INGV reported that a series of paroxysmal events separated by relative calm periods at Etna began on 16 February and continued at least through 23 February. The first episode began late on 16 February, characterized by gradually increasing Strombolian activity at the E vents of the Southeast Crater (SEC). Overflows of lava from the crater at 1805 caused a partial collapse of the cone and a pyroclastic flow that traveled 1.5 km along the W wall of the Valle de Bove. Lava fountains afterwards rose 500-600 m high. An eruptive plume rose several kilometers and drifted S, causing ashfall in areas as far as Syracuse, 60-80 km SSE. Lava flows advanced into the Valle de Bove and the Valle del Leone, and produced explosions in areas where they interacted with snow cover. Activity ended around 1900.

After a 30-hour pause the second paroxysmal episode began at 2330 on 17 February with overflows of lava from the eastern SEC vents. Lava fountaining began just after 0100 the next morning. Lava flows traveled towards the Valle de Bove, NE, SE, and SW. The eruption plume drifted SE, causing ashfall in Zafferana Etnea and Acireale. The lava fountains reached maximum heights of 600-700 m then ceased around 0140.

After another pause lasting about 32 hours, lava overflowed the SEC at around 0855 on 19 February. A rapid increase in explosive activity followed and lava fountaining began during 0945-0950. At 0953 lava fountains emerged from the S, or saddle, vent. At this time there were “fan-shaped” lava fountains rising from 4-5 vents orientated E-W. The eruption plume rose 10 km (32,800 ft) a.s.l. and drifted SE, again causing ashfall in downwind municipalities. Lava flowed S and towards the Valle de Bove causing explosions where they interacted with snow. Explosive activity ceased at 1110. Lab analysis of lava samples collected during 16-19 February eruptions showed that the magma was the most primitive over the past 20 years, meaning that the composition had changed little from its formation at depth and that it ascended quickly.

Weak Strombolian activity was visible in the late afternoon of 20 February. At 2230 a small lava flow descended a deep notch at the E end of the SEC and traveled towards the Valle de Bove. By 2300 the Strombolian activity had shifted to pulsating lava fountaining. Beginning at 0100 on 21 February more western vents became active and the E vents jetted lava 600-800 m high. Activity intensified at 0128 with jets of lava that rose more than 1 km high and were sustained for about 10 minutes. An eruption plume again rose to 10 km (32,800 ft) a.s.l. Beginning at 0200 the lava fountain became smaller, and at 0220 explosive activity ceased. Lava flowed SW and into the Valle de Bove.

Periodic ash emissions rose from both the S and E vents later than evening. Lava overflowed the SE crater just after 2230 and advanced 1 km towards the Valle de Bove. Lava fountains and Strombolian explosions occurred at multiple vents. Activity intensified at 0128 on 21 February and lava fountains rose 800-1,000 m above the SEC. Lava flowed from the S vent and an eruption plume rose several kilometers, but activity rapidly ceased at 0220. Lava flows continued to advance in the Valle de Bove; the longest flows were 3.5-4 km from the crater, between elevations of 1,700 and 1,800 m. During 0430-0515 very intense explosions from multiple SEC vents ejected incandescent bombs that fell as far as the base of the cone.

Weak Strombolian explosions at the SEC crater were visible late on 22 February. The frequency and intensity of the explosions increased and by 2210 material was ejected onto the flanks. By 2305 jets of lava were 300 m high, and by 2327 lava fountains rose from a second vent. Lava overflowed the crater at 2328 and headed towards the Valle de Bove. Within the first hour on 23 February lava fountains rose more than 1.5 km high and a sub-Plinian eruption plume had risen several kilometers above the summit, making this episode the most powerful and intense compared to the previous four. Lava overflowed the S vent and descended SW. Lava fountaining suddenly decreased at 0115 on 23 February, though lava flows continued to be fed. Strombolian activity again intensified at 0450, accompanied by ash emissions. Two lava flows formed and traveled SW and SE, the latter was longest and reached 1,700-1,800 m elevation. The activity ended at 1000.

Source: Sezione di Catania - Osservatorio Etneo (INGV)

IMO raised the Aviation Color Code for Krýsuvík to Yellow on 24 February based on recent increased seismicity. Intense seismic activity had been detected for the previous few days and since midnight through the generation of the report at 1107 more than 500 earthquakes had been recorded. At 1005 a M 5.7 earthquake occurred 5 km W of Krýsuvík and at 1027 a M 4.2 was located in Nupshlidarhals, less than 1 km NW of Krýsuvík. The seismic unrest was unusual for the area in the context of the unrest in the Reykjanes peninsula that began in January 2020.

Source: Icelandic Meteorological Office (IMO)

KVERT reported that during 1100-1150 on 18 February a new vent opened on Klyuchevskoy’s lower NW flank, near Erman glacier at elevations of 2,500-2,700 m, based on satellite images. Snowfall in the area of Klyuchi during 18-19 February inhibited webcam views. Bright incandescence was visible in webcam images beginning at 0323 on 21 February, likely indicating an advancing lava flow. On 23 February the Kamchatka Volcanological Station team reported that lava was flowing from two vents and bombs were being ejected 50 m high. A lahar along the Krutenkaya River was visible in an area 7 km E of Klyuchi Village (30 km NNE). Bright incandescence over the two flank vents was identified in satellite and video images on 24 February. KVERT raised the Aviation Color Code to Orange (the second highest level on a four-color scale).

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Kamchatka Volcanological Station

SERNAGEOMIN reported that during 1-16 February the seismic network at Laguna del Maule recorded a total of 533 volcano-tectonic earthquakes. Two earthquake swarms were recorded during 15-16 February; the largest events were local magnitude 3.1, and were located 9.1 and 8.8 km SW of the lake at a depth of 1.9 km. The epicenters were near the area producing anomalous carbon dioxide emissions. Swarms were recorded in June and December 2020, and January and February 2021, with the largest events occurring during the most recent swarm.

The highest rate of inflation during the previous 30 days was 2.3 cm/month, recorded at a station closest to the center of deformation. The highest horizontal displacement was an estimated 1.4 cm/month from a station just SW of the center. InSAR data mostly showed agreement in the magnitude and distribution of the ground-based deformation data. Overall, the deformation rates were higher than maximum averages. On 22 February the Alert Level was raised to Yellow, the second lowest level on a four-color scale. ONEMI declared a Yellow Alert for San Clemente and recommended restricted access within a radius of 2 km from the center of elevated carbon dioxide emissions.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)

INSIVUMEH reported that seismicity at Pacaya increased around 0900 on 18 February. Incandescent material was ejected 200 m above Mackenney Crater and explosions produced gas-and-ash plumes that rose 450 m and drifted mostly NE and S. An active lava flow on the SSW flank was 1.1 km long and generated hot block avalanches from the flow front. A lava flow emerged on the SW flank on 19 February. During 19-20 February periods of increased activity lasted 3-5 hours; moderate-to-loud explosions were accompanied by rumbling and sounds resembling trains. Ballistics were ejected 300- 500 m from the crater and ash plumes rose as high as 450 m and drifted SW. Ashfall was reported in areas downwind including El Rodeo and El Patrocinio. A lava flow on the S flank was 800 m long and produced incandescent blocks from the flow front that descended 500 m.

Strombolian activity increased on the morning of 20 February but fluctuated throughout the day. Ash plumes, that were dense during periods of heightened activity, rose 450 m and drifted 10-25 km S, SW, and W. As it grew darker lava fountains were visible rising 300-400 m and ballistics were ejected as far as 500 m from the crater. The lava flow on the S flank had lengthened to 1.1 km. Strombolian explosions continued during 21-22 February, ejecting incandescent material 100-175 m high. Ash plumes rose 450-800 m above the summit and drifted possibly as far as 15 km NW, W, and SW, causing ashfall in areas downwind including San Francisco de Sales, El Cedro, El Rodeo, and El Patrocinio. Ballistics were ejected as far as 500 m from the crater. Blocks from the front of the lava flow descended 300 m. Weak explosions during 22-23 February ejected incandescent material as high as 100 m above the summit. A 900-m-long lava flow was active on the SSW flank. Ash plumes drifted 5 km S.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)

PVMBG reported that daily gray and sometimes black ash plumes rose 200-1,200 m above Raung’s summit during 17-23 February. Ash plumes were sometimes dense and drifted mainly N, NE, E, and S. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)

SVERT noted that thermal anomalies over Sarychev Peak were identified in satellite images during 9-10 and 12-14 February. KVERT reported on 19 February that the effusive eruption was over, though lava continued to advance in the summit crater and a thermal anomaly remained visible. KVERT lowered the Aviation Color Code to Green (the lowest level on a four-color scale).

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Sakhalin Volcanic Eruption Response Team (SVERT)