Earth’s Structure, Earthquakes and Volcanoes Review

What does the surface of the Earth look like? The outermost layer of the earth is called the crust. · The mantle is the layer of the earth that lies just beneath the crust, it is the thickest. · The crust and the top of the mantle form the lithosphere. · The lithosphere is broken into many large pieces of earth, or lithospheric plates, that are always moving. · Lithospheric plates = Tectonic plates

Layers of the Earth Crust, Mantle, Outer core, Inner core The Earth’s inner core is mad up of dense, solid metal. The Earth’s lithosphere is the part of the earth that contains plates. The Mantle is the thickest of the Earth’s layers.

Earthquakes - Seismic Waves Seismic waves known as S and P waves P Waves are known as Primary waves S Waves are known as Secondary Waves Both waves leave at the same time, but P waves arrive first.

P Waves Primary Push and pull Compressional waves Travels fast Wave travels parallel to the direction of the wave Can travel through water

S Waves Known as secondary waves side to side transverse waves travels slow wave travels perpendicular to the direction of the wave Cannot travel through water

Rating System Richter Scale – measures total energy released Mercalli Scale - measures damage

Epicenter and Focus The point beneath the earth’s surface where rock breaks and triggers an earthquake is called the FOCUS. The point on the Earth’s surface that is directly above the focus is called the EPICENTER.

Force causes Stress Stress occurs when force acts on rock to change its shape or volume.

Body and Surface Waves Body Waves – Occur inside the earth and are known as Primary and Secondary waves (S and P) Surface Waves - Occur on the surface. Two types - Love and Rayleigh

Aftershock An aftershock can cause damage weeks or months after a large earthquake

Volcanoes Most volcanoes are found along mid-ocean ridges and where a plate is subducted. Oceanic to Oceanic and Oceanic to Continental

Detection When geologists detect many small earthquakes in the area near a volcano, the volcano is most likely about to erupt.

Magma and Lava Magma is molten material inside the volcano. Lava is molten material found outside the volcano.

Types of Volcanoes

Volcano Formation Cinder Volcano – are formed by lava fragments called cinders are blown from a single vent and accumulate around the volcano. Composite Volcano – are formed by alternating layers of lava and rock fragments. This is the reason they are called composite. Shield Volcano – are built by many layers of runny lava flows. Lava spills out of a central vent or group of vents. A broad shaped, gently sloping cone is formed.

Plate Boundaries Diverging Plate Boundaries – Plates that move or pull apart from one another. HINT: divide Converging Plate Boundaries – Plates that collide such as oceanic to oceanic or oceanic to continental. Where the heavier or more dense plates slides under the other plate. HINT: Come together

Additional Info Caldera is a huge hole left by the collapse of a volcanic mountain. Volcanic ash is made up of fine, rocky particles as small as a speck of dust, but can be very hazardous. Lava Flows are the main hazard from a quiet volcanic eruption.

Earth’s Interior Oceanic Crust – The outermost layer of Earth’s lithosphere that is found under the ocean. The oceanic crust is made of Basalt.lithosphere Continental Crust – The outermost layer of the Earth’s surface found on land. The continental crust is thicker and made up of granite. Lithosphere – The layer of the earth that is made up of part crust and part mantle.

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