Exam 3: Earthquake Geology and Seismology

For magnitudes above about 6,the bigger earthquake magnitude means that more people in a larger area and for a longer time will experience the intense shaking.

The frequency of a wave is __________________.

Earthquake magnitude scales such as the Richter scale assess the effects on people and buildings.

Steno's _____________ states that sediment layers are continuous,ending only by butting up against a topographic high,such as a hill or a cliff,by pinching out due to lack of sediment,or by gradational change from one sediment type to another.

The types of rock or sediment on which a structure's foundation sits are of paramount importance with respect to whether the structure will be damaged by shaking from an earthquake.

Different estimates of earthquake magnitude are derived from different methods based on local shaking (Richter scale),body waves (m_b),surface waves (M_S),or seismic moment (M_W).

With compressional forces,the hanging wall moves upward relative to the footwall;this type of fault is referred to as a __________ fault.

Low-frequency surface waves will be amplified in tall buildings with low frequencies of vibration.

In igneous rocks such as granite,S-waves travel about 1.7 times faster than P-waves.

A normal fault occurs when the hanging wall moves ________ relative to the footwall.

Transform faults have mostly vertical displacement rather than horizontal displacement.

The _________ explains that sediments (such as sands,gravels,and muds)are originally deposited or settled out of water in horizontal layers.

________ faults are commonly found at areas of plate convergence where subduction or continental collision occurs.

P- and S-waves do not follow simple paths as they pass through the Earth;they speed up,slow down,and change direction,and S-waves even disappear when they reach the Earth's core.

Usually,the biggest concern in designing buildings to withstand large earthquakes is the ____________ components of movement.

The high-frequency seismic waves are most energetic for short distances close to the epicenter,whereas low-frequency seismic waves carry significant amounts of energy for much greater distances away from the epicenter.

The __________ is measured in cross-sectional view as the angle of inclination from horizontal of a tilted rock layer,and _______ is viewed in map view as the compass bearing of the rock layer where it intersects a horizontal plane.

It is the horizontal fault movements at subduction zones that most commonly cause tsunami,mostly in the Pacific Ocean.

The point where a fault first ruptures underground is known as the epicenter.

Moving into the core,P-wave velocities gradually increase until a positive jump is reached at about a 5150-km depth,suggesting that the inner core is solid.