Do First Actions Turn in Volcano vs Earthquake

Do First Actions: Turn in Volcano vs Earthquake Webquest Questions: 1. What type of plate interaction(s) forms volcanos? 2. What type of plate interaction(s) does not form volcanos? Boys rules still apply, hop up and get 30 minutes with me

Agenda • Test is Wednesday: Plate Tectonics, Earthquakes, and Volcanos • Volcano Notes • Volcano Video

Pixar Video https: //www. youtube. com/watch? v=uh 4 d. TLJ 9 q 9 o

What is a volcano? • A volcano is a rupture on the crust that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface

Where do Volcanos occur? • Volcanos mostly occur at convergent and divergent plate boundaries • Plate motion causes mantle rocks to melt to form magma

What causes volcanoes?

Where do Volcanos occur? • Convergent boundaries produce volcanic arcs • At Ocean – ocean convergent boundaries rising magma can form volcanic arcs in an ocean (Aleutian Islands). • At Ocean – continental boundaries rising magma can form continental volcanic arcs (Andes Mountains). • 75% of volcanos occur in the “Ring of Fire” • Divergent boundaries produce the greatest volume of volcanic rock along the oceanic ridge system

Where do Volcanos occur? • The remaining volcanos occur within a plate and not at a boundary which is called intraplate volcanism • The regions are known as “hot spots” • Volcanos occur here because a mass of hotter than normal mantle material called a mantle plume rises toward the surface. • The Pacific plate moves over a hot spot, producing the Hawaiian Islands.

Mantle Convection Models

Hot Spots

Types of Eruptions • Violent (Explosive) • Destroy the volcano • Viscous (thick) lava traps the gases until large pressures build up & the system explodes • Pyroclastic flow (ash, rock fragments) flow out of vent • Non-violent (Calm or Quiet) • Build up the volcano • Fluid lava flows easily allows gases to bubble away

Types of Lava • Lava is what magma is referred to once it reaches the surface • Viscous Lava (Thick) • Cool temperature • Composition: silica-rich (granitic) • Fluid Lava (Thin) • Higher temperatures • Composition: Low silica (basaltic)

Other Ejected Materials • Dissolved gases • Mainly water vapor and carbon dioxide • If gases escape easily then eruption is less explosive • Pyroclastic Materials • particles produced in volcanic eruptions • Range in size from very fine duct and volcanic ash (less than 2 millimeters) to pieces that weigh several tons

Pompeii After the 79 C. E. eruption

Parts of a Volcano • A volcano is a mountain formed of lava and/or pyroclastic material. • A crater is the depression at the summit of a volcano or that which is produced by a meteorite impact. • A conduit, or pipe, carries gas-rich magma to the surface.

Types of Volcanos Shield volcano Composite volcano Cinder cone volcano

Types of Volcanos • The three main volcanic types are shield volcanoes, cinder cones, and composite cones.

Types of Volcanos • Shield Volcanoes • Shield volcanoes are broad, gently sloping volcanoes built from fluid lavas.

Types of Volcanos • Cinder Cones • Cinder cones are small volcanoes built primarily of pyroclastic material ejected from a single vent • Steep slope angle • Rather small in size • Frequently occur in groups

Types of Volcanos • Composite Cones • Composite cones are volcanoes composed of both lava flows and pyroclastic material. • Large size • Alternating layers of lavas and pyroclastics • Most violent type of activity

Types of Volcanos • Volcanos can also be defined by when they are expected to erupt • Active: has erupted in the last 10, 000 years • Dormant: hasn’t erupted in the last 10, 000 years but it expected to erupt again • Extinct: hasn’t erupted in the last 10, 000 years and is not expected to erupt again

Mount St. Helens Before and After the May 18, 1980, Eruption https: //www. youtube. com/watch? v=UK--hvg. P 2 u. Y

DYL • 1. What are three types of volcanos? • 2. What is a hot spot?