GVP Weekly Volcanic Activity Report for August 31-September 6, 2011: Cleveland’s dome, Lewotobi in Indonesia and a glowing Poás

Quick update to catch us up a little on the week – and what better way to do that than to use the Smithsonian Institute/USGS Global Volcanism Program Weekly Volcanic Activity Report. Lots of good tidbits that we haven’t discussed and a lot that we have …

Highlights include:

Alaska: The dome on Cleveland in the Aleutians continues to grow – and with it, the chances of an explosive eruption at the volcano if the vent is plugged by the new dome. AVO will be keeping close tabs on the volcano for the sake of the many aircraft that fly over the the Aleutians to/from Asia.

Indonesia: We have talked a bit about Tambora*, but the alert status at another Indonesian volcano has been raised from 1-2 as well. Lewotobi on the island of Flores has been rumbling so a 1-km exclusion zone has been defined around the volcano. Lewotobi last erupted in 2003 and has a history of small VEI 1-2 eruptions over the last century (the image to the top left is Lewotobi erupting in 1915, taken by A.I. van Aernsbergen).

*UPDATE 12:30 PM EDT: Eruptions reader Mr. Moho brings us news that the alert status at Tambora has been raised from 2 to 3. The update from the PVMBG says that increased seismicity and tremor at Tambora prompted this elevation of the alert status. An exclusion zone has been set up around the volcano. I’ll post more details as I find them.

Costa Rica: Poás in saw the first observation of daytime incandescence since 1981. However, the reason for this change has not been determined as of yet – it could be magma extrusion or potentially changes in the hydrothermal plumbing system.