[HOT] landslides and imagery
heatherleson at gmail.com
Sun May 10 05:20:55 UTC 2015
HI Nama and John, while it is not satellite imagery, I've been following
the #nepalphotoproject. This collective seems to be documenting many
regions. With the quakemap and this photo stream could the landslide areas
be identified then verified with the imagery?
Thanks for all that you are doing
On May 10, 2015 4:52 AM, "Nama Budhathoki" <namabudhathoki at gmail.com> wrote:
> Hi John,
> Landslide is one of the major issues. We can try to use local knowledge
> for groundtruthing.
> 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,
>> HOT mailing list
>> HOT at openstreetmap.org
> Nama R. Budhathoki, Ph.D.
> Executive Director, Kathmandu Living Labs *(www.kathmandulivinglabs.org
> Cell: 977-9803571739
> Office: 977-6205000
> HOT mailing list
> HOT at openstreetmap.org
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