Thursday, January 08, 2009 8:24 PM -
ArcGIS-Explorer-Team
Three ways to view a good shaker
Well, we were sitting around this evening wondering what our first post for 2009 would be, when the answer came in the form of a little roller coaster ride, thanks to an earthquake whose epicenter was just 6 miles from ESRI. We've covered earthquakes here on the blog plenty of times before, so we thought we'd do something a little different and take a look at the USGS earthquake data in 3 different ways as it's published at the USGS site.
First we viewed the GeoRSS feed. The connection was already stored in our list of connections since we've used that GeoRSS feed before. We just opened up the connection by choosing File > Open, and then choosing Servers in the Open Content dialog. Once we did, we could just scroll down the list of our remembered connections to find the quake feed to view it.

The feed displays all the quakes greater than magnitude 2.5 over the past day. We also used Find Address to locate ESRI, and used Measure to determine the distance from ESRI to the epicenter of the quake, which was just under 7 miles.

Next we opened the KML published on the USGS site showing all quakes greater than 1.0 in magnitude over the past 7 days. Note the display overlay in the upper left that came along with the KML, and the small aftershock (1.7 magnitude) located within a half mile of the initial temblor.

Finally we opened the USGS quake data delivered as a comma-delimited text file. We clicked on its link at the USGS site to view it in a browser, and this is what we saw:

We saved the file out as a text file, and took a look at it using Notepad. The first line in the file had field names, which was just perfect, but we had to do some minor edits to pull in the information the way we wanted. We removed quotation marks (using a global search and replace with a space) from around a combined day/date/time field, and added the extra field names to match the new formatting on the first line. We saved the file, then chose Tools > Import File to open the file import wizard.

In the first dialog we just accepted the defaults. Note the data preview panel at the bottom of this dialog which shows us how the text file is being parsed. This was especially useful since we could verify that we correctly made the edits to the file mentioned above.

After clicking Next, in the following dialog we again accepted all the defaults (the latitude and longitude fields were already found, since they had been named "lat" and "lon" in the text file) and chose "Magnitude" as the title field (so we could view it as we hovered over the location with our mouse) and "Region" as the description field.

Then we chose a symbol, and here's our map with the quake information imported from the text file.

This file contains all the magnitude 1.0 or greater quakes for the last day, and you can see there's been lots of activity in southern California during that time period.