Home > Earthquakes > Concept #4 Quiz
type of surface material present earthquake proximity to a populated area earthquake duration time magnitude of the earthquake distance to the epicenter
Match the terms with the most appropriate type of destruction with which they are associated: [Hint]
Using the pulldown boxes, match each item on the left to the corresponding item at right.
sand and mud / bedrock – sand and mud will better transmit the energy of the waves without collapse, but rocks cannot withstand the shaking without collapse. water-saturated sediment / bedrock – sediment better transmits the energy of the waves without collapse, but rocks cannot withstand the shaking without collapse. bedrock / unconsolidated sand – rocks better transmit the energy of the waves without breaking, but unconsolidated sand cannot withstand the shaking without collapse. unconsolidated moist soil / unconsolidated sediment – soil better transmit the energy of the waves without collapse, but sediment cannot withstand the shaking without collapse.
Tsunamis are faster than seismic surface waves. Tsunamis cause the land to ripple and oscillate. Tsunamis have relatively small amplitudes compared to their very long wavelengths. Tsunamis are easily seen at sea but are lost in the swell and breaking waves along the coast.
The seafloor suddenly moves upward or downward during an earthquake, displacing the sea surface into a mound or trough, initiating a tsunami. The seafloor undergoes sudden horizontal slippage during an earthquake, causing the overlying water to be accelerated or pushed laterally, initiating a tsunami. Tsunami are only serious threats to coastal areas near an earthquake epicenter because the waves have lost most of their energy after moving across 100 miles of open water. Tsunami lose little of their energy moving long distances through open water, so they can present serious threats to coastal areas hundreds of miles from the location of the initiating earthquake.
Tsunami are only violent during the time between high and low tide, therefore they cannot be “tidal.” Tsunami are generated solely by earthquakes, not by the influence of the gravitational pull of the Moon and the Sun. Tsunami are generated only sometimes by the influence of gravity between the Moon, Sun and Earth. Tsunami are generated solely by the gravitational pull along faults between the Earth, the Moon and the Sun.
Tsunami occur by fault-induced, vertical shifts in the sea floor that suddenly propel great masses of water downward. Tsunami wave heights decrease and wavelengths increase as they move into shallower water. Tsunami travel as deep-water waves at speeds greater than surface seismic waves but are slower than S waves. Tsunami are started by fault-induced, horizontal shifts in the sea floor that suddenly propel great masses of water in opposite directions.
wavelengths are so long that they appear as soft, smooth, and gentle waves wave heights are so long relative to the wavelengths so that they appear only close to the shore wave heights are so short relative to the wavelengths that they do not appear severe until they reach shore wavelengths are so short that they appear and break too close to the epicenter
Buildings were constructed on unconsolidated, water-saturated lakebeds and foundations failures are common. The earthquake epicenter is directly in the center of the most populated area, causing the largest shaking in that spot. Numerous poorly-constructed, top-heavy, concrete-slab buildings will almost always fail during even the smallest earthquakes. An earthquake hitting at "rush hour" causes motorists to be killed when freeways collapse.
