Earthquakes and volcanoes

Ex. San Andreas Fault in California EARTHQUAKES happen along fault lines which are on transform boundaries but can happen on divergent and convergent boundaries as well shake the Earth Ex. San Andreas Fault in California

Focus – exact point INSIDE the Earth where earthquake originated Epicenter – point on Earth’s SURFACE directly above the focus

3 TYPES OF EARTHQUAKE WAVES 1. Primary/Push Waves (P waves) longitudinal move fast in all directions not much damage (because they are so quick moving)

2. Secondary/Shear Waves (S waves) transverse move slower than P waves & in all directions more damage than P waves

3. Surface/Love Waves (L waves) make Earth shake and vibrate most destructive because they are slow and rolling waves collapses buildings

One thing to note: S waves cannot travel through solids so they will never go through Earth’s core, only the liquid mantle. P waves can travel through both solids and liquids.

Earthquake Terms Seismology – the study of earthquakes Seismographs – instrument used to record earthquake waves Richter Scale – scale used to measure earthquake strength/intensity

VOLCANOES They are openings in the Earth’s crust through which magma escapes These openings are called VENTS Formed by subduction (one plate goes under another), rifting (plates pull apart) & hotspots (spot in middle of plate)

3 Types of Volcanoes 1. Shield Volcano -flat, not steep -lava flows great distances b/c it is runny -eruptions are mild -Ex. Hawaiian Islands

2. Composite (Strata) Volcano -made of layer of ash, cinder, lava -puffy clouds of ash -trapped gases cause explosions that go thousands of meters in the air -Ex. Mt. Fuji, Japan

3. Cinder Cone Volcano -smaller, most abundant -trapped gases throw ash particles everywhere which forms the “cone” -Ex. Paricutin, Mexico

Volcanoes occur at divergent and convergent boundaries Pacific Ring of Fire 

Volcanoes that occur under water are called SEAMOUNTS