Global GIS Lesson:
Exploring North American Earthquakes
By Joseph J. Kerski
Part 3: Investigating the Loma Prieta Earthquake
In this part, you will investigate one of the worst earthquakes ever
to strike the United States, assess critical infrastructure, and assess
the relationship of fault lines to earthquakes.
The USGS has indicated that your report needs to include an analysis
of the following earthquake: In October 1989, as over 62,000 fans filled
Candlestick Park for the third game of the World Series baseball game
and millions of San Francisco Bay Area workers were commuting home,
a major earthquake struck. This was the Loma Prieta Earthquake, damaging
many neighborhoods in San Francisco and Oakland, and collapsing a major
portion of an interstate highway in Oakland, killing many of the drivers.
Make themes you have been working with the active theme by clicking
once on it. Use shift-click to select multiple themes. Clear any previous
Open the earthquake table .
the table to find the Loma Prieta earthquake by its date and magnitude,
as follows. Be sure to enter the information by clicking on the field
names and equals sign.
Zoom to the Loma Prieta epicenter at a scale of 1:1,000,000. The scale
is in the upper right of the map. You can type in the exact scale as
1000000 if you wish in the scale box.
- In what part of California did this earthquake occur?
- Use the identify button
with the US Counties theme active to answer the following: In what
county did the earthquake occur?
- What direction from San Francisco was this earthquake’s epicenter?
- Use the measure tool ,
answer the following. How far was the epicenter from San Francisco?
- Based on what you just measured, discuss how an earthquake occurring
many miles from San Francisco and Oakland could have caused damage
in those cities.
- Earlier, you considered the disruption that earthquakes pose to
critical infrastructure. Turn on the airfields theme and name the
nearest airfield to the earthquake.
- Use the measure tool
to measure the distance to this airfield.
- Find the airfield at latitude 37.36 north and 121.93 west, the
nearest international airport to the epicenter. What city is the airport
- Have you ever flown into this airport? Ask to find out if any of
your classmates have flown into this airport.
- Make roads, railroads, and utility lines visible. Make at least
four observations about the proximity of these features to the earthquake.
- Have other earthquakes occurred in this area of California, or
was the Loma Prieta earthquake an isolated case?
- Turn on the US Faults theme and discuss the relationship between
earthquakes in this part of California and fault lines.
- Based on your investigations, indicate in your report to the USGS
what you consider to be the two main reasons why this earthquake in
October 1989 caused more damage and death than others in this area.
- Do some research on the Loma Prieta earthquake and indicate your
- How does your research enhance what you learned about Loma Prieta
Next, you will examine faults in relationship to earthquakes throughout
Turn off all themes except faults, Alaska faults, US faults, earthquakes,
and the shaded relief base.
Zoom out to all of North America using the globe symbol on the Global
GIS Tools menu.
It is difficult to detect the relationship of earthquakes and faults,
because of the large number of earthquakes. Reduce this number by clicking
on “earthquake tools” in your Global GIS window. Show magnitudes
between 6 and 9, as follows:
- Describe the relationship between fault lines and earthquakes. Consider
these questions in your narrative: Do earthquakes usually, or always
occur near fault lines? Do earthquakes ever occur away from fault
lines? If so, where? Do you think this map shows ALL of the faults
in North America, or just a few? How does this affect your answer?
- Turn on earthquakes between 4 and 9, instead of 6 and 9. Does this
affect your answer, above? Why or why not?
- Turn on cities. Discuss the relationship between cities and fault
lines for your report to the USGS.
- Congratulations! You have completed the third part of the assignment
and have contributed much to the understanding of earthquakes in North
America. Indicate what you consider to be the most surprising
thing you have learned in this part, the most interesting thing,
and the most significant thing.