chapter 3

Question 1

what is plate tectonics?

Answer 1

a theory that states the Earth’s crust is separated into plates or pieces that move

Question 2

what are plate boundaries and why are they so important? give example of all 3 types

Answer 2

because this is where most geological processes and many hazards are found. CONVERGENT, DIVERGENT AND TRANSFORM

Question 3

what is an earthquake?

Answer 3

shaking of the ground caused by a release of energy inside the earth.

Question 4

where do most earthquakes occur?

Answer 4

at plate margins (plate boundaries) especially at convergent and transform plate margins

Question 5

what are period, frequency, wavelength, and amplitude?

Answer 5

The period of a wave is the time it takes to complete one cycle. The frequency is just the opposite; it’s the number of wave cycles that are completed in one second. Amplitude and wavelength are both measures of distance. The amplitude measures the height of the crest of the wave from the midline.

Question 6

what is a S wave?

Answer 6

Secondary waves have a slower speed. these waves cause objects to move up and down.

Question 7

what is a body wave?

Answer 7

is an energy wave that travels through the Earth.

Question 8

what is a surface wave?

Answer 8

is an energy wave that travels through the surface of the Earth

Question 9

what is a seismograph?

Answer 9

a sensitive instrument used to measure ground motion

Question 10

how do the velocities of L and S waves differ from one another?

Answer 10

Seismic waves can be distinguished by a number of properties including the speed the waves travel, the direction that the waves move particles as they pass by, where and where they don’t propagate. … The first two wave types, P and S , are called body waves because they travel or propagate through the body of Earth.

Question 11

what is the difference between stress and strain?

Answer 11

strain is how an object responds to stress. stress is the unequal application of force compressive stress

Question 12

how does a seismograph work?

Answer 12

Seismographs can detect quakes that are too small for humans to feel. During an earthquake, ground-shaking seismic waves radiate outward from the quake source, called the epicenter. Different types of seismic waves travel at different speeds and through different parts of the Earth during a quake

Question 13

what os the elastic rebound theory?

Answer 13

when rocks break they sometimes do it elastically. elastic strain is when a rock bends when subjected to a farce and then returns to its original shape when the force is removed

Question 14

what is a normal fault and what causes it?

Answer 14

Tensional stress is when rock slabs are pulled apart from each other, causing normal faults. With normal faults, the hanging wall slips downward relative to the footwall.

Question 15

what is a reverse fault and what causes it?

Answer 15

the reverse of normal faults, because in this case, the hanging wall slides upward relative to the footwall. Shear stress is when rock slabs slide past each other horizontally.

Question 16

what is a strike-slip fault and what causes it?

Answer 16

faults are similarly caused by horizontal compression, but they release their energy by rock displacement in a horizontal direction almost parallel to the compressional force.

Question 17

what is a quick clay?

Answer 17

a clay mineral is a silicates mineral that has a very high surface area to volume ratio. it is make up of sheets that are pieces of paper.the surface areas of clay minerals are also electrically charged which allows clay minerals to store other electrically charged atoms or molecules on their surfaces

Question 18

what factors affect stress and strain in a rock body?

Answer 18

under stress a rock body will either bend (folds) or break(faults)
composition- the # and type of different minerals
texture- the size, shape, and peaking of crystals or grains

Question 19

what are the limitations of the Mercalli Intensity Scale?

Answer 19

it may rely only on local features that are not always found everywhere. for example, no all houses are built the same everywhere.

Question 20

how does bedrock composition, structure and temperature affect earthquake energy?

Answer 20

1. solid rock will transmit energy much better than loose sediment.
2. igneous intrusive (solid, course crystalline) rock and metamorphic rock transmit energy better then sedimentary rock
3. rocks with fewer weaknesses such as faults fracture and bedding planes will transmit energy better than rocks with these weaknesses
4. rocks that are colder, and therefore more solid, will transmit earthquake energy than hotter, less solid rock.

Question 21

Explain the events of Jan 9, 1965 near Hope, BC

Answer 21

a large landslide took place in the Coast Mountains. a large mass of rock fell from Johnson Peak. the exposed igneous and metamorphic rock was weathered, unstable and sitting @ a steep incline
wet, water saturated conditions @ the time and the earthquake in the area triggered this event