I am quite new and as I understand there is a tag natural=crevasse for glaciers.
Since crevasses move over time, I have a dataset containing the crevasse danger area, which could contain multiple crevasses, but it indicates the area where crevasses have to be expected and how dangerous, big, many they are.
How would you add this to osm? It is polygons with a classification from 1 (least dangerous) to 3 (most dangerous).
Is there a symbology for more or less crevassy terrain on glaciers?
Thank you 
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This is an interesting question. Many glaciers move at rates of more than several meters per year. This would imply that individual natural=crevasse elements in OSM are likely to become stale fairly quickly – if they’re not already out of place because of the age of the data used to map them.
However, crevasses do form in predictable locations on glaciers and many of these locations are determined by aspects of the terrain that do not change so quickly. E.g., along the margins of a glacier or where the glacial valley widens, bends, or changes slope. This would imply that an area where crevasses are likely may be more permanent than the individual crevasses themselves.
I’m not sure this is something that has been mapped so far, but perhaps it may be possible to use Key:hazard - OpenStreetMap Wiki for this situation.
Where did you get this data set? Is there some specific guidance on the use of the data?
As you say, they form in the same area, so a polygon is quite fitting to indicate the area, and some nice symbology could be used.
Like this example from swisstopo: what3words curdling.ally.geniuses
Here is the dataset published by LMÍ and has been fournished by the icelandic met office which monitors it. It is regularly updated.
Here an overview of the data and its attributes:
https://gis.lmi.is/geoserver/vedur/wms?service=WMS&version=1.1.0&request=GetMap&layers=vedur%3Asprungukort&bbox=271365.25%2C336027.90625%2C681066.375%2C641404.3125&width=768&height=572&srs=EPSG%3A3057&styles=&format=application/openlayers
Here the geojson file:
https://gis.lmi.is/geoserver/vedur/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=vedur%3Asprungukort&maxFeatures=100000&outputFormat=application%2Fjson
I am a bit new to add data so I have never imported polygons and would like to learn it and help the community with this data.
