Exam 3: Earthquake Geology and Seismology

Which of the following wave types travels slowest through rock?

Typically fewer than 20 major and great earthquakes (magnitudes of 7 and higher)each year account for more than 90 percent of the energy released by earthquakes.

Seismic waves that travel only near the Earth's surface are of two main types: _________ waves.

Following the paths of P- and S-waves from the Earth's surface inward,there is an initial increase in wave speed but then a marked slowing occurs at a depth of about 100 feet;this defines the top of the lithosphere.

The Lisbon earthquakes of 1755 are historically significant because ______________.

Flexible buildings (made of wood or steel)have a ________ resonant period than a stiffer building (one of brick or concrete).

The two largest moment magnitudes measured to date are the 1964 Alaska earthquake (M_S of 8.3;M_W of 9.2)and the 1960 Chile earthquake (M_S of 8.5;M_W of 9.5).

Passing through the mantle below the asthenosphere,the seismic wave velocities vary but generally increase until about 2900-km depth where P-waves slow markedly and S-waves disappear at the core-mantle boundary zone.

Earthquake intensity scales such as the Modified Mercalli scale assess the effects on people and buildings.

First-order analysis of a seismogram record allows seismologists to do all but which of the following?

When most of the movement along a fault is horizontal,the fault is referred to as a __________ fault.

Each year,the Earth is shaken by millions of earthquakes.

To describe the location in three-dimensional space of a deformed rock layer or a fault surface,geologists make measurements known as dip and strike.

The reduction of ______ waves at the core-mantle boundary indicates that the outer core is mostly liquid.

The shallower the hypocenter,the more P- and S-wave energy will hit the surface,thus putting less energy into Rayleigh waves.

_________ waves are transverse waves that propagate by shearing or shaking particles in their path at right angles to the direction of advance.

The intensity of an earthquake is influenced by all but which one of the following?

Velocities for _________ waves in granite are about 5.5 to 6 km/sec,but in water they slow to 1.5 km/sec.

The _________ waves' motion is similar to S waves,except it is from side-to-side in a horizontal plane roughly parallel to the Earth's surface.

With their up-and-down and side-to-side motions,S-waves shake the ground surface and can do severe damage to buildings.