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Assessing Local Earthquake Risks -- Created by Corey Shalanski

Most earthquakes occur along the edges of Earth's tectonic plates where most faults are found. But faults may be found far from the plates' edges as well. Has your region ever been hit with strong earthquakes? The answer may surprise you.

In this activity, you'll take a look at the earthquake hazard risk where you live. You'll also visit the National Geophysical Data Center to find out about earthquakes that have occurred in your region over the past 350 years. Then you'll learn where earthquakes have hit in the United States in the past week.

1.        To begin, view a USGS map of United States earthquake hazards (http://eqhazmaps.usgs.gov/graphics/usmap.jpg).  Look at the color scale indicating the relative hazard from highest to lowest.  A close-up view of New York State can be found at http://neic.usgs.gov/neis/states/new_york/hazards.html

Describe the earthquake hazard for New York.  How does it compare to hazards in other parts of the country?

2.        Where and when were the largest earthquakes to hit your region?  What was their magnitude?  To find out, go to the U.S. Earthquake Intensity Database (http://www.ngdc.noaa.gov/seg/hazard/int_srch.html).  Scroll down to Earthquake Parameters.  For beginning date, enter 1638.  For ending date, enter 1985.  Continue scrolling to Earthquake Magnitudes.  Enter a Minimum Magnitude of 5.0 and a Maximum Magnitude of 9.9.  Scroll to City and State Parameters to select your state.  Click Search Database at the bottom of the page.  Your search should return data on all earthquakes of magnitude 5.0 and greater in the region now bounded by your state from 1638-1985.  The magnitude of each quake can found under the heading "Mag."  The heading "MMI" represents the Modified Mercali Intensity, a measure of how strong an earthquake actually feels.  What are the five strongest quakes (by magnitude) that have hit your region?  In the table below, enter the date, magnitude, MMI, and location (don't list all cities hit by each quake; just describe the general region such as "San Francisco Bay area" or "northwestern Colorado") for each.

3.        Have there been any earthquakes within 100 miles of where you live?  If so, when and where did they occur?  What were their magnitudes?

4.        Go to the following webpage: http://www.ldeo.columbia.edu/LCSN/big-ny-eq.html

When was the largest earthquake in New York City’s history?  When was the most recent large earthquake near New York City?

5.        To see where the most recent earthquakes have been in the United States, visit the USGS Earthquakes Hazard Program (http://earthquakes.usgs.gov/).  Look at the map, then go to the List of Recent Earthquakes (http://earthquakes.usgs.gov/recenteqsUS/Quakes/quakes_all.html).  In the table below, list the five largest earthquakes of the last week, including their location and magnitude.

Go to the Recent Northeast Region Significant Earthquake Report (http://pasadena.wr.usgs.gov/shake/ne/index.html).  How close were any of these events to your home?  Is your home at a significant risk for earthquake damage?  Recall the prediction you made earlier about your local earthquake risk – do you still agree with this statement?  Why or why not?

6.        Based on the information you have gathered, compose a statement about local earthquake risks.  Imagine that you are addressing residents in your neighborhood and wish to inform them about the possibility for earthquakes in your area.  How would you advise them?