Tues Jan 21
Many Rivers occur along faults
- San Andreas Fault is a very large example
- This is important for building dams along rivers
- Faults create canyons on rivers that are appropriate places to build dams.
Where do earthquakes occur?
Focus: point of energy release on the fault. The pinpoint area with the MOST energy.
Epicentre: the point directly above the Focus that is on the Earth’s surface.
- Closest place at Earth’s surface to the Focus.
Use Seismometer to determine where earthquake occurs and the energy released by it.
Seismometer allows us to:
- Detect the Energy from an earthquake
- Measure distance to an earthquake and locate it
- Measure the energy released during an earthquake
Seismometer looks like a hang man set up, with the person substituted with a large spring with
a block hanging on the end (inertial mass). Pen is attached to mass and touching paper below,
works by being shaken back and forth.
Many times there will be seismometers in both NS and EW directions, as well as vertical pens
for movement in that direction.
How do we find the Focus of an Earthquake