文档介绍：普通地质学英文课件
Lecture_10 Earthquakes
Lecture_12 Landslides
Lecture_13 Floods
Lecture_14 Cumulative Impact in Canada
Lecture_15 Water
Lecture_16 Water Pollution
Lecture_17 Energy Resources
Lecture_18 Impacts of Mineral Extraction and Processing
Earthquakes
What is an earthquake?
An event that releases stored energy in the earth’s crust
Takes place along a fault plane
Can be naturally-occurring or human-induced (. explosives used in mining)
Large enough earthquakes manifest themselves on the surface of the earth through shaking and other ground displacement
Earthquake Distribution
USGS – earthquakes magnitude or greater (major convergent boundaries circled)
What causes earthquakes?
As we know, the Earth’s lithosphere is divided into plates that interact with each other
Any gradual build up of stress due to the movement of plates can eventually be released as energy when the rocks that are stressed finally break
Elastic Rebound Theory
Describes the sudden release of the accumulation of stress causing movement along a fault
New fault or existing fault
Requires that rock is somewhat ductile
It can bend without breaking
Remember stress vs. strain (Lecture 3)
The deeper the rock in question, the more ductile it is
warmer
Rock that is deep enough to undergo plastic deformation will not generate earthquakes
Types of Faults(Review from Lecture 3)
There are three main categories of faults
Normal fault
Reverse fault
Thrust fault is a type of reverse fault
Strike-slip fault
Transform fault is a type of strike-slip fault
Normal Fault
Not mon, despite the name
One land mass moves away from another with gravity
Forms fault scarps
Fault scarp
Reverse Fault
Occurs where one land mass is pushed upwards against another land mass
If the angle of contact is less than 45°, it is called a thrust fault
Strike-slip Fault
Occurs at transform margins
One land mass slides past another one with negligible vertical motion