ch16 flashcards

Question 1

quake (earthquake)

Answer 1

A sudden release of energy within the Earth’s crust that creates seismic waves, causing the ground to shake

Question 2

earthquake

Answer 2

A significant seismic event caused by the sudden release of stress along a fault or from volcanic, landslide, or other energetic processes within the Earth

Question 3

elastic rebound theory

Answer 3

The concept that stress builds up in rocks until they reach a breaking point and snap back (rebound) to their original shape, releasing stored energy as an earthquake

Question 4

volcano

Answer 4

An opening in the Earth’s surface through which magma, gas, and ash erupt; volcanic activity can sometimes trigger seismic events

Question 5

landslide

Answer 5

The downslope movement of rock, soil, or debris; large landslides can generate seismic waves that resemble small earthquakes

Question 6

bomb (man-made explosion)

Answer 6

A human-made explosion that can create seismic vibrations similar to small earthquakes, though typically of less magnitude and extent

Question 7

depth of focus

Answer 7

The vertical distance underground at which an earthquake’s energy is released; shallow-focus quakes typically cause more surface damage than deep-focus quakes

Question 8

focus (hypocenter)

Answer 8

The point within the Earth where the earthquake rupture starts and seismic energy is first released

Question 9

epicenter

Answer 9

The point on the Earth’s surface directly above the earthquake’s focus, where the shaking is often felt most strongly

Question 10

fault plane

Answer 10

The surface or zone of weakness along which a fault slip (earthquake rupture) occurs

Question 11

primary (P) wave

Answer 11

A type of body wave that compresses and expands the material it travels through; the fastest seismic wave, arriving first at seismic stations

Question 12

secondary (S) wave

Answer 12

A body wave that moves material perpendicular to its direction of travel; slower than P waves and unable to pass through liquids, arriving second at seismic stations

Question 13

rayleigh (LR) wave

Answer 13

A type of surface wave that moves the ground in an elliptical, rolling motion, causing both vertical and horizontal ground displacement

Question 14

love (LQ) wave

Answer 14

A surface wave that moves the ground side-to-side, horizontally. It typically causes more structural damage due to its shearing motion

Question 15

propagation

Answer 15

The process by which seismic waves travel outward from the focus of an earthquake, passing through and sometimes reflecting or refracting at material boundaries

Question 16

velocity

Answer 16

The speed at which seismic waves travel through a given type of rock or material; influenced by rock density, elasticity, and composition

Question 17

body wave

Answer 17

A seismic wave (P or S) that travels through the Earth’s interior rather than along its surface

Question 18

reflection (seismic)

Answer 18

The bouncing back of seismic waves when they encounter a boundary between materials with different properties

Question 19

refraction (seismic)

Answer 19

The bending of seismic waves as they pass from one material into another with different wave velocities

Question 20

seismograph

Answer 20

An instrument that detects, records, and measures the vibrations produced by earthquakes and other seismic sources

Question 21

triangulation (seismic)

Answer 21

The process of determining an earthquake’s epicenter by using data from at least three different seismic stations and finding the intersection point of their distance circles

Question 22

magnitude

Answer 22

A measure of the amount of energy released by an earthquake, determined by the amplitude of seismic waves

Question 23

local (Richter) scale

Answer 23

An older magnitude scale that uses the amplitude of the largest seismic wave recorded by a standard instrument to estimate the energy released by an earthquake

Question 24

intensity

Answer 24

A qualitative measure of an earthquake’s effects on people, structures, and the natural environment, often recorded on the Modified Mercalli scale

Question 25

ground rupture

Answer 25

The visible breaking and displacement of the Earth’s surface along a fault line during an earthquake

Question 26

creep

Answer 26

Slow, gradual movement along a fault without the sudden release of energy associated with large earthquakes, often preventing significant stress buildup

Question 27

ground shaking

Answer 27

The vibration of the ground produced by seismic waves passing through the Earth, responsible for much of the damage during an earthquake

Question 28

liquefaction

Answer 28

A process where water-saturated soil temporarily loses strength and acts like a liquid due to earthquake shaking, causing buildings and infrastructure to sink or tilt

Question 29

tsunami (seismic sea wave)

Answer 29

A large ocean wave generated by underwater earthquakes, landslides, or volcanic eruptions, capable of traveling across entire ocean basins and causing coastal destruction

Question 30

seiches

Answer 30

Oscillations or sloshing of water in enclosed or semi-enclosed bodies of water (lakes, reservoirs) triggered by seismic shaking

Question 31

fires (from earthquakes)

Answer 31

Secondary hazards often sparked by ruptured gas lines, electrical damage, or toppled fuel tanks following an earthquake

Question 32

aftershock

Answer 32

A smaller earthquake that occurs after a larger main shock, originating near the same fault zone as the main event

Question 33

Mediterranean-Himalayan belt

Answer 33

A major seismic zone extending from the Mediterranean region through the Middle East and Himalayan mountains, known for frequent earthquakes

Question 34

modified Mercalli scale

Answer 34

A qualitative scale that measures earthquake intensity based on observed effects and damage, ranging from imperceptible shaking to catastrophic destruction

Question 35

moment magnitude

Answer 35

A modern, widely used scale that estimates the total energy released by an earthquake, replacing the older Richter scale for large quakes

Question 36

seismic sea wave

Answer 36

Another term for a tsunami, emphasizing its seismic (earthquake-related) origin

Question 37

seismic wave

Answer 37

Waves of energy caused by the sudden breaking of rock within the Earth or by man-made explosions, including P, S, and surface waves

Question 38

seismogram

Answer 38

The recorded trace of seismic waves produced by a seismograph, showing wave amplitude over time

Question 39

surface wave

Answer 39

A seismic wave that travels along the Earth’s surface (like Rayleigh and Love waves), typically causing more damage than body waves due to their larger amplitudes and longer durations