Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 8 September – 14 September 2021

Askja – Iceland : On 9 September IMO raised the Aviation Color Code for Askja to Yellow, noting that inflation that began in early August was ongoing and notably rapid. The uplift was centered at the W edge of Oskjuvatn caldera, which rose a total of 7 cm. The data suggested that magma was accumulating at 2-3.5 km depth.

Fukutoku-Oka-no-Ba – Volcano Islands (Japan) : The Japan Coast Guard reported that during a 12 September overflight of Fukutoku-Oka-no-Ba, observers noted that the W island was unchanged while the E side had been completely eroded and submerged. Yellow-green to yellow-brown discolored water extended from the vent area to the SW, S, and SE, suggesting continuing eruptive activity. Another area of discolored water had an approximate diameter of 2 km and was about 2 km ENE of the volcano. The discolored water prompted JMA to issue a navigation warning to nearby vessels.

La Palma – Spain : Instituto Volcanológico de Canarias (INVOLCAN) reported that a seismic swarm beneath Cumbre Vieja at the S part of La Palma began at 1618 on 11 September and was likely associated with a magmatic intrusion. The swarm intensified in number of events and magnitude, and by 1600 on 12 September a total of 315 earthquakes had been recorded and ranged 8-13 km in depth. The largest event was a M 2.8 (on the Mb_lg scale). On 13 September a scientific committee comprised of representatives from multiple agencies and institutions raised the Alert Level to Yellow (the second lowest level on a four-color scale) for the municipalities of El Paso, Los Llanos de Aridane, Mazo, and Fuencaliente de la Palma. By 0800 on 14 September 2,935 earthquakes had been detected. Larger events were felt by residents during 13-14 September; the largest earthquake was a M 3.9, recorded at 0600 on 14 September. Overall, the events were becoming shallower (8-10 km) and hypocenters migrated slightly to the W. GPS and tiltmeter networks showed deformation totaling 1.5 cm centered over the clusters of epicenters. INVOLCAN noted that 10 seismic swarms have been detected at La Palma since 2017; one in 2017, one in 2018, five in 2020, and three in 2021. The earthquakes in the previous swarms were deeper, between 20 and 30 km, and were less intense than the current swarm.

Pagan – Mariana Islands (USA) : The U.S. Geological Survey reported that emissions of ash and sulfur dioxide from Pagan were last detected on 6 September, though robust steam plumes occasionally continued to be visible at least through 14 September.

Whakaari/White Island – North Island (New Zealand) : On 14 September GeoNet reported that intermittent ash emissions at Whakaari/White Island continued to be visible during the previous week. Vigorous fumarolic plumes from the active vent area sometimes carried minor amounts of ash downwind at low altitudes and occasionally deposited ash on the island. Periods where ash was visible in the emissions did not correspond to explosive seismic or acoustic signals, suggesting that the ash was produced by weak wall fragments falling into the gas stream through the active vents and not from eruptive activity. Seismicity was characterized by low levels of volcanic tremor and occasional volcanic earthquakes.