Landslide Tsunamis

by Maida CervaniaMr. Leingang’s 6th

Period Science Class

Question

How does the angle at which a landslide falls into a lake affect the size of the wave it creates?

Variables• MV: The angle at which the rocks will

fall (rocks’ velocity)• RV: The size of the wave the rocks

will create• CV: Volume of water, Volume of

rocks, Size of the tub

HypothesisAs I decrease the size of the

landslide’s angle starting at 45 degrees then the size of the wave will increase because the landslide will pick up more momentum at a faster pace.

Materials• 1 plastic tub• Small Rocks (enough to fill the bottom

of the tub)• A flat board• A ruler• Water (enough to fill up half of the tub)• Large Ziploc bag• Tape

Procedure1. Setup as diagram.2. Make sure the container is only filled halfway with

water. Have the ruler taped to the container so that the end of it barely touches the surface of the water.

3. Place the ramp at a 45 degree angle into the water.4. Take the bag of rocks and pour it from the top of the

ramp.5. Record the height of the wave caused by the

landslide.6. Repeat steps 2-5 twice for trials 2 and 3.7. Repeat steps 2-6 twice changing the angle of the

slope to 30 degrees and 15 degrees.

Background Information One of the causes for a tsunami is a landslide which are usually triggered by earthquakes. One of the largest tsunamis occurred in a bay and was caused by a landslide. The wave was over 100 feet and caused massive destruction to the surrounding trees. The simulator used to recreate the incident was placed at only one angle. The wave created was due to momentum. Momentum is measured by an object’s total mass multiplied by the object’s velocity. If either variable is increased, the object’s total momentum is increased as well. If neither variable is increased, then the momentum will not change. Velocity is measured in speed as well as direction meaning even that the velocity of someone running at a 5-mile per hour rate would be 5mph, east or whichever direction the person would be running. Most people mistake velocity and speed for the same thing, but speed has no direction. Changing the angle at which something falls changes the pull that the earth’s gravity has on the object. For instance, if an object falls down a ramp that is completely vertical, it will hit the ground faster than if an object went down a ramp that was tilted.

Angle of Ramp Vs. Height of Wave

Angle of Ramp

Trial 1 Trial 2 Trial 3 Average Height

of Wave

45 degrees

2.0cm 1.8cm 2.1cm 1.97cm

30 degrees

2.2cm 2.0cm 2.1cm 2.10cm

15 degrees

2.5cm 2.8cm 3.1cm 2.76cm

Due to the event that my experiment did not create any waves, the data table below will therefore represent the height of the splashes created by the simulated “landslide”. These measurements are merely an approximation.

Conclusion My hypothesis, which states that as the angle of the

ramp decreases then the height of the wave increases was correct, although rather than waves, the “landslide” created merely ripples on the water, but since both waves and ripples occur impact against the water, I think it should still be able to represent my hypothesis. In my data table, the average height of a ripple created from a “landslide” that fell at a 15 degree angle was 2.76cm. At a 45 degree angle the height of the ripple was 1.97cm. A difference of 0.79cm. This information helps to support my hypothesis. Therefore if we decrease the angle at which an object falls into water then the size of the ripple created will increase.

Abstract The purpose of this project was for me to be able to determine which

areas would be most dangerous in the event of an earthquake that can trigger a landslide. Before I started the experiment, I thought that the size of the wave created would decrease as the angle of the ramp was reduced. During my experiment, I was unable to create a wave. Rather, the rocks that were meant to illustrate a “landslide” created ripples and splashes in the water in the water, though the different angles did change the size of the splashes. Next time I should be more prepared and make sure that the rocks will create a wave rather than take a chance at the last minute and think that it’ll work. Some errors in my project include the amount of water and also the amount of rocks used to simulate a landslide. Thanks to some extra research, I found that I needed a lot more rocks and water in order to create an efficient wave. Also, the overall area needed in order for a wave to even form was a lot more than the tub that I used.