Earthquakes and Volcanos Earth Science Mr.McKay

Earthquakes Earthquake – The shaking and trembling that results from the sudden movement of part of the Earth’s crust Pebble in pond Scientists predict over 1,000,000 earthquakes happen each year Faulting is most common reason for Earthquakes San Andreas Fault Fault Video

Earthquake – The shaking and trembling that results from the sudden movement of part of the Earth’s crust

Pebble in pond

Scientists predict over 1,000,000 earthquakes happen each year

Faulting is most common reason for Earthquakes

San Andreas Fault

Fault Video

Tsunamis Tsunami- A huge wave caused by an earthquake on the floor of the ocean They can travel at speeds of 700 to 800 MPH They can reach Heights of 20 meters The height of a 6 Story Building Tsunami Off of Thailand Trouble in Paradise

Tsunami- A huge wave caused by an earthquake on the floor of the ocean

They can travel at speeds of 700 to 800 MPH

They can reach Heights of 20 meters

The height of a 6 Story Building

Tsunami Off of Thailand

Trouble in Paradise

Seismic Waves Earthquake waves are known as seismic waves Focus - The point beneath the Earth’s surface where rocks break and move The focus is the point of origin for the earthquake Epicenter - Directly above the focus on the Earth’s surface Earthquake waves reach the epicenter first Seismic Waves

Earthquake waves are known as seismic waves

Focus - The point beneath the Earth’s surface where rocks break and move

The focus is the point of origin for the earthquake

Epicenter - Directly above the focus on the Earth’s surface

Earthquake waves reach the epicenter first

Seismic Waves

Seismic Waves Primary waves- P-waves: Seismic waves that travel the fastest They arrive at a given point before any other type of wave They travel through Solids Liquids Gases

Primary waves-

P-waves: Seismic waves that travel the fastest

They arrive at a given point before any other type of wave

They travel through

Solids

Liquids

Gases

Seismic Waves Primary waves- They move through the Earth differently depending on the material they are traveling through As they move deeper into the Earth, where it is more dense, they move faster They are push-pull waves

Primary waves-

They move through the Earth differently depending on the material they are traveling through

As they move deeper into the Earth, where it is more dense, they move faster

They are push-pull waves

Seismic Waves Secondary Waves S-Waves – Seismic waves that do not travel through the Earth as fast as P-waves do S-waves arrive at a given point after P-waves do S-waves travel through solids but not liquids and gases

Secondary Waves

S-Waves – Seismic waves that do not travel through the Earth as fast as P-waves do

S-waves arrive at a given point after P-waves do

S-waves travel through solids but not liquids and gases

Seismic Waves Surface Waves L-waves: They are the slowest moving seismic waves They arrive at a given point after P and S waves They start at the epicenter and move along the Earth’s surface Earth’s surface moves up and down like water waves do They cause the most damage to the Earth because they bend and twist the surface

Surface Waves

L-waves: They are the slowest moving seismic waves

They arrive at a given point after P and S waves

They start at the epicenter and move along the Earth’s surface

Earth’s surface moves up and down like water waves do

They cause the most damage to the Earth because they bend and twist the surface

Seismograph Seismograph – An instrument that detects and measures seismic waves Crude Seismographs around for hundreds of years The first practical was made in 1893 by John Milne Consists of A weight attached to a spring or wire A pen attached to the weight that records the movement of the Earth on a paper, that is wound tightly around a constantly moving drum

Seismograph – An instrument that detects and measures seismic waves

Crude Seismographs around for hundreds of years

The first practical was made in 1893 by John Milne

Consists of

A weight attached to a spring or wire

A pen attached to the weight that records the movement of the Earth on a paper, that is wound tightly around a constantly moving drum

Seismologists – Scientists who study earthquakes PSP Seismograph They can determine the strength of an earthquake by studying the height of the waves They look at a Seismogram They match the seismogram to a chart called the Richter Scale Invented in 1935 The scale is from one to ten, with any earthquake above 6 being very destructive Seismograph

Seismologists – Scientists who study earthquakes

PSP Seismograph

They can determine the strength of an earthquake by studying the height of the waves

They look at a Seismogram

They match the seismogram to a chart called the Richter Scale

Invented in 1935

The scale is from one to ten, with any earthquake above 6 being very destructive

Formation High temperature High Pressure Liquid State Found in pockets called magma chambers Magma constantly moves and works its way through cracks toward the surface by melting the solid rock Volcanoes Magma: Rock deep within the Earth

Formation

High temperature

High Pressure

Liquid State

Found in pockets called magma chambers

Magma constantly moves and works its way through cracks toward the surface by melting the solid rock

Magma: Rock deep within the Earth

Formation Lava – Magma that has reached the Earth’s Surface The place where magma becomes lava is called a Volcano The opening through which lava erupts is called a vent Volcanoes can have more than one vent Lava will poor from the sides of a volcano as well as the top Volcanoes

Formation

Lava – Magma that has reached the Earth’s Surface

The place where magma becomes lava is called a Volcano

The opening through which lava erupts is called a vent

Volcanoes can have more than one vent

Lava will poor from the sides of a volcano as well as the top

All are not Alike Some are quiet Lava oozes from a vent Others are violent With lava and other material hurled hundreds of feet in the air Gases and earth material mix to be seen from miles away The opening through which lava erupts is called a vent Volcanoes can have more than one vent Lava will poor from the sides of a volcano as well as the top Eruption Eruptions

All are not Alike

Some are quiet

Lava oozes from a vent

Others are violent

With lava and other material hurled hundreds of feet in the air

Gases and earth material mix to be seen from miles away

The opening through which lava erupts is called a vent

Volcanoes can have more than one vent

Lava will poor from the sides of a volcano as well as the top

Eruption

Scientists study the makeup of the lava that spews from the Volcanoes vents to gain knowledge about the interior magma Types of Lava Dark-colored/ Water Light-colored/ little Water Chemical composition of both Large amounts of gases Steam and carbon dioxide Eruptions

Scientists study the makeup of the lava that spews from the Volcanoes vents to gain knowledge about the interior magma

Types of Lava

Dark-colored/ Water

Light-colored/ little Water

Chemical composition of both

Large amounts of gases

Steam and carbon dioxide

Eruptions During eruptions many rock fragments are blown into the air Smallest = volcanic dust Medium = volcanic ash Large = volcanic bombs Small volcanic bombs the size of golf balls are called Cinders

During eruptions many rock fragments are blown into the air

Smallest = volcanic dust

Medium = volcanic ash

Large = volcanic bombs

Small volcanic bombs the size of golf balls are called Cinders

Types of Volcanoes Different types of volcanic eruptions form different types of volcanoes Cinder Cones - made mostly of cinders and other rock particles that have been blown into the air Form from explosive eruptions Cones are not high Narrow base & steep sides Shield Volcanoes – composed of mostly quiet lava flows Gently sloping, domed shaped mountain forms Composite Volcanoes – Built up of alternating layers of rock particles and lava First is a violent eruption Then a quiet eruption After many alternating eruptions a cone shape is formed

Different types of volcanic eruptions form different types of volcanoes

Cinder Cones - made mostly of cinders and other rock particles that have been blown into the air

Form from explosive eruptions

Cones are not high

Narrow base & steep sides

Shield Volcanoes – composed of mostly quiet lava flows

Gently sloping, domed shaped mountain forms

Composite Volcanoes – Built up of alternating layers of rock particles and lava

First is a violent eruption

Then a quiet eruption

After many alternating eruptions a cone shape is formed

Types of Volcanoes At the top of a funnel-shaped pit or depression is a pit Called Crater If it becomes to large it is called a Caldera Super Eruption Discovery Channel :: Virtual Super volcano

At the top of a funnel-shaped pit or depression is a pit

Called Crater

If it becomes to large it is called a Caldera

Super Eruption

Discovery Channel :: Virtual Super volcano

Three Major Zones Nearly all the way around the edge of the Pacific Ocean Called the Ring of Fire Near the Mediterranean Sea Called the Mediterranean Zone Third Extends through Iceland to the middle of the Atlantic Ocean Mid-Atlantic Ridge – Long ridge of volcanoes Zones

Three Major Zones

Nearly all the way around the edge of the Pacific Ocean

Called the Ring of Fire

Near the Mediterranean Sea

Called the Mediterranean Zone

Third Extends through Iceland to the middle of the Atlantic Ocean

Mid-Atlantic Ridge – Long ridge of volcanoes