EQ1: Tectonic hazard formations & risks

Question 1

What causes an earthquake?

Answer 1

• At a covergant boundary, the denser (usually oceanic) plate is forced under the lighter (ususally contiental) plate. The plates often get stuck at the beneioff zone, creating massive amounts of friction and pressure
• As they jolt past each other, this energy is rapidly released in the form of siesmic waves
• A large fault is produced and one plate usually uplifts rapidly

Question 2

What is the difference between P waves and S waves?

Answer 2

• P (primary) waves cause the intital shock, they shake the ground vertically.
• S (secondary) waves come after and sake the ground horizontally. These cause signaificantly more damage.