- Why could the time of day that an earthquake occurs be a major factor in the number of fatalities that results from the earthquake?
Loss of life in earthquakes is usually higher during working hours (i.e., 9:00-5:00) because many people are in large buildings (i.e., schools, factories, office towers, etc.) during that time.
-
What are three other factors that could affect how much damage an earthquake causes?
Other possible factors could include: magnitude, duration, distance from hypocenter (focus), underlying material, design and materials used for structures, and population density.
-
List four other possible causes of damage resulting from an earthquake, other than the direct damage caused by the passage of seismic waves.
Liquefaction, landslides, tsunamis, and fires.
- Why is a tsunami not dangerous in the open ocean over deep waters?
A tsunami has a small amplitude in the open ocean, usually not exceeding 1 meter (3 feet). Most boats will not even remark on the passage of a tsunami underneath them. It is only when the tsunami hits shallow coastal waters that the wave amplitude will increase as the water starts to pile up upon itself.
- Why can fires become a major source of damage as a result of an earthquake?
Gas lines and electrical lines are often severed as a result of earthquakes. The resulting fires can be quite difficult to combat since water mains are also often severed as a result of the same earthquake.
- What are some steps that individuals can take to reduce the hazards from earthquakes in their personal residences?
Individuals can take such precautions as anchoring heavy, movable objects, bracing water heaters, having a wrench handy to turn off the gas, and ensuring that a wood-frame house is anchored to a concrete foundation.
- How does a tuned mass damper reduce vibrations in a large structure?
A tuned mass damper is a large mass that vibrates in a direction to oppose the vibrations that are present in a structure.
- Why is long-term earthquake prediction considered to be reasonably reliable?
It is considered to be reasonably reliable because it is based on long-term historical records, on observing patterns over time, and on long-term measurements and observations. This allows scientists to assign statistical probabilities for earthquake occurrence.
- Why does the USGS consider that an earthquake along the Hayward-Rodgers Creek Fault zone is highly probable sometime in the next 30 years?
This is based on records that show that the average interval between earthquakes in this area is 140 years. Since the last earthquake in this area occurred in 1868, the USGS is predicting that another earthquake is highly probable sometime within the next 30 years.