[HOT] landslides and imagery

john o'l ol.john.el at gmail.com
Mon May 11 15:00:06 UTC 2015


Thanks Prabhas,

Very interesting! Yesterday I was directed to the Earthquakes Without
Frontiers blog http://ewf.nerc.ac.uk/blog/ and a map linked from their May
8 post
http://ewf.nerc.ac.uk/wp-content/uploads/2015/05/Landslide_Update_2_08052015_SMALL.jpg,
apparently higher resolution is also available..

Cheers,
John

On Mon, May 11, 2015 at 7:10 AM, Prabhas Pokharel <
prabhas.pokharel at gmail.com> wrote:

> Another email to add to the list for those interested in doing landslide
> mapping:
> We at KLL were forwarded this landslide risk assessment layer:
> https://www.google.com/maps/d/u/0/viewer?mid=z6HUO2aILzmQ.kGtOdlu45GXY&usp=sharing
> which comes from here:
> https://sites.google.com/a/umich.edu/nepalearthquake/landslide-maps
>
> It may help those of us interested in finding lanslides have some areas of
> high risk where they could start looking.
>
> cheers,
> Prabhas
>
> On Sun, May 10, 2015 at 11:50 AM, Springfield Harrison <
> stellargps at gmail.com> wrote:
>
>> Hello John,
>>
>> With reference to your moving boulder, just wondering if that could be in
>> fact moving, i.e., not an image based coordinate shift as such.  I'm just
>> thinking that with aftershocks and general instability, many of these new
>> features are still sorting themselves out and traveling downhill.
>>
>> Can DG or Bing make stereo pairs available?  Likely a long shot, but
>> thought I would ask.
>>
>>                 Cheers . . . . . . . . Spring Harrison
>>
>>
>> At 09-05-2015 17:49 Saturday, john o'l wrote:
>>
>>> I've been focusing on landslides and have located several score that
>>> appear recent. Of these, a few are pre-quake and appear relatively stable,
>>> some are pre-quake but appear reactivated and many appear to have been
>>> associated with the quake and/or aftershocks. I've mapped several dozen of
>>> these so far. In my next email, I'll cover why you won't find them in
>>> osm... yet. For this one, I'd like to stick to post quake imagery and some
>>> of its quirks.Â
>>>
>>> There is an inhabited hillside that had numerous landslides, some
>>> predate the quake, but most are presumably related. So far I've mapped
>>> about half of them, those that are largest or appear to threaten buildings
>>> and pathways. There is Digital Globe imagery available from May 3 and May
>>> 8. It looks like QGIS easily operates with more than one coordinate system
>>> at a time. The center of a large boulder in the May 3 imagery (Longitude,
>>> Latitude; WGS84 EPSG:3857 x,y) is at
>>> 85.85659,27.83609;9557511.789,3228324.329, in the May 8 imagery it is at
>>> 85.85669,27.83656;9557522.728,3228382.865. Mind you, this is not a
>>> complaint, rather it is a concrete example of the variability with this
>>> recent imagery. Â
>>>
>>> A more extreme example is a slide that appeared to be partially blocking
>>> a stream in the May 3 imagery 85.90258,27.87818;9562631.312,3233623.303;
>>> -- it was completely obscured by a hillside in the May 8 imagery (probably
>>> taken from a more northerly or northwesterly vantage point.)Â
>>>
>>> Downslope (westward) from a likely reactivated slide located at
>>> 85.81987,27.90810;9553423.739,3237391.771 Â is a remote area that
>>> appears very hard hit. The May 8th imagery is mostly clouds, but the May
>>> 3rd imagery shows a blue rooftop at
>>> 85.80644,27.90818;9551929.301,3237402.414, it looks like there are several
>>> large boulders in the immediate area and there is not much left to tell
>>> there were more than 20 buildings nearby. While the boulders may have
>>> contributed, at the moment I think it is probable that the shaking itself
>>> was mostly responsible for the extreme level of destruction.Â
>>>
>>> One advantage of different acquisition angles is that some features may
>>> be discernible on slopes that don't ordinarily show up very well.Â
>>> Â
>>> Question to the HOT folks -- is there a way to specify the date of DG
>>> imagery we access through the proxy server?, Some of the May 8 imagery is
>>> starting to come up over the May 3 imagery without me telling it to. Â
>>>
>>> Best regards,
>>>
>>> John
>>> _______________________________________________ HOT mailing list
>>> HOT at openstreetmap.org https://lists.openstreetmap.org/listinfo/hot
>>>
>>
>>
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>
>
> --
> Prabhas Pokharel
> http://prabhasp.com
> twitter/skype/facebook/whatever: prabhasp
>
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