Earthquakes - Earthquakes 1. Where do earthquakes occur? 1....

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Earthquakes 1. Where do earthquakes occur? 1. Mostly around convergent plate boundaries 1. Grenville (S. Ontario) – faults in this region are somewhat active and cause minor earthquakes 2. Most earthquakes (3 plates) coast of B.C. 3. After affects can be worse than earthquakes itself (ex. Tsunami caused by earthquake) Waves 1. Period – the time between seismic waves 2. Wavelength – the length from crest to crest of a wave 3. Frequency – the number peaks per second Seismograph 1. Tool to measure and record earthquake waves 2. Old fashioned seismographs also used today 3. Body waves occur FIRST 4. After S wave – when energy hits earth’s surface 5. Types of Seismograph: 1. Short-period seismographs : record local earthquakes (high freq) 2. Long-period seismographs : record distant earthquake (low freq) 3. Broadband seismographs : record both local and distant earthquakes; but cannot accurately measure strong earthquakes in the direct vicinity 4. Strong-motion Seismographs: record local and very strong earthquakes Earthquake Wave Types 1. Body Waves (go through earth’s surface) 1. P waves (primary or compressional): wave shakes back and forth along the direction of wave travel 1. 8 km/s upper mantle
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2. 5-6 km/s continental crust 1. S waves (secondary or shear): shakes back and forth perpendicular to the direction of wave travel (cannot travel through a liquid) 1. 4.5 km/s upper mantle 2. 3.5 km/s crust 1. Surface Waves (slower) 1. 2 – 4.5 km/s 2. Love Waves : move side to side 3. Rayleigh Waves : move up and down Basic Fault Types 1. Normal Fault 1. Lower wall will fall relative to upper wall 1. Reverse Fault 1. Lower wall will rise relative to upper wall 1. Thrust Fault 1. Move over each other 1. Strike-Slip Fault 1. Back and forth (slipping
Background image of page 2
Elastic Rebound Theory 1. The theory applied to most earthquakes in which movement on two sides of a fault leads to bending of the rocks until they slip and snap to release the bending strain 2. Stress: the force on a body
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

Earthquakes - Earthquakes 1. Where do earthquakes occur? 1....

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online