GE 4150- Natural Hazards
Lab 8: Analyze hazards associated with the New Madrid fault zone (Data taken from
Spatial Analysis of Geohazards Using ArcGIS8 by William Harbert)
Synopsis: During the winter of 1811-1812, four great earthquakes rocked the central
Mississippi valley, near New Madrid, Missouri. In recent years, concern has been
growing over the possibility of a similar event hitting the central U.S. This exercise will
analyze the possible effected population as well as interstates, railroads and dams.
Exercise Steps:
1. Copy the exercise data from the class folder onto your h:
2. Open the New_Madrid.mxd located on your h: If necessary set the data source for
your layers by going to your h:
3. You see a map of the U.S. showing the Modified Mercalli Intensities for New Madrid,
Loma Prieta, and Northridge. Notice the large geographic extent for the New Madrid
quake.
4. Add the Quakes5.lyr to your data frame. The layer represents historic earthquakes
greater than magnitude 5.0 since 1800.
5. Add Urban_Areas.lyr. Next we want to determine the names of all of the urban
centers which will experience an intensity of at least VI damage. Select the Urban Areas
that intersect the New Madrid MMI layer. Open the attribute table for Urban Areas.
Choose selected at the bottom. Right click on the DESCRIP field and choose summarize.
Choose DESCRIP as the filed to summarize, save the output as UrbanRisk.dbf on your
h:. Leave all other choices as is and click Ok. Click Yes to add the table to the map.
Open the table. View the urban centers effected, when done close the table.
6. Next we will examine the population effected by the earthquake. Add the Counties.lyr.
Click on the display tab at the bottom of the table of contents. Move the layer below
States48. The counties are symbolized by 2001 population. We want to determine the
number of people for each zone. To do this first open the attribute table for Counties. Add
a new filed and name it Pop_Density and change the type to Double, click Ok. Scroll to
the end of the table and calculate values for Pop_Density. In the calculator type the
expression by choosing the items in the calculator: [POP2001] / [Shape_Area] Now we
have persons per square meter. Close the table.
7. Next we need to overlay counties with the MMI zones. In ArcToolbox expand
Analysis Tools> Overlay> Intersect. Choose to intersect Counties and New Madrid MMI
layers. Save the file as CountyMMI in the NewMadrid.mdb located on your h: Click
finish. The layer shows counties within the MMI zones. Some of the counties are split
between zones. We need to adjust the population to fix this.
8. Open the attribute table for CountyMMI and add a new long integer field called
POP2001ADJ. Calculate the field by using the following expression: [Pop_Density] *
[Shape_Area] Now we have the populations within each zone based on the population
density. Right click on the MMI field and choose Summarize. Choose MMI as the field
to summarize. For summary statistics summarize POP2001ADJ field by its Sum. Name
the table PopMMI.dbf and save the table in the NewMadrid.mdb located on your h:.
Click Ok and add the result to the map. Close the attribute table.
9. Open the PopMMI table. Now we have the total population within each of the MMI
zones. Next we want to show a graph for this data Go to Tools>Graphs>Create New.
Choose to create a Pareto Column Graph (Choose column on the left and the name of
each graph on the right will show up when you click on it). Click next. Choose PopMMI
as the table containing the data. Select the Sum_POP2001ADJ field. Choose next. Name
the graph Population by MMI and label the x-axis MMI field, choose not to show legend.
Click finish. The graph shows the number of people within each MMI zone. When you
are finished with the graph close it.
10. Next we are going to determine interstates which are within the hazard zones.
First let’s change the MMI zones to numbers instead of Roman numerals. Open the
attribute table for New Madrid MMI and add a new field, call the field MMI_num and
choose the type as short integer. We want to have a different number in each field, so the
field calculator will not help us. Leaving the table open, add the Editor toolbar (rightclick in the gray region at the top and choose Editor). From the editor menu choose Start
editing. Choose the location where the NewMadrid MMI layer is stored. A menu will
come and say starting to edit in a different coordinate system, just choose start editing.
Make sure New Madrid MMI is in the target layer. Now going back to the attribute table
input the values in the MMI_num column. Enter values 6-10 corresponding to the roman
numerals (MMI). When you are done close the attribute table. Go to the editor toolbar
and choose Save Edits and then Stop Editing. (Note: The editor toolbar is used to create
new data. You can use the editor toolbar to create point, line, and polygon data for your
hazard project. You can also assign attribute to those new layers.)
11. Add the interstates layer. Vehicle operation is effected at the MMI 8 level. First
select the New Madrid MMI layers which are equal to or above MMI 8 (select on the
MMI_num field). Zoom to the selected features. In ArcToolbox go back to the Analysis
Tools>Extract>Clip. Choose to clip the interstate layer based on the New Madrid MMI
layer, name the file istate_risk.shp. Rename the layer Interstates at Risk. Now we have
the interstates which are completely within the MMI zones above 8.
12. Railroads are bent at an MMI of 10. Do the same steps shown in step 11 but use
railroads and an MMI equal to or above 10. Save the output as rr_risk.shp and rename
the layer Railroads at Risk. When finished turn off interstates and railroads.
13. Add the Dams.lyr from your h:. Select the New Madrid MMI zones which have a
value greater than or equal to 8. Then select features from the Dams layer which are
completely within the selected features of New Madrid MMI (there should be three
features selected). Right-click Dams and choose selection> create layer from selected
features. Rename the layer Dams at Risk and turn Dams off.
14. Save the New_Madrid.mxd on your h:.
Questions: Total of 5 pts (0.5 pts per question)
1. Which major urban area is likely to suffer the most damage?
2. How many urban centers would experience at least a VI level of intensity?
3. How many people live within the MMI zones?
4. What interstates have their center in New Madrid MMI X zone? (Hint: Route_NU)
5. How many dams are within the New Madrid MMI VIII zone?
6. What is the name of the dam located in the New Madrid MMI X zone?
7. Of the dams that are within the New Madrid MMI VIII zone, how many are older than
1950? How will these dams be affected by an earthquake? What are some issues with
the older dams as opposed to the new ones?
8. What is the total population within Arkansas that is within the New Madrid MMI
zones? (Hint: use the fields STATE_NAME and POP2001 in CountyMMI)
9. How many states intersect the NewMadrid MMI zones 8-10? List them.
10. If the New Madrid fault created another 7 magnitude earthquake how comparable
would the damage be to a California earthquake? In what ways would this earthquake
affect the entire U.S.?