28.12.3. Depth of Focus

Try these first

1. 1.

   Define depth of focus.

   Hint

   Think about how deep below the ground the earthquake occurs.

2. 2.

   What depth categorizes a shallow-focus earthquake?

   Hint

   Is it deeper or shallower than 70 km?

3. 3.

   What is the depth of focus for shallow-focus earthquakes?

   • < 70 km
   • 70-300 km
   • > 300 km

   Hint

   Think about the general definition of shallow versus deep.

4. 4.

   True or False: Deeper earthquakes cause more intense surface shaking than shallow ones.

   • True
   • False

   Hint

   Consider the relationship between depth and intensity.

5. 5.

   An earthquake occurs with a focus depth of 75 km. A nearby town experiences significant shaking, while another town 50 km away experiences mild effects. Discuss how depth of focus and distance influenced the observed intensity differences.

   Hint

   Consider how the distance from the epicenter interacts with depth.

6. 6.

   Evaluate the effects of a 65 km depth earthquake on two different soil types: soft and hard rock. Predict the intensity variances and the potential damage each soil type may face.

   Hint

   Think about how deep quakes interact with different soil types.