The NASA Earth Observatory has posted some excellent images of Matua Island in the Kurils that show the before and after of the Sarychev Peak eruption of June 2009. There are some impressive changes ... so lets see if you can spot them! Post your comments on whats changed and why and I'll chime in periodically with what I've noticed.
AFTER: Matua Island and Sarychev Peak in late June 2009 (big version)
Assuming these pictres are North at the top, it appears there is new land mass north east of the volcano, and south west of it so far as I can make out. Shape of the Island has changed, or appears to have slightly.
No more snow!
And there appears to be a whole section blown away on the north of the summit
Yes, your two appreciations are right: no snow and new land masses. And I say one more, that is the anhililation of part of the vegetation of the island (except of the snow covered places) that are marked in red.
The rivers seem to have been filled with Lahars and left deposits in various harbors, delta's, (correct word?) around the Northern (grayed out) side of the Island. Since red is supposed to represent vegetation in these pictures maybe all vegetation on the Northern side was covered with ash or burned by pyroclastic flows - or destroyed in the blast of an eruption. I'll just assume though it was covered by ash.
Foliage in general I suppose is much more robust in June than in May. That is why the red is so much stronger in the June 2009 picture than in the May picture.
I am uncertain as to whether the summit moved or not. The dark area in the June 2009 picture - it could be a shadow from the cloud almost directly at the summit? Plus the May 2007 picture had a snowcapped peak. It is hard for me to see detail through the snow glare.
I look forward to reading other thoughts on these pictures. I put the photos above each other in Photoshop layers to flick one picture on and off and can see a noteable increase in the landmass on the Northern side in the June 2009 picture compared to the May 2007 picture.
I don't know enough about the normal state of the volcano in June to definitely attribute the missing snow line to the volcanic eruption rather than normal June melting. However, again the deltas in the North seem to have filled with material, the harbors in the South don't seem to have changed much - so I can't attribute the greater land mass in the North to just a low tide (since the land in the south hasn't expanded into the ocean) - the Northern growth of the Island has to be the remnants of a lahar.
Simon: Yes, there is an emblem in the bottom right hand corner of the picture an N ^ that points to the top of the photo as North.
I appreciate these brain exercises! Any other knowledge that you will like to impart such as why one picture is so much darker than other - I'd like to learn that too. Can you tell when each of these pictures were taken (meaning daytime or nighttime)?
I can't see any new land really even when I blow the image up but that does look like a shadow over the summit to me,wish there were not clouds over the summit in the before picture so we can see how the summit has changed,hard to tell becuase of that issue.
On secnond thought the island is bigger is that is what you meant by new land. soory that I somehow meesed that part up.
The big splotches of ice are gone.
There seems to be a plume in the bottom image with a few 'puffs' (unless those happen to be small clouds which just happen to sit above the plume).
Top = cloudless, bottom = fluffy clouds everywhere
Old (possibly magma flow - I'd guess magma because there wasn't much vegetation in it before) now seems covered in a new coating of sand.
The lee side of the island is nicely grassed over ('before' image may have little apparent vegetation due to cold temperatures). It's a bit early for vegetative regrowth in the sterile sand so the settling sand appears to have predominantly covered the top 3/5 in the image.
Many mud flows evident through the vegetated area (well, also evident in the newly buried unvegetated area).
And that's it for me - I can't find Wally anywhere.
Ok, my 2c.:
I wouldn't call them harbors (that's a sailor's term applying safe anchorage) , let's just go for bays. There are noticeable deposits on the northern coast, filling a couple of bays (will be interesting to see how these stand up to wave erosion in the coming months) and one on the southwestern coast. At first I thought there may have been a landslide here because you can see a noticeable scarp in the June photo but, if you look closely, it is also there in the before photo.
There are also smooth deposits to the NNW of the volcano although they don't look like they extend (much) beyond the coast. My bet is that all of these thick deposits were caused by pyroclastic flows not lahars. There is one lahar, however, and that is to the SE of the peak closely following a river bed. This ties in nicely with the shots taken by the astronaut from the ISS where you can see the lahar occurring (nice fluffy white clouds suggesting high H20). Amazingly, for such a big eruption, there doesn't seem to be much ash at all to the lee side of the vent...
ok. how did I do? :lol:
Nice job, everyone! You got most of what I've noticed and then some.
There is definitely a lot of ash fall/pyroclastic material on the north end of the island. It does a nice job of showing the direction of the prevailing winds on the island - and the direction that the pyroclastic flows moved. There are a couple of aprons of pyroclastic flow material that have added (albeit likely very temporarily) to the island on east and west sides. This material is likely unconsolidated so the wave action will make quick work of it.
Good job spotting the small lahar on the southeast side of the volcano - I missed that one. It seems to be the only major volcanic feature on that side of the island. There are also likely lahars overlying the ash/pyroclastic material on the north part of the island (as Bruce suggested) - definitely hard to tell from these images. However, I did want to point out that a lahar shouldn't have any co-genetic cloud above it when it is produced, like a pyroclastic flow has. The whiteness of the ISS image just might reflect higher water content in the ash of a column collapse pyroclastic flow or maybe even a trick of the light.
I stared at the crater trying to decide if it looked different as the roachman suggests. It could be a larger crater area, it could be the crater minus any snow, it could be a trick of shadows. Likely there was some change in the shape of the crater due to the size of the eruption.
Thomas - I would guess the changes in brightness in the images are likely related to the image processing. Any satellite folks want to chime in?
Good job, all!
Love it that I always keep learning something new about stuff I thought I knew something about! This feature on the SE intrigues me more and more.. I guess what you mean about "cogenetic cloud" (even if I don't know the word!!) .. is that the cloud in the ISS photo looks to be ash (and steam) laden.. which would rule out a lahar, because lahars are not usually accompanied by billowing clouds of ash.. (thinking back.. there are some great pictures of lahars coming down the ski slopes at Mt. Ruapheu like black snakes.. and it is obviously not one of those). So obviously it must be a small PF. What's amazing about it though (conjecturing wildly here) is that it seems to hold enough heat to turn the river into steam as it descends down the valley. Interesting too how far down the valley it descends, as though the steam "lubricated" its passage... (or possibly the deposits we see in the photo are from later rain and normal erosion, but I'll go for my first interpretation, as this is what you see in the ISS photo).
I love this kind of exercise Erik, makes me want to be a student!
Erik, in case you have not seen this yet.
This is an animation of the Saraychev eruption taken from the ISS.
A couple of people have mentioned summit shifts. I would suggest a little caution in interpretation here, as ASTER (the instrument used to make these images) can be steered off nadir (i.e. it is not necessarily looking straight down) which causes a parallax effect, making the summit seem to jump slightly to the west in the recent image which was taken with more of an off-nadir viewing angle.
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What a great post!
Seriously? Is article bull crap? I have to be missing something here...