Volcanos

Roundup of Global Volcanic Activity – New Activity for the Week 1 September – 7 September 2021

Askja – Iceland : On 3 September IMO reported that inflation at Askja had begun in early August based on ground deformation data derived from satellite images and continuous GPS data. The uplift was centered at the W edge of Oskjuvatn caldera and vertically deformed at a rate of about 5 cm per month. Data indicated that the source of the inflation was at a depth of about 3 km and caused a volume change of about 0.01 cubic kilometers per month; the source was unknown, though most likely was caused by an influx of magma.

Kilauea – Hawaiian Islands (USA) : HVO reported that ground deformation beneath the S part of Kilauea’s summit ceased on 30 August and the earthquake rate decreased during 30-31 August. The data suggested that a magma intrusion had slowed or stopped. Earthquake rates and ground deformation remained near pre-intrusion levels through 7 September.

Pagan – Mariana Islands (USA) : Continuous gas-and-ash plumes from Pagan were observed in satellite images for most of 1 September, prompting the USGS to raise the Aviation Color Code and the Volcano Alert Level remained at Orange/Watch, respectively. The plumes drifted 150 km NW and SW at an altitude of 3 km (10,000 ft) a.s.l. The emissions briefly paused at 2300 and then resumed; satellite images acquired the next morning, on 2 September, showed gas-and-ash plumes drifting 650 km. A plume of ash and sulfur dioxide was identified in satellite data, drifting 150 km W at an altitude of 1.2 km (4,000 ft) a.s.l. early on 3 September. Ash deposits in and around the crater and on downwind parts of the island were observed in 4 September images. During 4-6 September gas-and-ash plumes rose to 1.5 km (5,000 ft) a.s.l. and drifted at least 400 km W. Sulfur dioxide emissions were observed in satellite data on 6 September; ash emissions paused sometimes during 6-7 September as activity declined. A robust steam plume possibly containing a minor amount of ash was visible in satellite data on 7 September drifting 24 km W at an altitude of 1.5 km (5,000 ft) a.s.l.

Pavlof – United States : AVO reported that seismicity at Pavlof was low, though elevated above background levels during 31 August-7 September. Inclement weather sometime prevented satellite and webcam views of the volcano. A sulfur dioxide plume was visible in satellite images on 2 September.

Whakaari/White Island – North Island (New Zealand) : GeoNet reported that beginning at 0630 on 2 September minor ash emissions from the active vent at Whakaari/White Island were visible in webcam images. The emissions were observed in satellite images drifting SW and reaching the Bay of Plenty coastline. GeoNet noted that short episodes of minor ash emissions had been recorded during the previous few weeks, though none were as sustained as the 2 September episode. Minor ash emissions were also recorded on 3 September, but then ceased. The webcam continued to record nighttime incandescence from the vent, at least through 6 September, suggesting that temperatures were likely 500-600°C. Steam-and-gas plumes were voluminous, and coupled with weather conditions, were easily visible from the coast. Deformation measurement showed a broad area of subsidence around the vent area, possibly from the release of pressurized gas at depth and the more voluminous plumes. Additionally, the ash emissions may have possibly been caused by wall fragments falling into the vent.

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