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2. SeisVolE basic navigation and dataÓ |
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File
Earthquakes
Eruptions
Map Options Help Exit |
Lawrence W. Braile, Professor
Department of Earth and Atmospheric Sciences Purdue University West Lafayette, Indiana Sheryl J. Braile, Teacher Happy Hollow School West Lafayette, Indiana January
14, 2002 |
Objective: Learn the basic operation of the computer program SeisVolE – an effective tool for exploring earthquake and volcano occurrences and plate tectonics. The SeisVolE computer program (written and distributed by Prof. Alan Jones, State University of New York, Binghamton) can be easily downloaded and installed (see teaching module 1) on your computer and then used to view “speeded-up-real-time” displays of earthquake and volcano activity on a variety of base maps. The program is powerful and easy to use and allows one to view many pre-assembled maps (views) or to select a new view and control the display.
Information: The SeisVolE
program contain extensive earthquake and volcanic eruption data files
(catalogs), and can be updated from the Internet to include the most recent
earthquake information. Additionally,
information on individual events can be obtained and statistical analyses can
be performed on the earthquake or eruption data by controlling the time, area
and magnitude ranges of the display.
The earthquake catalog (world.hy4) contains hypocenter (the hypocenter
is the epicenter location and the depth of focus) information (latitude, longitude,
depth, origin time, magnitude) for worldwide events of magnitude 5.0 and above
for 1960 to the present. The catalog
also includes earthquakes of magnitude 4.0 and above for the United States and
of magnitude 3.0 and above for California.
Hypocenter data can be updated to include current events through
connection to the Internet (see Teaching Module 13).
Additional catalogs can be created for specific areas and for additional
time or magnitude ranges using earthquake searches available on the Internet
and then plotted and analyzed using SeisVolE.
The volcanic eruption catalog contains eruption data for 1960 to early
2000. More information on the volcano
data, including a discussion of estimation of the magnitude (size) of volcanic
eruptions, is contained in the Help file of SeisVolE.
The program is very useful and produces
attractive maps. It is worthwhile to
have individual students use the program in a computer lab or with their own
computers. Alternatively, the program
can be used in demonstration mode in a classroom to illustrate interesting and
important earthquake and plate tectonic concepts. The seismicity
maps can be displayed for large and small areas (for example the world display
in Figure 2.1 or the view of California and Nevada in Figure 2.2).
Figure 2.1 Screen image of the SeisVolE display for
worldwide earthquakes and volcanic eruptions from 1960 to 2000. Dots are epicenters. Triangles are volcanoes. Heavy colored lines are inferred plate
boundaries. The Key provides
color-coded information on earthquake and volcanic eruption magnitude and
earthquake depth. Counters provide
information on numbers of events in the map area over the selected period of
time. This information can be used for
statistical analysis of earthquake and volcano activity. Buttons (near the bottom of the screen),
pull-down menus (not shown, at top of screen) and a slider provide display
control and information about the earthquakes and eruptions.
Figure 2.2 SeisVolE map (extracted from screen image)
of California and Nevada showing earthquakes from 1960 to 2000. Base map illustrates topography. Dots are earthquake epicenters. Dot size is proportional to magnitude of the
event. Blue lines are faults.
Basic Operation of SeisVolE: SeisVolE has many options that allow the
user to control the data that are displayed and the appearance of the maps that
are produced. A “help file” (from the
pull-down menus at the top of the screen) provides detailed information on the
program, data files and operation. An
auxiliary DOS program (EQSELECT, see Help, Contents) is available for searching the
earthquake data file. Some basic
operation options and information are:
Views – Use the buttons
on the screen to select pre-assembled maps.
The Back button will
return you to the menus of views. You
can create your own views with the “Make Your Own Map” option under the Map menu.
Key – The map key on
the right side of the screen (Figure 2.1) provides information on the
earthquakes and eruptions that are plotted, including a counter that can be
useful for analyzing the statistics of earthquake and eruption sequences. Symbol sizes, ranges and colors can be
changed from the Earthquakes and Eruptions pull-down menus.
Playback
Control
– Buttons and a slider bar for controlling the display of the earthquake and
eruption data through time are provided at the bottom of the screen. You can turn the display of earthquakes or
eruptions on or off, adjust the speed of the playback (speeded-up-real-time),
the magnitudes that are displayed, and control the playback with buttons (Pause, Repeat, Rewind, etc.) and a
slider control, similar to the operation of audio equipment. The Step buttons allow you to step through the data (forwards or
backwards) one event at a time and see the information on that event (location,
origin time, magnitude; earthquake or volcano) on the screen. This feature is very useful for identifying
a specific event in the earthquake catalog or finding the event that is closest
to a specific time or location.
Menus – The pull-down
menus at the top of the screen provide additional control of data that are
displayed and map appearance. Figure
2.3 shows the selection screen that is displayed at the beginning of the
SeisVolE program. Standard views are
opened using the buttons. Various
controls and options of standard views and views generated by the user are
selected using the pull-down menus (at the top of the screen, for example in
Figure 2.3).
Figure 2.3. Selection screen at the beginning of the
SeisVolE program. Pull-down menu items
are shown on the upper line (File, Control, etc.). Selection buttons (Asia
Group, Pacific Group, etc.) allow opening of standard views.
You can Set Dates (range of dates;
useful for analyzing statistics of sequences or finding an event of interest)
of the events to be displayed from the Control menu. The Earthquake menu allows one
to view the event catalog. The Map menu allows you to see the range
of latitude and longitude that is included in the view and to make your own
maps to “zoom in” on an area. The Options menu allows you to display the
coordinates (latitude and longitude) of the cursor so that individual locations
may be determined, to make a bitmap image of the screen that can be plotted or
exported to another file, and to update the hypocenters (earthquake data) from
the Internet (this capability is very useful as it allows you to display the
location of a very recent local earthquake or large earthquake or any event of
interest and to see its location in relation to the historic seismicity. Specific menu items (at the top of the screen) of most interest include:
File – The File menu allows one to select various
views although the views can also be accessed by the buttons on the screen and
the Back button. Additionally, if you generate a new view by
changing the control, earthquake or eruption information or by
the Make Your Own Map option (Map menu), you can save that view for
later access by using the Save
as
option.
Control – The Control menu allows you to set the dates (Set Dates) for the data to
be displayed and the and Speed of the playback
(speed can also be set using the button control at the bottom of the
screen). The Map View and Set Up Cross-Section View controls are
useful for viewing the earthquake data in a cross-section view. For details on using these controls, see Teaching Module 14.
Earthquakes – The audio
output associated with each earthquake can be turned on or off with the Audio control. The Earthquake menu allows one
to select the appropriate earthquake catalog using the Earthquake File control. Generally, the world.hy4 catalog is
already selected and is the appropriate catalog to use. However, if one creates a new catalog for a
specific region, one can select it for the current view using the Earthquake File control. Data in the earthquake catalog can be
displayed and read using the Edit
Earthquake File… menu item. The Magnitude/Depth Scale control is also
useful to set the color-coding of the earthquake depths and the size of the
dots for adjusting the appearance of the display.
Eruptions – The Eruptions control includes
an on/off control for the audio (Audio) associated with the eruptions and control of the Volcano Names display.
Map – The Map controls of most use are: Latitude/Longitude – to set
(or check) the latitude and longitude range of a view; Annotations – to add
geographic and text information (Title, Scale, City names, etc.) to a map display; Shaded Terrain – to select the
elevation file for a shaded terrain topographic map, particularly for the Make Your Own Map option; Make Your Own Map – to select an area
on the current view to make you own map – using this option, one can “zoom in”
on a specific area to view the earthquake and volcano activity – shaded terrain
can be added to the make your own map views using the elevation files; Plates – controls optional display of
plate boundaries; Redraw – to redraw the
map after a new elevation file has been selected.
Options – useful controls
include: Coordinates – to display the
latitude and longitude of the cursor location; Make Bitmap – to produce a bitmap image of the
current view that can be copied or inserted into another document such as a
Microsoft Word file (when you have a screen display that you’d like to save,
select Make Bitmap from the Options menu; you will be prompted to
provide a file name which will be given a file extension of .bmp, which stands for bitmap; the file
will be stored in your SEISVOLE folder; you can open the bitmap image with a
photo processing program such as Adobe Photo Deluxe, or import into an MS Word
document by selecting Insert, Picture, From File…; then “navigate” to the SEISVOLE folder
to select the .bmp file that you
saved); Update
Hypocenters via Internet – using this option, you can automatically update the
earthquake data file with recent hypocenters (your computer must be connected
to the Internet when you select this option).
Help – Access to the
SeisVolE help files for additional information on the earthquake and volcano
data, operating SeisVolE and the DOS programs for importing and exporting
earthquake data.
Exit – To exit
SeisVolE.
Summary: Working with SeisVolE is interesting and
educational. The program allows one to
make attractive maps of historic and very recent earthquake and volcanic
eruption data and to investigate the temporal and spatial distributions of
earthquakes and eruptions. For many
demonstrations, investigations and activities, the standard views and the
controls that are readily available on the screen are all that are necessary to
effectively use SeisVolE to explore earthquake and volcanic eruption activity
and related plate tectonics. However,
to investigate specific areas, events or phenomena, or to conduct independent
research projects, many of the controls and options that are described here
will be either useful or necessary.
Go to
List of SeisVole Teaching Modules (in Introduction to SeisVolE
Teaching…; Module 0)