USGS Recorded Magnitude 6+ Earthquakes, 1900 - Present
This Earthquake History web page is a chronological map-oriented display of earthquakes of magnitude 6 or greater that have occurred and been recorded worldwide between January 1, 1900, and the present. This page uses data collected by the United States Geological Survey (USGS), which makes it available on line for access or download. There are approximately 8,400 earthquakes in the local database. You enter search criteria, optionally including a designated geographic area, and the results are presented in both a list format and on a map display. The display is built using GoogleMaps, so you can zoom, pan, and switch views as in a standard map-based application. Here are a few examples.
Static Display example - results displayed immediately
Animated Display example - results displayed in a time simulation
The 'Ring of Fire': 6,110 quakes in 44 Years
Specify a date range, magnitude range, depth range, display type, and optionally, isolate a geographical area of interest. The application retrieves events that match ALL criteria:
Sample Search Parameters Form
- Enter a Start Date and optional End Date for the range of interest. If no End Date is entered, the default is the Start Date, and a single day's events will be displayed.
- Select a Magnitude range (lower magnitude bound to upper magnitude bound). Possible choices range from 6.0 through 9.9. The first number specifies the lower magnitude limit, the second number specifies the upper magnitude limit. All earthquakes between the lower limit and the upper limit are displayed. For example, selecting 6.0 and 7.9 retrieves only quakes between magnitude 6.0 and 7.9.
- Select an Epicenter Depth range from 0 to 1000 kilometers from the earth's surface (lower depth bound to higher depth bound). Possible choices range from 0 through 1000. The first number specifies the nearer distance to the earth's surface, the second number specifies the further distance from the earth's surface. All earthquakes between the nearer distance and the further distance are displayed. For example, selecting 0 and 50 retrieves all quakes between a depth of 0 kilometers through 50 kilometers inclusive. (Note: a depth of 0 typically implies an unknown or unrecorded depth, not that the epicenter occurred at the earth's surface).
- Choose Static, Animate Fast, or Animate Slow display. The Static display shows all earthquakes within the specified range of dates, magnitudes and depths. The Animate display runs a time-based simulation of the events. The Animate Fast simulation rate is approximately 10 days per second; the Animate Slow simulation rate is approximately 1 day per second.
- Choose a geographical area of interest by clicking the Earthquake symbol to the right of the Results button. The Geoloc Selector is displayed. It is a small blue rectangle that can be positioned by dragging and resizing to cover a specific geographic region. Note that the Geoloc selector is a toggle; clicking a second time turns off the selector.
Geoloc Selector (blue rectangle)
All Events matching the selected criteria are returned in a scrollable Event List in the left pane and are displayed on a map (note - latitudes above 80oN and below 80oS are not covered). This map implements Google-Map features including the ability to pan the map, zoom in and out, and switch between Terrain view (showing geophysical features) and Satellite view (showing a satellite photo montage).
All earthquake events that satisfy the search parameters are listed in a scrollable window in the left panel of the display. Event details include the earthquake date-time of occurrence, location, earthquake magnitude on the Richter scale, and epicenter depth. The location column is made up of clickable cells. Clicking a location cell identifies that particular earthquake on the map.
Sample Scroll List Result
STATIC DISPLAY: The earthquake events that match the search criteria are positioned on the map using colored icons to indicate depth. Magnitude is indicated by the size of the icon.
|M=6.0 - 6.9|
|M=7.0 - 7.9|
|M=8.0 - 8.9|
|M=9.0 - 9.9|
Click on an icon, and the following actions occur: the associated event in the Event List is highlighted. An information window opens at the icon location with a summary of the event. Click the X on the small window to close it.
Sample Information Window Pop-up
ANIMATE DISPLAYS: The earthquake events that match the search criteria are displayed on the map in chronological order, based on a clock rate of 1 day per second (Slow) or 10 days per second (Fast). An animation date clock is displayed at the lower left corner of the map.
Animation Date Display
A transient circle is displayed at the epicenter Geo-location, sized according to earthquake magnitude and color-coded according to earthquake depth.
Transient animation circles (satellite view)
In the above figure, the largest (yellow) circle represents the great 9.1M earthquake (with tsunami that followed) off the coast of northern Sumatra on December 26, 2004. Many of the embedded circles represent aftershocks that followed the quake (the scrollable list reveals no fewer than eleven of magnitude 6 or greater that followed within 24 hours). The large blue circle is an 8.1M temblor off Macquarie Island, New Zealand, that occurred three days earlier.
Tom Wible pointed me (indirectly) to the USGS site where the data is available for download (see http://flowingdata.com/2014/04/15/mapping-a-century-of-earthquakes/)
The basic idea for the transient display circles came from the Google Maps tutorials at https://developers.google.com/maps/tutorials/visualizing/earthquakes#circle_size
Sortable table columns: thanks to http://www.kryogenix.org/code/browser/sorttable/sorttable.js for providing the source code!