Download presentation
Presentation is loading. Please wait.
1
Earthquakes Movement & Destruction
2
What is an Earthquake? Shaking of the Earth produced by a sudden movement of rock beneath its surface
3
How Do Earthquakes Occur? Elastic Rebound Theory Deformation builds up and causes crust to bend When strain exceeds strength of the rock, it will “snap” into a new position In the process of rupturing, energy is released in the form of “seismic waves” Elastic strain energy is stored
4
Where Do EQ Occur? Faults – Fracture in the Earth’s crust where one side moves with respect to another
5
Types of Fault
6
Fault Terminology – Fault block above the fault – Fault block below the fault Footwall Hanging wall
7
Normal Fault Hanging wall moves down relative to the footwall Exhibits lengthening or extension of the crust Associated with fault block mountains – Basin and Range – Horst – uplifted block – Graben – down dropped block
8
Basin and Range
9
Reverse Fault Hanging wall moves up relative to footwall Exhibits shortening or compression of crust Have dips > 45° If dip’s < 45°, then thrust fault
10
Strike-Slip Fault Horizontal displacement – Right lateral – As you face the fault, opposite side of plate moves right Types of Strike Slip: – Left lateral – opposite side of plate moves left
11
San Andreas Fault
12
Destruction from EQ Ground Shaking Tsunami Fire Liquefaction
13
Destruction from EQ Ground Shaking Rapid horizontal movement of ground may shift homes and cause them to collapse Shaking is exaggerated in water-saturated or weak sediment
14
Northridge, CA – 1994 M=6.7; 61 killed
15
Destruction from EQ Tsunami Giant Sea Waves generated by submarine EQ’s Tsunamis travel 1,000’s of miles Waves may reach 15 m (50 feet) in height and travel up to 960 km/hr (600 mph)
16
Alaska - 1964 M = 9.2; 125 died (110 tsunami, 15 EQ)
17
Alaska, 1964 There was so much uplift that once-submerged areas were exposed after EQ
18
Indonesia 2004 M=9.0; 280,000 killed
19
Destruction from EQ’s Fires Many gas lines may break from the severe shaking Unfortunately, many water lines may break as well so that firefighting becomes impossible
20
San Francisco - 1906 M = 7.8; 3,000 killed
21
Destruction from EQ’s Landslides Mountains usually form in areas of convergent boundaries The steep slope are prone to landsides when shaken Landslides are common following EQ’s in California
22
Northridge - 1994 Landslides prevalent in Santa Susana Mountains
23
Destruction from EQ’s Liquefaction Occurs when water-saturated is reorganized due to violent shaking Sediment collapses, expelling water, and causes the ground to subside
24
U.S. Earthquake Hazards
25
San Andreas Fault
26
Southern California Seismicity
27
Southern California Faults
28
Earthquake Predictions
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.