Roundup of Global Volcanic Activity
Bardarbunga (Iceland): No significant changes have occurred at the ongoing eruption in Holuhraun and the seismic crisis. The eruption itself continues with steady, very large lava output and is on its way to become the largest event in the past 150 years on Iceland. So far, it has erupted approx. 0.5 cubic kilometres of lava, covered 40 square kilometres at an average depth of 12 meters.
Sinabung (Sumatra, Indonesia): The volcano continues to slowly extrude lava feeding the large lava lobe on the southeastern flank. Occasional rockfalls and small pyroclastic flows have been observed in the past weeks. PVMBG reported that RSAM values from Sinabung were low and stable during 12-20 September. Earthquake signals indicating lava-dome instability were recorded and had increased from 96 to 110 events/day since the 5-11 September period. Seismicity also continued to signify growth of the main lava flow on the flanks; incandescent lava was visible at the top, middle, and front of the lava flow.
Kilauea (Hawai’i): (25 Sep) In the past few days, the front of the lava flow heading towards Pahoa has stalled its forward progress. There is still lava activity at a decreased level, but this is only widening the lava field instead of advancing further.
There is an interesting, perhaps coincidental correlation between the drop in surface activity and a decrease in summit tilt (presumably tied to pressure). Unusually, there is no corresponding decrease on Pu’u ‘O’o’s tilt signal, and the public is not in a position to decipher whether this is due to an unusual eruption geometry, or whether there is no real correlation. If surface activity increases within a day or two of the next summit tilt increase, that would suggest some correlation, but for now certainly Pahoa and its infrastructure have been granted a little extra time.
Shishaldin (United States, Aleutian Islands): AVO reported that, although cloud cover sometimes obscured views of Shishaldin during 17-22 September, seismicity indicated that a low-level eruption was possibly continuing. Elevated surface temperatures at the summit were periodically detected in satellite images. Minor steam emissions were recorded by the web cam on 17 September. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
Tungurahua (Ecuador): Activity at the volcano remains at moderate to high levels, consisting of strombolian and small vulcanian explosions. During the past week, ash plumes have been rising 2-3 km above the volcano. On 18 September ash plumes rose 2 km and drifted mainly NW. Ashfall was reported in Cusúa (8 km NW), Mocha (25 km W), and Chacauco (NW), and windows vibrated at the Tungurahua Observatory (OVT) in Guadalupe (14 km N). An ash plume rose 2 km and drifted NW on 19 September.