Strain Rate Models and
Predictions:
Lessons with ArcGIS
Tad Sterling
GEO549
Prof. Holt
5/15/07
Lessons with ArcGis: Models and Predictions
Tad Sterling
Title: Earthquake Predictions
Introduction
The definition of an earthquake is “sudden trembling of the ground” according to
Barron’s Earth Science the Physical Setting 3rd Ed. (Denecke, 2006). In our quest to
make predictions on when and where these events will happen next, we have not yet had
much success. We can, however, make forecasts as to the location of larger earthquakes.
(Ludwin, 2006)
The motivation for this lesson is to impart to the student the importance of using
models in making predictions on where the land we live upon will move and how such
correlations may be used to make simple predictions as to where an earthquake of
magnitude 6 or larger may occur.
In order to do accomplish this lesson, GPS data sets of surface movement around
Southern California provided by William Holt and Glenn Richard of Stony Brook
University will be used in the ArcGIS mapping program. This, along with data from the
National Earthquake Information Center, will be used to predict where a large earthquake
may occur in the future.
Grade level: 9
Performance Objective Given previous background information on earthquakes and
fault movement, the students will be able to use the ArcGIS mapping program to locate
areas that have experienced earthquakes near cities over the past 50 years. They will be
able to correlate this data with the movement of faults and points on the crust marked by
these cities going back 2,500,000 years. With the combination of both of these data sets,
the students will make simple predictions as to where these quakes may occur in the
future. The students will be expected to reach mastery level in these exercises.
New York State Core Curriculum for Earth Science Standards
Standard 1:
Key Idea 1:
The central purpose of scientific inquiry is to develop explanations of natural
phenomena in a continuing, creative process.
Standard 6:
Key Idea 2:
Models are simplified representations of objects, structures, or systems used in
analysis, explanation, interpretation, or design.
Key Idea 5:
Identifying patterns of change is necessary for making predictions about future
behavior and conditions.
Background
The educator should teach this lesson with understandings of the following topics:
earthquakes, modeling, and forecasting. The basics here are required. It is also advised
that the educator take a basic course in the ArcGIS mapping program though a detailed
description of its use as it applies to the lesson that is provided here However, a full
course is not required. It is also suggested that the paper, Quantifying Tectonic Rates in
Southern California by E. Bell et. al. (2006) be read for better understanding of how these
models were derived for use in this modeling program. Additional useful information is
provided online at http://www.eserc.stonybrook.edu/strain/.
As stated earlier, earthquakes are sudden ground tremors. Earthquakes can be
caused by faulting or sudden movements of rock along weak planes called faults. A result
of large earthquakes obviously is property damage and potential loss of life for humans
and other creatures as well. The Richter scale quantifies the severity of an earthquake.
This lab investigates earthquakes of magnitude 6.0 to 7.7 for the years 1950 to the
present. According to www.seismo.unr.edu (2007), mag.6.0 quakes can cause significant
damage to older buildings over a small area whereas “7.0 -7.9” is a “major earthquake.”
that “can cause serious damage over larger areas.”
The aforementioned paper by E. Bell et. al. (2006) discusses modeling for
topography and city and fault movements from 3 million years in the past to predicted
movements in the future. Modeling is the use of computers or statistical analysis on data
in order to produce a visual product that can be used for making decisions or predictions.
Here the models were put into ArcGIS format by Glenn Richard of Stony Brook
University program. In addition, the National Earthquake Information Center data (added
by Tad Sterling) was applied to these models so that simple predictions about where these
quakes can occur can be made.
Forecasting is simply making predictions as to future behaviors of a system
from known past information. In this computer lab, the students will make simple
forecasts as to where earthquakes will occur at future times by looking at the movements
of specific locations. Questions can be raised as to the directions that the quakes may be
moving. See the following section for exercises and further information.
Goals
Here the goal is to enhance the student’s interest in what it is like to be a
scientist. The students will gain basic knowledge of ArcGIS, make observations from
graphical data, interpret these observations, and make simple calculations in order to
make predictions on one of the world’s largest natural hazards. The lesson should
proceed as follows. Before the students arrive at the computer lab, three programs should
be opened on the teacher’s computer and made ready for display via projector or smart
board. The bottom window should have ArcGIS opened. Above this is a movie from B.
Birkes et. al. which demonstrates changes in the topography of Southern California going
back 3 million years with visible differences in velocity from one side of the San Andreas
fault to the other. Lastly, the open window on top should be set on Google Earth and it
should be zoomed directly down on the Capitol Building in Washington D.C. The
projected screen should have the following image.
Fig. 1- The Capitol Building in Washington D.C. Image from Google Earth, 2007
The above image should be visible on the screen as the students enter the room.
They will be asked to sit in pairs at the computers and then be briefly be reminded about
how earthquakes occur from faulting. The teacher should then focus the discussion on the
purpose of this lesson. At this time, the students should be handed a worksheet that they
will need to complete for homework. The students will be reminded about the difficulties
(as presented in an early lesson) on making predictions as to when and where earthquakes
can occur. They will then be told that the government has selected them as a special team
to analyze data gathered by special satellites and put into animated movies about plate
motions in Southern California. Their goal is to try to predict where big quakes will occur
over the next ~2.5 million years into the future.
The students will be briefed on what is expected of them in this mission. First,
they will fly to the west coast to observe these animations. While they are there, they are
to calculate the rates of motion of the North American plate and the Pacific plate. They
will look at cities that are in their modern locations and predict where they are headed.
Lastly, they will be asked to assess where trouble spots will occur in the future.
After the briefing, in order for the students to get the sense that they are traveling,
the teacher should zoom out into space on Google Earth and then down on Southern
California. See the following images.
Fig. 2- Google Earth zoomed out to space. Google Earth, 2007.
On the following page is the image, zoomed back down onto Southern California.
Fig.3- Final Google Earth image of Southern California. Google Earth, 2007.
Immediately after arriving at this new location, Google Earth should be closed
and the Birkes movie should be played. See the following image.
Fig. 4- Opening image from Birkes topography movie going back 3million years.
The students should be asked at this point to observe two different locations on
the movie - one toward the northeast and in the southwest. The teacher should pose the
question to the class, “Which side is moving faster?” When this is answered the teacher
should raise another question about how one area of land could move more quickly in
some locations than others. The answer of course is plate tectonics. The movement of two
different plates, the North American and the Pacific plates causes this phenomenon.
After this discussion is complete, the students should be asked to open up their
ArcGIS files called “Earthquake Prediction”. The teacher can close the movie window,
and the ArcGIS file should already be open on the screen. The teacher should now be
available to assist anyone who may need help in opening this file. The screen should have
the following map made available upon opening the file.
Fig.5- First Map Selected represents southern California 2.5 million years ago showing location of
faults at that time. Note that faults from this time are yellow.
The students will be asked to look at the ArcGIS table of contents on the left side
of their screen and then to turn on various layers by clicking on the boxes next to the
layer names. These layers include city point locations past and present, fault locations
past and present, topography past and present, and the locations of magnitude
earthquakes 6.0 or greater since 1950.
When the students are comfortable with turning on and off the various layers, they
should turn off all of the layers except cities 1 million years ago, topography 1 million
years ago, and faults 1 million years ago. Let the students note some differences in the
images. See the following image.
Fig. 6- Image from 1 million years ago in ArcGIS. Note that faults from that time are blue.
Then the students should turn off all of the layers except present cities, present
topography, and present faults. After this screen is displayed, the earthquake layer should
be turned on. See the following image.
Fig. 7- Present day. Note cities are red, earthquakes are magenta, and modern fault locations are
red.
When the class arrives at this point, the students will be asked to start to gather
data in order to answer questions on the provided worksheet. All students should have the
following map set on their screens: present topography, faults from every time, cities
from every time, and the earthquake layer. See the following map.
Fig. 8- Map of present topography, cites, and earthquakes. The faults are from the present (red), 1
million yrs. ago (blue), and 2.5 million yrs. ago (yellow).
On the following page is the worksheet the students will use to gather all the data
they need and complete the answers for homework. The students should be able to
determine a velocity for a city over the 2.5 million yr. time step. Note the directions that
specific features have moved from, and finally make predictions as to where earthquakes
may occur in the future.
See the following page for the handout.
Name ____________________
Teacher _________________ period ____
Date ______________
Earthquake Predictions
Q1. Which plate is moving faster?
Q2. What cities are located near today’s faults?
Q3. What cities are near earthquake locations?
Q4. Use the measuring tool and fill out the following table.
Measure between
Distance now
Distance 2.5 mill. yrs. ago
Camarillo and Bakersfield
Camarillo and Arvin
Camarillo and Palmdale
In general, do these distances increase or decrease as time moves forward?
Q5. In general, do the earthquakes occur near or far from the faults?
Q6. Calculate average velocity [speed (distance/time) and direction (N, S, E, W, NW,
etc.)] of Santa Clarita from 2.5 million yrs to the present.
From this answer, how far away and in what direction would you predict the nearby
earthquake zone to be 2.5 million yrs. in the future?
On the back of this page write a brief paragraph on how accurate you think your
prediction may be.
Conclusions
In closing, this simple lesson is only a small part of what can be done with the
data available from the work of E. Bell et. al., the ArcGIS mapping program, and Google
Earth. It is meant to get the student’s feet wet and hopefully allow them to see how this
program works and how they may be able begin to address complex scientific problems
with the powerful tools that scientists use.
Some suggestions for future development would be to add the data sets that make
the predictions for the changing land up to 3 million years in the future. It would be
interesting to see how the student predictions compare with those of the computer models
after they have completed them. This lesson is effective without this extension because it
may encourage the students to want to work harder at finding the answers to these types
of questions because at the present there is no known answer available.
References
Bell, E., Holt, W., and Richard, G. 2006. Quantifying Tectonic Rates in Southern
California, MPI Summer Scholar Report, SUNY at Stony Brook Geoscience
Department, Stony Brook, NY. p.1-30
Birkes, B., and Holt, W., 2004, Quantification of tectonic rates using space geodetic and
geologic observations, Mineral Physics Institute Summer Scholars Program final
report, SUNY at Stony Brook Geoscience Department, Stony Brook, NY.
(Movie, 3dneg2)
Denecke, E.J., Barron’s Review Course Series Let’s Review: Earth Science The Physical
Setting 3rd. Ed. Barron’s Educational Series, Hauppauge New York. 2006.
p. 344-345
Earthquake Serverity
http://www.seismo.unr.edu/ftp/pub/louie/class/100/magnitude.html (accessed 5/14/2007)
Google Earth, 2007 used for in text images. (Washington D.C., Earth, and S. California)
National Earthquake Information Center Data for Earthquakes from 1950 to present used
in ArcGIS
http://eqint.cr.usgs.gov
Ruth Ludwin, R.2006. Earthquake Prediction. The Pacific Northwest Seismograph
Network All about earthquakes and geologic hazards of the Pacific Northwest
http://www.ess.washington.edu/SEIS/PNSN/INFO_GENERAL/eq_prediction.
html