EARTHQUAKES

Earthquakes

Occur when tectonic plates move. It is a sudden shaking of the plates in the crust.

Ex. (earthquakes)

9.5 in Chile – 9.2 in Alaska – 9 in Japan

Parts of Earthquake (4)

Focus – Epicentre – Faultline – Seismic Waves

Focus

The point where the earthquake begins (in mantle)

Epicentre

Directly above the focus

Fault Line

Long deep cracks in the crust that separate plates

Ex. (fault line)

San Andreas Fault

Seismic Waves

Shockwaves and Tremors

P Waves

First jolt comes from primary

S Waves

Slower + stronger. Secondary

Surface Waves

Trapped near Earth’s surface. Cause severe damage to infrastructure.

Seismic

Caused by an earthquake or vibrations inside the Earth

Seismologist

Someone who monitors and predicts earthquakes

Seismographs

Measures intensity of quake

Richter Scale

Measures the size of quake (up to 10)

Mercalli Scale

Measures visual damage and cost

Tsunamis

Large se wave caused by underwater earthquakes or volcanic eruptions

Ex. (tsunamis)

2004 Indonesian Tsunami - 1958 Alaska

Subduction

One plate sinks under another at convergent boundary

Pacific Ring of Fire

A tectonic belt of volcanoes and earthquakes surrounding most of the Pacific Ocean

Countries in Pacific Ring of Fire

Philippines – Japan – New Zealand