Earthquake Basics

Earthquakes

Earthquake 101: National Geographic

Open Ended

What causes earthquakes?

Open Ended

What is the name of the scale we now use to measure earthquakes?

Open Ended

What are some ways that we protect ourselves from the effects of earthquakes?

Earthquakes

Plate Tectonics

• Recall that the Earth’s

crust is broken into
large pieces called
plates.

• These slowly moving

plates bump into each
other, slide past each
other, or pull apart
from each other.

• This causes much

stress on the rocks.

Earthquakes

Plate Boundaries

• Earthquakes can occur at any of the plate boundaries

•

•

Subduction Zones and Transform Boundaries
result in movement along
fault lines causing
earthquakes and volcanic
eruptions.

Multiple Choice

Which of the following is not a type of plate boundary?

• Transform

• Convergent

• Transvergent

• Divergent

Earthquakes

Earthquakes

• Occurs when the pressure built up along a fault line or
  plate boundary, becomes so great that the rocks on
  either side of the fault
  suddenly rip apart.

• This pent-up pressure is released as energy.

• • Energy radiates out in the form of seismic waves.

Earthquakes

Earthquakes (cont)

•This energy results in
violent shaking, which
sometimes causes great
destruction.

•Small earthquakes
happen frequently, but
large ones are more rare
and difficult to predict.

•Smaller aftershocks occur
after the main event.

Open Ended

What is an aftershock?

Earthquakes

Seismograph

•An instrument that
measures and records
details of earthquakes

•Determines the strength
and the duration of an
earthquake

•Seismogram – the record
produced by the
seismograph

•Seismologist – a scientist
who studies earthquakes

Match

Match the following

• Seismograph

• Seismogram

• Seismologist

An instrument that measures and records details of earthquakes

The record or the earthquake produced by the instrument.

A scientist who studies earthquakes.

• An instrument that measures and records details of earthquakes

• The record or the earthquake produced by the instrument.

• A scientist who studies earthquakes.

Earthquakes
Seismic Waves

●

• Once the energy is
  released during an
  earthquake, it moves through the earth in a series of waves called seismic waves

• There are two main
  types of waves: P
  Waves and S Waves

●

​Seismic Waves

Earthquakes

Seismic Waves

P Waves (primary waves)

•

First waves to arrive at the
seismic station (fastest)

•

Can move through the solid
and liquid layers of the earth

•

Shakes the ground back and
forth (push/pull)

Direction of Wave

Earthquakes

Earthquakes

Seismic Waves

S Waves (secondary waves)

•Slower than P Wave

•Can move through the solid layers
(crust and mantle) of the earth

•Moves rock particles side to side or
up and down

Earthquakes

Multiple Choice

What are the waves called that move through the earth after an earthquake?

• Earth Waves

• Quake Waves

• Seismic Waves

• Large Waves

Multiple Choice

P waves do all the following except...

• Move through solid and liquid layers of the earth

• Shake the ground back and forth (push/pull)

• Are the first to arrive (fastest)

• Move the ground up and down

Earthquakes

Focus and Epicenter

•Focus – the point within
the earth where the
earthquake originates

•Epicenter – the point on
the Earth’s surface
directly above the focus.

Earthquakes

© Kesler Science, LLC

Earthquakes

Determining the
Epicenter

•Scientists use a method
called triangulation.

•It takes 3 seismographs to
locate the epicenter.

•You must determine the
distance each station is
from the earthquake and
draw a circle around each
using the distance as the
radius.

Where the

3 circles
intersect

is the

epicenter.

© Kesler Science, LLC

Earthquakes

Measuring
Earthquakes

•Moment Magnitude Scale:
most commonly used scale
to measure the amount of
damage and strength of an
earthquake

•Numbered from 1-10

•Each increase in magnitude
is actually 32 times greater
in release of energy than
the previous magnitude

•The Richter scale is
outdated and no longer
used, but often referenced

Match

Match the following

• Focus

• Epicenter

• Moment Magnitude Scale

The point within the earth where the earthquake originates

The point on the Earth's surface directly the earthquakes origination

scale used to measure amount of damage and strength of earthquake

• The point within the earth where the earthquake originates

• The point on the Earth's surface directly the earthquakes origination

• scale used to measure amount of damage and strength of earthquake

Earthquakes

Tsunami

•A powerful series of waves generated by an earthquake or landslide under the ocean

•Huge amounts of seawater are displaced.

•Can travel at an average of 450 mph in open ocean

•Can be very destructive to coastal areas

Open Ended

What are 3 things you learned about Tsunami's?