35.14. Directionality and Peak Acceleration

Try these first

1. 1.

   What is the definition of Peak Ground Acceleration (PGA)?

   Hint

   Think of it as the extreme shaking observed when an earthquake hits.

2. 2.

   What is forward directivity?

   Hint

   Consider how the direction of the fault affects the shaking intensity.

3. 3.

   What does PGA stand for?

   • Peak Ground Acceleration
   • Peak Ground Area
   • Peak Ground Average

   Hint

   Focus on what the term represents in geology.

4. 4.

   True or False: Forward directivity can result in increased PGA.

   • True
   • False

   Hint

   Think about how shaking differs based on the fault direction.

5. 5.

   Consider a scenario where an earthquake has a primary rupture located 5 km from a building. If the recorded horizontal PGA is 0.6g towards the building and 0.4g perpendicular to it, calculate the combined Vector PGA.

   Hint

   You’ll need to apply the Pythagorean theorem here to combine the horizontal components.

6. 6.

   Discuss how neglecting forward directivity can pose risks in urban planning, especially in seismic zones.

   Hint

   Consider what impacts may arise from assumptions made about shaking intensity.