Category: Physics in the Universe

Warm Up

Which has more momentum? A huge truck stopped in the parking lot or a bee flying towards you? Explain why.

Classwork

Today and tomorrow and tomorrow we will look at earthquakes.

Today’s video: Japan’s Killer Quake, by NOVA

Https://www.pbs.org/wgbh/nova/videos/japans-killer-quake

As you watch this video, please hold in your hearts the 230,000 people who died from the earthquake and tsunami.

Worksheet assignment

Download File

Other notes from today’s video

• Earthquake ‘P’ waves travel about 1-14 km/sec.
  • P stands for primary since they arrive first.
  • These waves are longitudinal/compressional waves.
• ‘S’ waves travel at about 1-8 km/s, and are the more damaging ones.
  • S stands for shear, but also for secondary (since the arrive second)
  • These waves are transverse waves.
• The earthquake struck about 60 miles off the coast.
• Warnings on all cell phones across Japan. The US is developing this warning system for the west coast.
• In the nuclear power plant that was damaged, nuclear energy (stored in uranium) is converted to thermal energy, then to kinetic energy, then to electrical energy.
• Waves reach Tokyo 100 seconds after the Quake, city had one minute warning. Earthquake lasted for five minutes in Tokyo
• Liquefaction is when moisture in earth is compressed and squeezed out–sort of like squeezing a sponge.
• Tsunami was about 3 feet high, 60 miles in length.
• Tsunami can travel over 500 MPH.
• In the ocean, the wave is not ‘cresting.’ Just like normal waves, they usually crest as they reach short.
• Wavelength of the tsunami was long.
• ‘Miyaku’s high walls are useless’ True or not true?
  • Land dropped up to three feet in some places. This made the walls less useful, but it still decreased the damage.
• Tsunami waves retreat, just like regular ocean waves, and when they do the pull people and debris out with it.
• Tsunami reached Hawaii and surged for over an hour. Wave strong enough to cause major damage, but tsunami warning system allowed people to evacuate.
• As tsunami spreads, energy spreads out and so any particular location receives less energy. Circumference of a circle is 2 π r, so if the tsunami travels 2 times as far, it’s twice as powerful at any one given point on that new circle.
• Aftershocks are less than the original earthquake, but some reach 6.2 since the initial Quake was 9.0.
• Japan’s latitude is about equal to Northern California.
• Formation of hydrogen gas (from water, also creates oxygen), lead to explosions that opened the containment buildings.
• ‘Read to go’ in geologic time can be one second or 100 years.
• Along the west coast, from Washington State to Northern California (near Eureka), the Cascadia fault is a ‘subduction fault’ like that in Japan.
• The rest of California has the San Andreas Fault, which is a ‘strike-slip’ or ‘transverse’ fault; the magnitude of earthquakes on these types of faults is about 10 times less than subduction faults.

Videos of the tsunami reaching North America