Monday Musings: The end at Montserrat, more rock falls at Kilauea and a Shiveluch update

Monday is here again already …

A pyroclastic flow from Soufriere Hills heading towards the ocean. Note the large volcaniclastic debris fan being formed by repeated flows. Dated March 2006.

• The “Science Advisory Committee” at Montserrat in the West Indies suggests that the current eruption of Soufriere Hills on the small island could be drawing to a close. This is mostly based on the ever-decreasing seismicity under the volcano and that the volcano has not experienced any new dome growth or explosions over the last 6 months. Gas emissions have remained relatively constant over the last 18 months, so they warn that Soufriere Hills has not reached true “end-of-eruption” criteria (which vary from volcano to volcano – there not no universally-prescribed criteria to declare a volcanic eruption “over”).
• The crater area of Halema`uma`u at Kilaeua experienced another rock fall, this one caught on camera by the USGS HVO. The rockfall, which occurred on the morning of September 9th, did not produce as much ash as the fall from earlier this summer, but may have blocked some of the “glowing” from within the crater. Sulfur dioxide emissions from the Halema`uma`u vent still remain high – upwards of 900 tonnes/day.
• The alert status at Shiveluch was lowered from “red” to “orange” over the weekend. It appears that the ash plume since the explosions on Friday (9/11/09) may not have been as large, possibly reaching only ~6.5 km / 21,000 feet, but clouds obscured most of the eruption. The current status report:

Activity of the volcano continues: a new viscous lava flow effuses at the lava dome. Ash explosions > 10 km (> 32,800 ft) ASL could occur at any time. The activity of the volcano could affect international and low-flying aircraft. Seismic activity of the volcano decreased: only three explosive events occurred from 02:15 till 15:46 UTC on September 11

If you want to see images of the volcano before the eruption, including closeups of the dome, check out the KVERT page for Shiveluch.