Seismic-Eruption is a wonderful program conceived and written by Alan L. Jones at SUNY Binghamton. This program as well as his Seismic Waves program are part of the new Janet Annenberg Hooker Hall of Geology, Gems, and Minerals at the National Museum of Natural History of the Smithsonian Institution in Washington, DC which opened September 20, 1997.  We use Seismic-Eruption in Show-Me-Geology to demonstrate basic characteristics of earthquakes and volcanic eruptions and to engage kids in thought provoking questions. 

If you have a Windows machine you can download these programs from http://www.geol.binghamton.edu/faculty/jones/jones.html and use them in activities with your students.

Below is an example lesson using Seismic-Eruption that was developed for pre-service teachers at SDSU in the Natural Sciences 412D class.  There are all kinds of fun informative exercises you can have kids work on with this program. Have fun!

Go to the Start menu in Windows and select Programs, then Seismology and then "Seismic Eruption" which will launch the program. Press "Go" to begin.

To make choices of views: select a group. The Red Box that says "Back, leads you to previous menus. Most menu options are self explanatory, so when you need to do something look for the options under the various pull down menus. You can turn off the audio using these menus – or turn down the audio volume on your computer monitor if you wish.

Select the "World View". The program with start running – illustrating where and when earthquakes and volcanic eruptions have occurred around the world. Notice the following:

1. the time scale bar at the bottom left that shows the dates. How many years is represented in this time sequence? _________
2. earthquake and eruption counters keep track of the number of quakes and eruptions over time.
3. How many quakes in this time interval worldwide? _________

How many earthquakes on average each day? __________

 

4. How many volcanic eruptions over the entire time interval? _____________

Once the World View sequence has displayed all the quakes and eruptions up to the present time – click on the "Information" button in the lower right of the map window. Use the information there to answer the following questions:

1. At any particular moment, about how many volcanoes on Earth might be actually erupting lava, pumice or ash? _____________________
2. Remote sea-floor volcanic eruptions at the mid-oceanic ridges are in most cases difficult or impossible to detect. However, what advanced technology is starting to bring sea-floor eruption sites into the realm of study? _____________________

From the "World View" above, select the "Back" button to return to the "World Menu".

Select "North American Group" from the World Menu.

Select "California Group" from the North American Group.

Select "Northridge 1995 Group" from the California menu.

Select "Northridge California 1995". The program will start running.

What is the time interval run for the Northridge quake? __________________

How many quakes occurred in this interval of time? ________________

Note that the default speed of the program runs at 5 hours/sec. Adjust this speed so that the program runs at 1 hour/sec and hit the "Repeat" button. Watch carefully as the time of the quake (Jan 17 04:31) approaches. Were there any foreshocks that might have helped seismologists that a major earthquake was imminent? ____________

In the map view, major earthquake faults in Southern California are shown by the blue lines. Does the main shock of the Northridge quake occur on any of these mapped faults?

Where are almost all of the aftershocks of the Northridge 1995 earthquake located relative to the main shock? ______________

Northridge Cross-Section

From the screen above, select the "Back" button followed by "Northridge Cross-Section". The program will begin – let it run through. This program is showing a cross-sectional view through the Earth which displays the depth distribution of quakes associated with the Northridge event. The default speed is 4 days/sec. Slow this all the way down to 1 hour/sec and play it again – this time examining more closely the pattern produced by the Northridge quake and its aftershock sequence.

At what depth did the main shock occur? ______________

Draw a simple sketch below showing the likely geometry of the fault (note that the shallowest earthquakes DO NOT fall directly on the fault – these are distributed in a group above the fault).

Can you guess what kinds of structures may be associated with the shallowest group of earthquakes?

1. Click on the Alaska Group – which is a subset of the North American Group. Run Alaska 1964 – this is the 2nd largest earthquake in the 20th century. What was the Magnitude of this quake? Briefly describe the pattern produced by the main shock and the aftershock sequence. Estimate the length of the fault rupture – you can do this by consulting one of the maps in the Lab and use the scale to measure the length of the fault.

 

 

 

 

 

 

 

 

2. Click on the Cook Inlet, Alaska view. What can you see in the earthquake pattern that supports the hypothesis that this earthquake population was generated by a subduction zone? (For extra clarification click on Cook Inlet, 3D). Draw a sketch in the space below to illustrate.

Go to the Atlantic Group and then to the Atlantic Ocean View and run the program. You attention is naturally drawn to the great activity along the western edge of South and North America – but try to focus your attention on the Mid-Atlantic Ridge spreading center. Compare the earthquake activity from this mid-ocean spreading ridge to activity from subduction zones – what are the main differences?

1. Select the "Pacific Ocean View".
2. De-select eruptions to simplify the view and set the EQ cutoff to 5.0.
3. Note the total number of earthquakes that occurred in this view over the time interval.
4. Repeat this process with the EQ cutoff set successively to 6.0, 7.0, and 8.0 and enter the data in the table below.

EQ cutoff	Total # of quakes	# of quakes at each magnitude	Log(# of quakes at each magnitude)	Energy – expressed as # of magnitude 5.0 quakes
5.0
6.0
7.0
8.0

5. Recognize that the total number of earthquakes when the EQ cutoff is set at 5.0 includes all the quakes of higher magnitude. If we want to know how many quakes of magnitude 5.0 (strictly speaking - quakes from 5.0 up to 5.9) occurred then we must subtract all the quakes of higher magnitude from this number. This represents the "# of quakes at each magnitude" in column three of the table.
6. On a separate sheet of paper, plot the number of quakes at each magnitude. You will see that this graph is not very easy to read because of the large range of values; some are very large and some are small making it hard to properly view all the data. This is something that occurs very frequently in geological problems. A standard way to deal with this problem is to use logarithms for plotting graphs.
7. Determine the logarithm of the number of quakes at each magnitude and enter these values into the table. Recall that the log of a number is the exponent raised to base 10 that returns the number, ie., the log of 100 is 2 because 10²=100.
8. Now plot Log(# of quakes at each magnitude) vs magnitude on the same piece of paper next to the previous graph and compare the two. Notice that on the log plot is more informative and easier to read since the data are spread more evenly across it. Also notice that the data define a nearly straight line; this is because the decrease in number of earthquakes with increasing magnitude is an exponential function.
9. How much energy is associated with the different magnitude quakes? Since there are so many more magnitude 5.0 quakes it is natural to assume that most of the seismic energy is associated with the smaller quakes. Lets test this idea by converting the number of 6.0, 7.0, and 8.0 quakes into equivalent numbers of 5.0 quakes. An increase in one unit of magnitude is equivalent to an increase of 32 times the energy released. For example, a single magnitude 6.0 quake is equivalent to 32 times the energy of a single 5.0 magnitude quake. So, to compare the amount of energy associated with the 6.0 quakes to 5.0 quakes we must multiply the number of 6.0 quakes by 32. The magnitude 7.0 quakes must be multiplied by 32 x 32 to get the number of equivalent 5.0 quakes in terms of energy release; similarly the 8.0 quakes must be multiplied by 32 x 32 x 32. Determine these numbers and fill in the last column of the table above. Plot the data on a separate sheet of paper to compare the amount of energy associated increasing magnitude. What do you find?