Download Earthquake Research Assignment

EARTHQUAKE RESEARCH
NAME: _____________________________________
DATE: _______________________________
Vocabulary you should know:
1. Earthquake: a sudden and violent shaking of the ground as a result of a sudden release of
energy in the Earth’s crust that creates seismic waves.
2. Amplitude: size of the waves on an earthquake recording; measured from still reading to the
top of the crest.
3. Distance: the difference in time between the S-wave arrival time and the P-wave arrival time is
a measure of the distance of the seismograph from the earthquake epicenter.
4. Magnitude: a number that characterizes the size of an earthquake by measuring the motions
recorded by a seismograph and correcting for the distance to the epicenter of the quake
5. Focus: the point within the earth where an earthquake rupture starts
6. Epicenter: the point on the earth’s surface vertically above the focus of an earthquake
7. intensity: the effect of an earthquake on the Earth’s surface
8. plate boundary: the locations where two tectonic plates interact; boundaries can be
convergent (coming together), divergent (spreading apart), or transform (sliding past each
other)
9. Modified Mercalli Intensity Scale: scale with 12 increasing levels of intensity to evaluate the
effects of earthquakes; developed in 1931 by Harold Wood and Frank Neumann, American
seismologists
10. Richter magnitude scale: (often shortened to Richter scale) scale that assigns a single number
to the energy released during an earthquake; developed in 1935 by Charles Richter; does not
express damage- just magnitude; relates amplitude to distance (S minus P arrival times)
11. Moment Magnitude scale: scale developed in 1979 by Tom Hanks and Hiroo Kanamori;
replaced Richter scale for large earthquakes; scale considers the distance that rock slides along
a fault surface, the area of the fault surface that is actually broken by the earthquake, and how
rigid the rocks are near the broken fault.
12. Foreshocks: relatively smaller earthquakes that precede the largest earthquake in a series
13. Aftershocks: smaller earthquakes that follow the largest shock of an earthquake sequence
14. Subsidence: the gradual caving in or sinking of an area of land
15. Seiche: a temporary disturbance in the water level of a lake; when water sloshes back and
forth as a result of seismic activity
16. Scarps: a very steep bank or slope
Instructions: Go to the following web address:
http://earthquake.usgs.gov/earthquakes/map/
Zoom out so that you can see all earthquakes that have occurred around the world.
*****Answer the following questions about recent earthquakes around the globe.
Questions About the Earthquakes
1. Orange dots are earthquakes that occurred today. Red dots are earthquakes that occurred in the
past hour. How many earthquakes occurred today? Did any occur in the past hour?
2. The larger the dot, the greater the magnitude of the quake. Click on one of the largest dots on the
map. Which location suffered the highest level of damage? What was its MMI (Modified Mercalli
Intensity Scale)?
3. Click on a dot representing a recent earthquake. Tell the date, MMI, and depth of the quake.
4. How many of the earthquakes that occurred today fell on or near a plate boundary?
Questions about Montana’s Earthquake History
*****Read the USGS (United States Geological Survey) article on Montana’s Earthquake History
and then answer the questions below.
5. Since 1925, how many earthquakes has Montana experienced with a MMI of VIII or higher?
6. In what location have most of these quakes occurred?
7. What is the primary reason that there are so few deaths associated with such large quakes in
Montana?
8. The first significant 20th century Montana earthquake occurred on June 27th, 1925 and was a
magnitude 6. Which towns experienced the greatest damage in this quake?
9. Why did the schools in Helena and the Three Forks area sustain the greatest earthquake damage?
10. How many earthquakes have shaken Montana since 1931?
11. Name the 3 Montana counties that have the highest risk of earthquakes.
12. Where was the largest earthquake in Montana’s history located? What was its magnitude? In what
year did it occur?
13. Name three effects of this massive earthquake.