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CHAPTER 5 - TOPIC 5 – EARTHQUAKES Name: __________________ 1. Seismologists study earthquakes by reading seismographs. The report that is printed out is called a seismogram. A seismometer is a special machine scientists use to measure earthquakes magnitude and are attached to bedrock. Please describe how it works. A machine attached to bedrock (where it is sturdy and stable). When an earthquake happens, a pen attached to a lever moves. The pen records the results on a rotating drum. The larger the line, the greater the earthquake. 2. What is a Richter scale? p.396 A scale used to describe the magnitude of an earthquake. Each time we go up 1.0 on the Richter scale, the strength of the earthquake increases about 30 times. 3. Define seismic waves – energy waves that travel outwards from the source of the earthquake (the FOCUS) aftershock – smaller ground movements that come after the first earthquake 4. Types of E-Quake Waves Type of WAVE Key Info (time/travel thru/damage?) 1. Primary Waves (P – Waves) - 2. Secondary Waves (S – Waves) - faster than surface but slower than primary - can pass only through solids - medium amount of damage 3. Surface Waves - fastest waves weakest pass through all solid/liquid/gas least amount of damage slowest waves strongest pass through only solids most amount of damage 5. Why is it important to know that some waves go through liquid and others do not? - We need to consider these aspects when designing buildings and deciding where to build 6. It is possible to determine the location of an earthquake by the intervals between P and Secondary waves. The further apart they are the farther away the earthquakes. p.399 7. Please copy the diagram on p. 399 and define focus – where the earthquake begins inside the earth epicenter – where the earthquake originates on the surface of the earth. Directly above the focus. 8. Rock Mov’t in E-qukes p. 403 The rock in the Earth’s crust is under pressure from tremendous forces causing rock to bend or stretch. If the pressure is too great, the rock break suddenly, creating a fault. 9. Please sketch and briefly describe the three types of faults on p. 403? Fault Normal Fault Reverse Fault Strike-Slip or Transform Fault Tension Compression Shear DIAGRAM FORCES What occurs? Plates stretch apart and The rock is squeezed break, valleys will by the movement of form the plates, forcing them up and over other rocks The rocks have many bumps and bulges on them. They become twisted and strained and eventually break 10. Why does a rigid structure break during earthquakes? p. 404 They have very little flexibility/give within the joints of the structure. 11. What is a Tsunamis? p. 405 (liquefaction) A large wave the has been created by an earthquake in the ocean or the sea (Ex. Japan)