Answer to Question 1
ANSWER: An earthquake on the subduction zone triggers a rapid vertical movement of one side of the fault. The motion can either be a rise or fall of the surface. The seawater above the earthquake is displaced upward or downward. Water flows in order to re-establish sea level, and the disturbance moves outward in all directions.
The effect of the tsunami will be affected by the magnitude of the earthquake, the area of the rupture zone, the rate and volume of water displaced, and the depth of water above the rupture.
Answer to Question 2
ANSWER: A successful answer will include at least four of the following (or equivalent correct statements). All statements must be retrofits of existing structures.
- wood frame houses can be firmly attached to their foundations so that they will not be shaken off of them
- small ground floors of multi-story houses can be shored up to provide support
- reinforced concrete pillars can be sheathed in steel to prevent collapse.
- buildings surrounded by windows can be supported with external diagonal bracing
- base isolators can be placed under existing buildings
- glass can be covered with window film or replaced with safety glass
- building codes can specify that repairs to existing buildings use earthquake-safety features