Hello Rolf - This is a pretty good question. Shishaldin currently has ongoing seismic tremor, and elevated surface temperatures with ash and ballistics ejected as recently as late October. Cleveland is seismically quiet (it's webicorder is showing a lot of wind noise), and we haven't seen eruptive evidence there in a few weeks. However, because of Cleveland's recent history of intermittent explosions and lava domes, renewed unrest/eruption is very likely. Hope this was helpful, Cheryl -------- Rolf Tandberg wrote: I have been looking at the webicorders of the 2 active volcanos for some time now. To my untrained eye, both seem to have similar episodes of unrest. What is the difference between the 2 that causes one to be at the yellow alert and the other at an orange level? Thanks. -- Cheryl Cameron Geologist, Alaska Volcano Observatory Alaska Division of Geological & Geophysical Surveys voice: 907-451-5012 fax: 907-451-5050