[HOT] landslides and imagery

Nama Budhathoki namabudhathoki at gmail.com
Sun May 10 01:50:05 UTC 2015


Hi John,

Landslide is one of the major issues. We can try to use local knowledge for
groundtruthing.

Nama



On Sun, May 10, 2015 at 6:34 AM, john o'l <ol.john.el at gmail.com> 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.
>
> 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.
>
> 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.)
>
> Downslope (westward) from a likely reactivated slide located at
> 85.81987,27.90810;9553423.739,3237391.771  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.
>
> One advantage of different acquisition angles is that some features may be
> discernible on slopes that don't ordinarily show up very well.
>
> 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.
>
> Best regards,
>
> John
>
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-- 
________________________________________________________________________
Nama R. Budhathoki, Ph.D.
Executive Director, Kathmandu Living Labs *(www.kathmandulivinglabs.org
<http://www.kathmandulivinglabs.org>)*
Cell: 977-9803571739
Office: 977-6205000
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