This page tells how to find and disply data for earthquake locations, depths, and magnitudes.
The GEON IDV can also display with
focal mechanisms.
The GEON IDV
displays earthquake locations in map views and in 3D displays with depth,
anywhere in the world, in any scale and map
projection. You can
show epicenter locations, locations colored by magnitude or depth, and locations sized and colored by
magnitude. You can choose sizes and colors for earthquake symbols.
You can overlay earthquake symbols with other geophysical, GIS, and map data.
Display symbols include a 3D cross for location, circles colored by
magnitude or depth, and circles sized by magnitude.
Other displays are available to
show earthquake focal mechanisms.
Displays types include map views, vertical cross sections, and a rotatable 3D globe, and may include time animation.
The IDV has full interactive controls in 3D including zoom, pan, and rotation, and
tools to change map projections and background maps.
Where to get Data for Earthquake Locations, Depths, and Magnitudes
Plot This Week's Earthquakes from the USGS
You can plot this week's earthquakes, without loading any data file, using the IDV's main menu command
"Displays -> Locations -> Earth -> Earthquakes"
The IDV display controls let you change point symbols, colors,
and plot density (cluttering) as usual.
The earthquake data is from the USGS, supplied by an RSS feed.
The IDV label lists magnitude;
in the IDV display control's "Locations" tab you can see depths listed,
and in the "Selected" tab panel you can see more data about an earthquake including a web link
to the USGS Earthquake Center data page for that event.
With the next sources you can use earthquake catalogs of locations and
magnitudes for any place in the world, ready to use in the
IDV. You can load these data sources as URLs directly
into the IDV (Dashboard window -> Data Choosers panel -> URLs entry box):
The IRIS Earthquake Browser
Engdahl and Villaseñor, Global Seismicity 1900 - 1999 "Centennial Catalog"
A data file of the catalog for the IDV: http://geon.unavco.org/unavco/earthquakes/CentMagCatalog.nc (time in years only)
(Data publication: Engdahl, E.R., and A. Villaseñor,"Global Seismicity 1900 - 1999," in W.H.K. Lee, H. Kanamori, P.C.Jennings, and C.
Kisslinger (editors), International Handbook of Earthquake and Engineering Seismology, vol. 81 A, Chapter 41, pp. 665 - 690, Academic Press, 2002.)
See also
Centennial Earthquake Catalog.
Sample IDV display - 'Ring of Fire' Earthquakes
The USGS NEIC Worldwide
Earthquake search
(from the National Earthquake Information Center, PDE data):
You can find other earthquake catalogs online, such as the
The Pacific Northwest Seismic Network catalog,
and the
Advanced National Seismic System's
Catalog,
and easily convert their data into csv files.
See also the USGS list of other catalogs
and other earthqauke data.
How to run the IDV and connect to data
To install and start the GEON IDV, see
Download & Run the GEON IDV.
To load data in the GEON IDV, see
Choosing Data Sources and Connecting to Data Sources.
There is information below about putting
seismicity
data in formats for the IDV.
Seismicity Displays
Click on an image to see full size. All displays in the IDV are in full 3D and
can be rotated in any direction and rescaled in the vertical.
The second, third, and fourth pictures below were made from one IDV display, with
differing points of view and map settings. How to make the displays is after the pictures.
Seismicity of Mt. St. Helens (side view).
(data courtesy of Greg Waite)
Map view, earthquake locations under Japan, colored and sized by magnitude,
(data courtesy of Francis Wu)
Vertical plot of earthquake locations under Japan, from south,
colored and sized by magnitude
(data courtesy of Francis Wu)
Oblique view of earthquake locations under Japan, colored by depth,
plotted as "Locations 3D cross" symbol (data courtesy of Francis Wu)
Map view of earthquake locations under Japan, colored by magnitude,
showing Transect View control (data courtesy of Francis Wu).
A Transect View is a vertical cross section (of any azimuth) with
preset end locations, depth and thickness.
Transect View of earthquake locations under Japan, colored by magnitude:
events that fall inside a box 40 km wide (data courtesy of Francis Wu)
IDV data readout when you click on an earthquake symbol in the seismicity displays:
Making Displays
First set the display to a
map projection (map area)
and a
vertical scale
suitable for your data.
Connect to a data source
with the "GEON IDV Dashboard" window, "Data Chooser" tab.
For local files choose the "Files" section, navigate to the file on your local disk,
choose the Data Type from the pull down menu, and click
"Add source." For data sources with an HTTP server, use section "URLs."
If your data is in a .csv file, use Data Type "I'm feeling lucky" which means the IDV recognizes the
data type from the file name extension. If your seismicity data is in a NetCDF (.nc) file, choose
Data Type "NetCDF point data."
After you
connect to a data source,
the Dashboard window shows the "Field Selector" for that data.
To make a display,
in general you choose (click on) a Field name in the "Field Selector," then click on a display type
in the Displays panel of the same window, and then click on the "Create Display" button.
All seismicity data is Field type "Point Data," and the Displays panel shows the
choices "Point Data Plot" and "Point data list." Just click "Point Data Plot" and click on
the "Create Display" button.
The first display will use plot symbols called "Locations 3D Cross" (or whatever
happens to be first in the Layout Model list).
When a display is made the Dashboard window
shows the "display control" panel for that display. To use another plot symbol,
choose one from the pull-down menu called "Layout model" or "Station model," such as Earthquakes colored by magnitude.
Read more about
Point data plots
and
Working with the Point data Plot Symbols using "Layouts Models"
and
Color a Point Data plot symbol using Layout Models
To zoom, pan, and rotate see
Zoom, pan and rotate.
To make a transect display, see
Transect View.
A Transect View is a vertical cross section (of any azimuth) with
preset end locations, depth and thickness.
Seismicity Data Formats used by the GEON IDV
For seismicity data, the IDV can use two data formats, csv files and NetCDF files.
For complete details see
Point data in CSV files
and
NetCDF for the GEON IDV.
CSV files have the advantage of simplicity; and the disadvantage that the files contain almost no
description about the data. NetCDF files are a little harder to make but have many advantages. They contain
metadata which may be very detailed, including details such as
full credits about data creators, processing, and origins. They are smaller than ascii files for large data sets. The internal metadata can be used for
automated searches for data in time or spatial ranges. NetCDF files work on any platform that has software to read them.
They are very suitable for sharing data, online archives, and so on.
CSV files are simple ascii files with one earthquake per line, with comma separated values.
Here is a
sample csv seismicity file.
Use it as a template for your data. Note that the
first two lines must be exactly the same in all cases. Note that depths ("Altitude")
are negative downwards below the surface,
and note the time format. The IDV can plot all times at once, each time in one display, and do time animation.
unavco.org).
