BUFFERING USING QGIS
The Volcano and the Buffer Mon, 04/27/2009 - 20:19 — Gary Sherman Here in Alaska we have over 130 volcanoes with more than 50 being active in about the last 250 years. Presently Mt. Redoubt is in an eruptive phase and has been since March 22. Ash from the volcano has fallen in a number of communities and areas throughout the state. A couple of weeks or so ago the reports from the Alaska Volcano Observatory indicated the ash was falling within 30 miles of the volcano. I decided to do a quick analysis to see what areas might be affected. This is an example of simple analysis with GIS. We just get the location of the volcano and create a 30 mile buffer and then visually determine the affected areas. To do this we need data for towns and the location of the volcano. We could use a volcano layer if we had one, but in this case I'm going to use a simple method to create a point shapefile from text data. The AVO website indicates that Mt. Redoubt is located at Latitude...