Wave generation of tsunami

Velocity of tsunami in the ocean

• Note that the velocity is directly dependent on the water depth D.

• The universal gravitational constant g is present

• This equation simply says that tsunami travel faster in deeper water

Sources for tsunami generationCircles and ovals show areas of high tsunami generation

Which plate boundary settings would cause tsunami and why?

Epicenter of 1964 Great Alaskan EQ

Epicenter location Isoseismal map

Magnitude 8.1 EQ in Alaska 1946

Deployment of detection buoys

How buoys work

Japan EQ and tsunami Mar 11,2011

• Mw = 9.0 (4th largest ever recorded)• Thrust faulting along subduction zone of Pacific and North

American plates• Upward thrust estimated at 30 to 40 meters• Fault movement of about 300 km along strike and 150 km

down-dip direction• Large foreshocks two days before• Area has seen nine events Mw > 7 since 1973• Dead and missing > 20,000• Nuclear power plant lost power so cooling could not continue,

thus resulting in shutdown and possible meltdown

Epicenter location for Japan Mar 11 2011 EQ

Tsunami overwash Mar 11 2011

Source: theatlantic.com

Video of 2011 tsunami

• http://www.youtube.com/watch?v=TRDpTEjumdo

Sample questions

• A tsunami would be most destructive along which type of shoreline? (a) one with a steep seafloor, (b) one with a gently sloping seafloor, (c) both a steep and gentle seafloor would produce the same result.

• TRUE-FALSE. Areas in the open ocean, such as Hawaii, do not experience tsunami. (a) True, (b) False.

• Explain the difference between a distant and a local tsunami.