OCEAN 100 LAB 8: Investigation: Tsunami Speeds and Arrival Times
Name:_______Sabrina Ruiz_____
(Modified from http://www.geo.utep.edu/pub/bkonter/education/Lab9_Tsunami_Classroom_Exercise.pdf)
A great earthquake with a magnitude of 9.0 occurred at 00:58:53 UTC, 26 December 2004, and was located off
Sumatra, Indonesia. This earthquake produced a devastating tsunami that was recorded at many worldwide tide
gauges.
Materials: calculator, compass, ruler.
Procedure: Firstly, we’ll have a brief discussion on Tsunamis and wave dynamics.
1. a) Locate Sumatra on the map (Fig. 1). The earthquake is shown with a small star. What do we call this location?
_____________________epicenter_______________________________________
b) What is the tectonic regime in this area?_________subduction tectonics__________________________________
c) What exactly is the cause of the great displacement of the ocean?___________earthquake displacement__________
The speed of a tsunami C (Celerity) in the ocean is computed by the following equation:
where G = gravity acceleration (9.8 m/sec2) and D = depth of the ocean in m
2. The average ocean depth is 3730 m. Let’s use it to compute the average speed of a tsunami. Start with the equation
above and show all steps with their units.
C= sqrt[(9.8m/sec^2)(3730m)] = sqrt36,554(m^2/s^2) = 191.19 m/s
3. This speed is about 700 km/hr (or 500 m/hr). This is comparable to the speed of a:
a. car b. airplane c. fast-speed train d. bicycle
4. Using the speed you computed, compute now the distance traveled by the tsunami in the following time spans,
using: D = V x T. You must show all your work. (Hint: first determine how many sec are in an hour and how many m
in a km, and also convert your speed of km per hour to km per second