VOLCANOES Chapter 13 Part 2

IV. Types of Volcanoes e.g. Hawaiian Islands are examples of Shield Volcanoes A. Shield Volcanoes 1. Eruption: Non-explosive 2. Formation: repeated lava flows  wide and short

IV. Types of Volcanoes B. Cinder Cone Volcanoes 1. Eruption: Explosive 2. Formation: pyroclastic materials not cemented together  angle ( ∠ ) of repose = 30-40° ∠ that is the steepest ejecta can pile up w/out sliding downhill  narrow but tall

IV. Types of Volcanoes C. Composite Volcanoes (Stratovolcano) 1. Eruption: Alternating Explosive w/ Non-Explosive 2. Formation: alternating lava flows w/pyroclastic materials

IV. Types of Volcanoes C. Composite Volcanoes (Stratovolcano) 3. Dangers: a) Nuee ardente (aka glowing avalanche) = ash + steam 125 mph downhill b) Lahars = volcanic debri + water flow (due to melting snow or rainfall)  mix  flow tremendous speed

IV. Types of Volcanoes D. Calderas A. Magma chamber empties  overlying rock loses support  collapses  looks like a bowl sitting on earth B. Often fills with H 2 O e.g. Crater Lake, OR C. Can repeat process e.g. Crater Lake now has a small composite volcano in its center

V. Effects of Volcanoes on Earth  Destruction of property  Alteration of climate, even in remote areas  Coats leaves of plants  Clogs waterways  Buries vegetation  Lahars  Great extinction of life due to cooler climate

VI. Predicting Volcanic Eruptions Geothermal image of lava flows at Kilauea Volcano, Hawaii A. Earthquake activity a) Seismographs detect shifting of magma B. Temperature Changes a) Geothermal imaging of satellites detect magma rising to surface

VI. Predicting Volcanic Eruptions C. Surface Bulges a) Tilt meters detect pressure increases caused by magma rising to surface D. Measuring output of volcanic gases