Earthquake Anatomy
What is the point underground where an earthquake begins?
Focus
What are seismic waves?
Energy waves released during an earthquake
What scale measures earthquake magnitude?
Richter Scale (or Moment Magnitude Scale)
What are tectonic plates?
Large pieces of Earth’s crust
Which is safer during an earthquake: a wide building or a very tall, narrow building?
A wide building
What is the point on Earth’s surface directly above the focus?
Epicenter
Which wave arrives first: P waves or S waves?
P Waves
What does magnitude measure?
The energy released
What type of boundary causes earthquakes in California?
Transform Boundary
Why are buildings with a low center of gravity more stable?
They are less likely to tip over.
What is a fault?
A crack in Earth's crust where plates move.
True or false: There is only one seismic wave station around the world.
False, there are many.
Which is stronger: magnitude 6 or magnitude 4?
Magnitude 6
What fault runs through California?
San Andreas Fault
Which material is usually better in earthquakes: rigid brick or flexible steel?
Flexible steel (flexibility absorbs energy)
What causes most earthquakes?
Movement of tectonic plates.
How many seismic waves station does it take to locate an earthquake?
at least 3
Is the Richter scale linear or exponential?
exponential
What happens at a convergent boundary?
Plates push together
Why are buildings built on solid bedrock usually safer than those built on soft soil?
Bedrock shakes less and is more stable than loose soil.
Why do earthquakes usually happen near plate boundaries?
Plates are pushing, pulling, or sliding past each other.
What is the technique used to find an earthquake using seismograph stations?
triangulation
How much stronger is a 6.0 compared to a 5.0?
10 times stronger
Why do earthquakes sometimes cause tsunamis?
Underwater plate movement displaces water
Why are unreinforced brick buildings more dangerous in earthquakes?
Brick is brittle and can crack or collapse easily.