# Earthquakes 2012

## 47 terms

### Amplitude

the height of a wave's crest

### Aftershock

an earthquake that occurs after a larger earthquake in the same area.

### Body Waves

these are the s and p waves because they travel through the body of the Earth.

### Compressional Waves

a wave in which the energy travels in the same direction as the wave.

### Crest

the highest point of a wave

### Earthquake

shaking of the Earth's crust due to a release of energy

### Elastic-Rebound

theory that states most earthquakes occur as plates move, get stuck, bend and then break, releasing stored energy

### Epicenter

the point on the Earth's surface directly above the focus of an earthquake

### Fault

a crack in the Earth along which movement has occurred

### Focus

the point beneath Earth's surface where rock breaks under stress and causes an earthquake.

### Foot Wall

the block of rock that forms the lower half of a fault

### Hanging Wall

the block of rock that forms the upper half of a fault

### Intensity

a measure of the amount of damage done to an area by an earthquake

### Liquefaction

when shaking of an earthquake caused saturated solid ground to turn into a liquid like pudding

### L-waves

last wave to arrive, slowest, up and down motion, causes the most damage

### Magnitude

the amount of energy released during an earthquake

### Mercalli Scale

a scale that rates earthquakes according to their intensity and how much damage they cause

### Moho

the boundary between the earth's mantle and crust

### Normal Fault

an inclined fault in which the hanging wall appears to have slipped downward relative to the footwall

### Oblique Fault

a fault where the motion is diagonal. A combination of vertical and strike-slip movement

### P-waves

travels fastest, compressional waves, can travel through solids, liquids and gasses

### Thrust Fault

a reverse fault in which the hanging wall slides over to the foot wall.

### Richter Scale

a scale that rates an earthquake's magnitude based on the size of its seismic waves

### Seismic Gap

an area along a fault where relatively few earthquakes have occurred recently but where strong earthquakes are known to have occurred in the past

### Seismic Moment

a more accurate measurement of earthquake magnitude than the richter scale.

### Seismogram

the paper record of an earthquake's seismic waves produced by a seismograph

### Seismograph

an instrument that records earthquake waves

### Seismology

the branch of geology that studies earthquakes

an area on the Earth's surface where no direct seimic waves from a particular earthquake can be detected.

### Shear Waves

waves where particles of material move back and forth perpendicular to the direction where the wave itself moves

### Strike/Slip Fault

a type of fault where rocks on either side move past each other sideways with little up or down motion

### Surface Waves

seismic waves that travel along the Earth's surface, L-wave

### S-waves

travels slower, side-to-side, shear, secondary, only through solids

### Trough

lowest point of the wave

### Tsunami

a massive ocean wave that forms after a volcanic eruption, submarine earthquake, asteroid or landslide displaces water

### Wavelength

the distance between corresponding points on adjacent waves

### Love Wave

A surface wave (type of L-wave) that causes rocks to move side-to-side. Very Destructive.

### Rayleigh Waves

A surface wave (type of L-wave) that reaches the surface with up and down movement

### Palatine

Name of ship that inspired the legend of the Palatine Lights

### Subduction Boundary

The type of boundary earthquakes are associated with

### 4 causes of an earthquake

volcanic eruption, meteorite impact, nuclear explosion, build up of stress between plates

### 5 sources of earthquake destruction

1. Ground shaking
2. Liquefaction
3. Tsunamis
4. landslides
5. Fire

### 3 reasons fire cause damage during earthquakes

1. gas lines can break causing things to be flammable
3. water lines can break making it hard for fires to be put out
4. collapsed buildings can make it hard for the fire department to get to the fire

### S-P Lag time

The time difference between when the seismograph records the first P-wave and when it records the first s-wave

### The 5 major faults in Massachusetts

Connecticut Valley Border, Wekepeke, Clinton-Newbury, Bloody Buff, Northern Border

### 1755

last major earthquake in Boston

1. Side to side
2. Solid
3. secondary
4. Slow
5. Shear