Scariest map out yet. From 12:45 today

[ericlp]

and hope for the best


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[bluesboy]

Yep, nothing's changed in that area since 1983.

[Midnight Rambler]

dakine: the "datum" of a map refers to its coordinate projection system, i.e. how you transfer coordinates from a more-or-less sphere to a flat piece of paper. North American Datum 1983 (and World Geodetic System 1984, or WGS84, which is NAD83 extended to the rest of the world) is now pretty much standard. If you look at older topo maps, you'll see that they are in NAD 1927 or Old Hawaiian datum, and the same coordinate point will be about 120 apart in the different systems. Some of the intermediate maps even have marks in the corners to show where the map boundaries would be in NAD27.

The actual topographic data was mostly compiled in the 1950's (I think? someone correct me if I'm wrong), and has been updated since then mostly for things like changing development and lava flows.