A "lahar" is a volcanic mud and debris flow- volcanic in the sense that the dominant clast type is volcanic in origin. They may or may not be associated with on-going volcanic eruptions. As we'll see in coming days, there are at least two lahars in this panorama, possibly three or even more. Their compositions overall are similar enough that, with the exception of the finer-grained channel fill to the upper left, it's not easy to make distinctions. On the right edge, we can barely make out some finer-grained, yellow-to-orange ash tuff beds, which are gently dipping to the left (NNW, if I have the location right.) between the channel on the right and the beds on the right, is what I'm for the time being presuming is a single larger lahar deposit. I say "for the time being" because I may notice something that indicates otherwise as I scan over these photos from 2 1/2 years ago.
Speaking of "2 1/2 years," that's plenty of time to forget details, like the location, for example. The closer I look at the indicated FlashEarth location, the more confident I feel I've got it right, but I'd be remiss in not admitting I'm still a little uncertain. For one thing, it's farther east and closer to Adel than I recalled.
Photo stitched in HugIn. August 19, 2011.
FlashEarth Location.
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