Recently we had a bunch of small earthquakes in the Oakland, CA area. I thought it would be fun to use Common Lisp to retrieve and display information about recent earthquakes.
I found that the USGS website has hourly, daily and weekly quake data available here.
Possible formats of interest are XML (RSS) and CSV. I decided to use the CSV format, comma separated files, since XML seemed like overkill.
What I wanted to do was to find recent earthquakes near where I lived. However, the data from USGS is of the form:
Src,Eqid,Version,Datetime,Lat,Lon,Magnitude,Depth,NST
ak,00074326,5,"January 09, 2007 23:59:55 GMT",64.1478,-150.1976,1.8,1.00,07
Time, location (latitude and longitude in decimal degrees) and magnitude, among other bits of data. The data is nice, but I needed two things to make it useful:
- filter out the coordinates I didn't want, and
- convert latitude/longitude coordinates into city names.
I wrote cl-geocode to do the heavy lifting, which allows us to do something like this:
cl-user(3): (get-quake-info (place-to-location "Oakland, CA")
:period :week
:larger-than nil
:within 1.0)
;; Downloading quake data...done.
(("Friday, November 12, 2010 20:02:05 UTC" "Gilroy, California"
#<location 36.9678,-121.5598> 1.2)
("Friday, November 12, 2010 10:16:24 UTC" "Healdsburg, California"
#<location 38.6048,-122.9313> 1.3)
("Friday, November 12, 2010 09:40:48 UTC" "San Francisco, California"
#<location 37.7302,-122.566> 1.3)
("Friday, November 12, 2010 08:11:09 UTC" "Cobb, California"
#<location 38.7955,-122.7797> 1.1)
("Friday, November 12, 2010 04:02:18 UTC" "California"
#<location 37.4698,-121.8323> 1.9)
("Thursday, November 11, 2010 23:01:05 UTC" "Cobb, California"
#<location 38.7518,-122.7188> 1.0)
("Thursday, November 11, 2010 21:23:16 UTC" "Cobb, California"
#<location 38.802,-122.7972> 1.1)
("Thursday, November 11, 2010 20:52:56 UTC" "Spanish Flat, California"
#<location 38.3727,-122.1635> 1.9)
("Thursday, November 11, 2010 16:00:51 UTC" "Cobb, California"
#<location 38.788,-122.777> 1.6)
("Thursday, November 11, 2010 15:42:57 UTC" "Cobb, California"
#<location 38.8022,-122.8117> 2.0)
...)
cl-user(4):
The :within keyword value is in decimal degrees. A degree of latitude is approximately 69 miles. So 3.0 degrees is a little more than 200 miles in latitude. I use this for longitude, as well, but a degree of longitude changes with latitude, from 69 at the equator to 0 at the north and south poles.
The :period keyword value can be :hour, :day or :week.
The :larger-than keyword is a filter on magnitude. nil means all quakes. 2.0 means those larger than magnitude 2.0.
You need to download and install cl-geocode and cl-quakeinfo and to register, with ASDF, the .asd files. Then, you just need to:
cl-user(1): (asdf:load-system :usgs)
; loading system definition from /home/layer/src/usgs/usgs.asd into
; #<The asdf0 package>
; Loading /home/layer/src/usgs/usgs.asd
; registering #<system usgs> as usgs
; loading system definition from
; /home/layer/src/cl-geocode/cl-geocode.asd into #<The asdf0 package>
; Loading /home/layer/src/cl-geocode/cl-geocode.asd
; registering #<system cl-geocode> as cl-geocode
; Fast loading /home/layer/src/cl-geocode/package.fasl
; Fast loading /usr/local/acl82.64/code/aserve.004
;;; Installing aserve patch, version 3.
; Fast loading /usr/local/acl82.64/code/acldns.001
;;; Installing acldns patch, version 1.
; Autoloading for package "top-level.debug":
; Fast loading from bundle code/autozoom.fasl.
; Fast loading /home/layer/src/cl-geocode/zip-util.fasl
; Fast loading /home/layer/src/cl-geocode/geocode.fasl
; Fast loading /home/layer/src/usgs/usgs.fasl
;; Try this:
(get-quake-info (place-to-location "Oakland, CA")
:period :week
:larger-than nil
:within 1.0)
t
Don't forget to set your Google Maps API key:
cl-user(2): (setq cl-geocode:*default-key* "...")
where what is in the quotes is the API key you obtained from Google. See the instructions in cl-geocode for more information.