Volcanos

Roundup of Global Volcanic Activity – New Activity for the week 6 April – 12 April 2022

Bezymianny – Central Kamchatka (Russia) : KVERT reported that a daily thermal anomaly over Bezymianny was visible in satellite images during 2-8 April. Strong fumarolic activity, incandescence at the lava dome, and avalanches were also reported.

Poas – Costa Rica : OVSICORI-UNA reported that on 6 April at 0240 a phreatic explosion from a vent called “Orange Fumarola” located in a fumarolic field along the inner N crater wall at Poás generated a plume that rose 500 m above the crater rim. Activity lasted for three minutes. The event caused a small landslide that modified the vent. Some of the material from the landslide was deposited in a narrow strip about 100 m into the Boca A lake. Stirred sediment was visibly moving in convection cells, turning the lake water from green to a uniform milky gray color as the sediment mixed into the water. Subaerial fumarolic vents at the E and S parts of the lake more vigorously emitted gasses following the event and remained at that level at least through 12 April. Convection in the lake also continued. OVSICORI-UNA noted that satellite data acquired the day before the explosion showed a total of 500 tons of sulfur dioxide released from both Poás and Turrialba.

Purace – Colombia : On 29 March Observatorio Vulcanológico y Sismológico de Popayán, Servicio Geologico Colombiano (SGC), reported that the number of earthquakes at Puracé had increased during the previous few weeks, and were characterized by volcano-tectonic (VT) events, indicating rock fracturing, and long-period (LP) and volcanic tremor (TR) events, indicating fluid movement. The number of events notably increased on 28 March, with 479 VT, 183 (LP), and 119 (TR) events in total. The magnitudes of events abruptly increased the next day; the largest event was a M 3.3 recorded at 1214 on 29 March. Two fractures opened on 29 March, each about 40 m long, and produced gas emissions detected by satellite; ash was reported by observers in the area. The fractures were located along Coconucos Volcanic Chain, between Puracé Volcano and Curiquinga Volcano. The Alert Level was raised to Yellow (the second lowest on a four-color scale) on 30 March. Seismicity continued to be elevated through 4 April. The earthquakes were low magnitude, and located about 800 m SE of Puracé and beneath Curiquinga, at depths of 2 km on average. The number of events signifying fluid movement was increasing. GNSS (Global Navigation Satellite System) geodetic network and DInSAR (Differential Interferometry by Synthetic Aperture Radar) showed inflation on the millimeter scale. Sulfur dioxide and carbon dioxide emissions increased, based on satellite and ground-based sampling data, and a fumarole on the N flank of Puracé intensified and produced a strong sulfur odor. Significant unrest continued during 5-11 April. The seismic network recorded a total of 2,077 earthquakes, consisting of 248 VT events, 1,759 LP events, 37 low-energy TR events, and 31 hybrid events. Millimeter-scale inflation persisted, and sulfur dioxide emissions averaged 1,800 tonnes per day.

Ruapehu – North Island (New Zealand) : On 12 April GeoNet reported that unrest at Ruapehu had intensified during the previous week, characterized by increased gas emissions, elevated tremor, and increasing crater lake water temperatures. Tremor levels were elevated but had declined from the peak reached during 6-7 April. Higher levels of gas emissions were confirmed during an overflight on 11 April; a peak carbon dioxide value was the second highest ever recorded at Ruapehu. Lake temperatures continued to slowly climb and reached 38 degrees Celsius. The lake water was gray in color and had area of upwelling over the N vents; sulfur slicks on the lake’s surface were visible. GeoNet noted that temperature and modeled heat input to the lake were within typical ranges for a heating cycle, though the elevated tremor levels and gas emissions suggested that magma was interacting with the geothermal system.

Taal – Luzon (Philippines) : PHIVOLCS lowered the Alert Level for Taal to 2 (on a scale of 0-5) on 9 April, noting a significant decrease in activity during the previous two weeks. Sulfur dioxide emissions were high during the first three weeks of March, peaking at 21,211 tonnes per day on 16 March, but dropped on 3 April to an average of 240 tonnes per day; the flux again decreased to 103 tonnes per day on 8 April, the lowest number recorded since unrest began in 2021. During 26 March-9 April only 86 small-magnitude and imperceptible volcanic earthquakes had been recorded, and by 31 March background tremor associated with shallow hydrothermal activity had ceased. Electronic tilt monitoring on Taal Volcano Island, continuous Global Positioning System (GPS) data, and InSAR analysis of Sentinel-1 satellite data indicated continuing deflation of Taal, particularly on the SE flank. Diffuse plumes from the lake had also decreased in frequency, though they rose 600-900 m above the surface during 10-12 April. Sulfur dioxide emissions were below instrumental detection limits on 11 April.

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