This lesson is intended to help students learn about how earthquakes are measured, and the difference of varying intensities. Students will make associations between the modified Mercalli intensity scale and the Richter magnitude scale.
Two class periods depending on what you choose to emphasize.
Students will understand the differences between the Mercalli and Richter scales, and the use of each.
On the first page of the worksheet have students figure out how tall a skyscraper would be if it were 10 times taller than the five-story apartment building. If the skyscraper is 10 times taller than the apartment building, and the apartment building is 10 times taller than the person, how much taller than the person is the skyscraper? On the second page of the worksheet students are asked to figure out the salaries of two of their friends in comparison to their own, see the relation of someone’s salary being 10 times more than their own, and 100 times more than their own.
Explain that earthquake damage involves many topics, three of which are:
In another lesson we will discuss another aspect involved in earthquake damage—structure of area.
Using the animation available on the following website, discuss with students the three types of plate boundaries described in the table 1.
|Convergent||Push towards each other||Appalachian Mountain Ridge, The Alps, The Himalayas||There are two actions here, either one plate can be submerged under another, or the two can push up against each other.|
|Divergent||Pull away from each other||Mid-Atlantic Ridge||As the plates pull apart, lava from the mantle rises to the ocean floor and solidifies, creating new land in the process.|
|Transform||Slide past each other||California coast line||The plates grind past each other, sometimes slipping suddenly causing an earthquake.|
|Richter||Mercalli||Description||Number each year|
|1 & 2||I||Usually not felt by humans, though animals can get uneasy, detected by instruments.||900,000|
|II||Felt by some people, though few, especially if on upper floors. Hanging objects can sway back and forth.||30,000|
|3||III||Felt indoors, though some may think it’s a passing vehicle. Parked cars may rock.||30,000|
|3||IV||Windows, doors, and shelves are disturbed. Felt indoors.||30,000|
|4||V||Felt by most everyone. Furniture moves. Cracked walls. Trees and poles may shake. Pictures fall off walls. Some people awake to it.||30,000|
|5||VI||Felt by everyone. Some furniture falls over. Some damage. Difficult to stand. Windows may crack. Some plaster falls. Chimneys may be damaged slightly.||30,000|
|5||VII||Poorly constructed buildings are severely damaged. Some walls may fall. Some people fall over. Damage to well constructed buildings as well, though moderate at most.||500|
|6||VIII||Moderate to major damage. Walls and chimneys collapse. Heavy furniture falls over.||100|
|7||IX||Many people panic. All buildings suffer major damage, some collapse. Dams crack. Landslides. Ground noticeably cracked. Pipes break. Buildings shift off foundations.||20|
|7||X||Major damage. Landslides. Railroad lines are bent. Roads crack. Structures destroyed.||20|
|8||XI||Total damage. Bridges destroyed. Wide cracks in the ground. Ground surface waves seen. Buried pipes break.||One every 5-10 years|
|8||XII||All manmade structures are destroyed. Ground surface waves seen. Objects thrown into the air.||One every 5-10 years|
Compiled from the following sources:
The third part that determines how much destruction of an earthquake is where it occurs. Ask students to speculate which would be worse, an earthquake of magnitude 7 in the middle of the desert, or an earthquake of magnitude 4 in the middle of a major metropolis.
One thing scientists do is determine where the center of the earthquake is (known as the epicenter). This is done by manner or triangulation, or in other words, if you know how far from 3 different locations the epicenter is, you can find the earthquake. Use the accompanying worksheet titled Find that Earthquake! This activity can also be done on Geometer’s Sketchpad.
Triangulation to find the location of something is used not only in seismology, but also in tracking where a cell phone is when being used off of three reception towers, and when using a GPS system in a car. In the final case the location of the vehicle is determined from at least three satellites in the sky.
Students will be assessed by use of observation of individual and group work during the worksheets and class discussion of the different earthquakes and the damage they caused.
Find that Earthquake! Worksheet
Information on Modified Mercalli and Richter Scales:
Information on Hawaii and Afghanistan earthquakes: