Earthquakes & Volcanoes

Earthquakes & Volcanoes

Photos should be credited as "Robert A. Eplett/OES CA"California Governor's Office of Emergency Services

Earthquakes • A. When rocks break they move along __________. • 1. Applied forces cause rocks to undergo __________________. • When elastic _________ are passed, rocks break. • Rock on one side of a fault can move _______, ___________, or _________ in relation to rock on the other side of the fault. faults elastic deformation limits up down sideways

Earthquakes (continued) • B. Faults occur because forces inside Earth cause Earth’s __________ to move placing stress on or near the plate edge. • 1. Rocks will bend, compress, ___________, and possibly break. • ___________ - vibrations produced by breaking rock. • a. Rocks break, move along the fault, return to original ________. plates stretch Earthquake shapes

Earthquakes (continued) • B. (continued) • (continued) • b. Rock on one side of a fault can move over, under, or ________ each other along fault lines. past

C . Three types of __________ • act on rocks – tension, • compression, and shear. • 1. Tension forces; _________ fault – caused by rock above the fault moving downward in relation to the rock below the fault. • 2. __________ fault – compression forces squeeze rock above the fault up and over the rock below the fault. forces normal Reverse

C . (continued) • 3. Created by shear forces; ___________ fault – rocks on either side of the fault move past each other without much upward or downward motion. strike-slip

II. Volcanoes • Volcano – opening in Earth that erupts gases, ash, and __________. • Volcanoes can kill people, destroy property, and disrupt the _______________. • 1. Lava and ___________ flows can bury cities and towns in their paths. lava environment pyroclastic

II. Volcanoes (continued) • B. (Continued) • 2. Sulfurous gases from volcanoes can create ___________, which can kill organisms and pollute water. • C. Volcanoes form when magma flows out of a surface opening called a __________; a steep-walled depression around the vent is called a ____________. acid rain vent crater

II. Volcanoes (continued) • D. Volcanoes often form where __________ are moving together or moving apart. • 1. The Mid-Atlantic Ridge is a ____________ plate boundary that forms rifts through which lava can flow. • 2. At ____________ plate boundaries, volcanoes tend to erupt more violently than they do in other areas. plates divergent convergent

II. Volcanoes (continued) • D. (continued) • 3. At the boundary between Earth’s mantle and core, unusually hot areas form _______________, such as at the Hawaiian islands. hot spots

II. Volcanoes (continued) • E. Three types of volcanoes form from the three types of ________. • 1. As quiet eruptions of basaltic lava spread out in flat layers, they form a broad volcano with gently sloping sides called a _________ volcano. • 2. As tephra (bits of rocks or solidified lava) falls to the ground, it forms a steep-sided, loosely packed ____________ volcano. lava shield cinder cone

II. Volcanoes (continued) • E. (continued) • 3. A __________ volcano forms from alternating layers of quiet lava and more explosive tephra. composite

Earthquakes & Volcanoes