Volcanos

Roundup of Global Volcanic Activity – New Activity for the week 14 September – 20 September 2022

Alaid – Kuril Islands (Russia) : KVERT reported that an intense thermal anomaly over Alaid identified in satellite images beginning at 1139 on 15 September (local time) likely indicated the onset of a Strombolian eruption. The Aviation Color Code was raised to Yellow (the second lowest level on a four-color scale) the next day. Satellite images acquired at 1108 on 18 September showed a gas-and-steam plume containing ash drifting ESE. Several photographs of the eruption were taken that same day.

Home Reef – Tonga Ridge : The Tonga Geological Services reported that the new island at Home Reef that emerged from the ocean on 10 September continued to grow through 20 September. The eruption continued at variable intensities, producing daily plumes of gas and steam that rose no higher than 1 km above sea level. The island was surrounded by plumes of discolored water. The island was 170 m in diameter by 16 September and had grown to 182 m N-S and 173 m E-W by 18 September. Steam plumes with some ash content rose 3 km during 19-20 September. Mariners were advised to stay 4 km away from the volcano.

Piton de la Fournaise – Reunion Island (France) : OVPF reported that a seismic crisis at Piton de la Fournaise began at 0623 on 19 September. Volcanic tremor located beneath the SSW part of the caldera began at 0748, likely signifying the arrival of magma at the surface, though weather clouds prevented visual confirmation from webcams. Pelotons de Gendarmerie de Haute Montagne (PGHM) teams that were on-site to evacuate people from inside the caldera observed lava fountains 20-30 m high rising from a fissure that had opened E of Piton Kala Pélé. The eruption was confined to the caldera. By 20 September lava fountaining had decreased and the focus of the eruption was at the lower part of the fissure. Sulfur dioxide emissions peaked at an estimated 8,000 tons per day at the beginning of the eruption and then decreased to about 2,300 tons per day during 20-21 September.

Taupo – North Island (New Zealand) : On 20 September GeoNet raised the Volcanic Alert Level for Taupo to 1 (the second lowest level on a six-level scale) reflecting “minor volcanic unrest” characterized by ongoing seismicity and inflation. Seismicity beneath Lake Taupo began increasing in May. Earthquakes occurred at a rate of about 30 per week but increased to about 40 per week in early September. A M 4.2 earthquake, the largest so far this year, was recorded on 10 September and felt by over 1,000 people. By 20 September over 700 earthquakes had been located with depths less than 30 km, though most ranged 4-13 km. The earthquake locations were in two clusters: a larger cluster beneath the central and E part of the lake, and a smaller cluster to the W centered just offshore from Karangahape. An area of deformation at Horomatangi Reef had been rising at a rate of 60 mm (plus or minus 20 mm) per year since May. The area of uplift corresponded to the main seismic swarm. The data suggested that the seismicity and deformation was caused by the movement of magma and hydrothermal fluids. GeoNet noted that unrest at calderas was common and may continue for months or years without resulting in an eruption; more significant unrest would be indicated by additional indicators of activity and substantial impacts on the local area. There have been 17 previous episodes of unrest at Taupo over the previous 150 years, some more notable than the current episode, and many others before written records. None resulted in an eruption, with the last eruption occurring around 232 CE.

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