[HOT] landslides and imagery

john o'l ol.john.el at gmail.com
Mon May 11 15:59:06 UTC 2015

Also linking a website with links to a report on the Oso landslide as it is
somewhat familiar to me
For our purposes, some of the key points made are:  the initial phase of
the slide (most destructive/fastest and most distant runout) -- was an old
slide that had remobilized. 200 vertical meters of material which covered a
horizontal distance of 1000 meters.  So existing landslides can remain very
dangerous for a considerable period of time.  The 1 km runout, (or
"deposit" keeping with the tagging scheme I proposed  "area = deposit") was
not extraordinary based on volume of material, however it was extraordinary
relative to most peoples' perceptions -- I doubt anyone seriously
considered that a hillside that low and distant could be an active risk to
an area as far away as the main highway corridor.

After mapping some more landslides to my local machine but yet to upload
any to OSM, I'd like to update my proposed OSM tagging scheme:

hazard_type = landslide
hazard_prone = yes
area = scarp OR deposit
damage:event = nepal_earthquake_2015 OR pre_nepal_earthquake_2015
barrier = scarp OR deposit
source = DigitalGlobe, 2015-05 OR other as appropriate
landuse = brownfield



On Mon, May 11, 2015 at 8:00 AM, john o'l <ol.john.el at gmail.com> wrote:

> 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
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>> --
>> Prabhas Pokharel
>> http://prabhasp.com
>> twitter/skype/facebook/whatever: prabhasp
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