopaxi (Ecuador): During an overflight of Cotopaxi on 10 May, scientists observed minor gas emissions rising 600 m above the crater and drifting N and NW. Glaciers remained cracked, though glacial melting observed in recent months had decreased considerably. The temperature of flank fumaroles had decreased slightly.