This document provides information about earthquakes. It discusses what causes earthquakes, including the sudden release of energy and faulting or breaking of rocks. The elastic rebound theory is explained, where rocks bend until failure causes a rupture and release of energy in seismic waves. Earthquakes typically occur at plate boundaries, with 80% in the circum-Pacific belt and 15% in the Mediterranean-Asiatic belt. Various types of seismic waves transmit energy from quakes. Surface waves especially can damage buildings. Factors like duration of shaking, soil conditions, and building quality influence earthquake damage.

1. Topic Name: EARTHQUAKES
Gandhinagar Institute
OF Technology
Presented By: Guided By:
Prof. SANDESH SHARMA
RAHUL PANCHAL(40)
KISHAN PANCHAL(37)
HIREN PANCHAL(36)
DHRUVIL PANCHAL(34)

2. What are Earthquakes?
• The shaking or trembling caused by the sudden
release of energy
• Usually associated with faulting or breaking of rocks
• Continuing adjustment of position results in
aftershocks

3. What is the Elastic Rebound Theory?
• Explains how energy is
stored in rocks
– Rocks bend until the
strength of the rock
is exceeded
– Rupture occurs and
the rocks quickly
rebound to an
undeformed shape
– Energy is released in
waves that radiate
outward from the
fault

4. The Focus and Epicenter of an Earthquake
• The point within Earth
where faulting begins is
the focus, or hypocenter
• The point directly above
the focus on the surface
is the epicenter

5. Where Do Earthquakes Occur and How Often?
~80% of all earthquakes occur in the circum-Pacific belt
– most of these result from convergent margin activity
– ~15% occur in the Mediterranean-Asiatic belt
– remaining 5% occur in the interiors of plates and on
spreading ridge centers
– more than 150,000 quakes strong enough to be felt are
recorded each year

6. FOR EARTHQUAKES
DETAILS VIDEO

7. The Economics and Societal Impacts of EQs
Damage in Oakland, CA,
1989• Building collapse
• Fire
• Tsunami
• Ground failure

8. EARTHQUAKE IN NEPAL

9. What are Seismic Waves?
• Response of material to the
arrival of energy fronts released
by rupture
• Two types:
– Body waves
• P and S
– Surface waves
• R and L

10. Body Waves: P and S waves
• Body waves
– P or primary waves
• fastest waves
• travel through solids,
liquids, or gases
• compressional wave,
material movement is
in the same direction
as wave movement
– S or secondary waves
• slower than P waves
• travel through solids
only
• shear waves - move
material
perpendicular to
wave movement

11. Surface Waves: R and L waves
• Surface Waves
– Travel just below or along the ground’s surface
– Slower than body waves; rolling and side-to-side
movement
– Especially damaging to buildings

12. • Ground motion
• Duration of Shaking
• Surface Rupture
• Poor building design
Damage: Causes

13. • Rupture
• Death
• Bldg collapse
Effects

14. Effects
• Fires
• Liquifaction
• Landslides

15. Damage:
Key Factors
• Amount & duration of shaking
• Water content of soil
• Population concentration
• Building construction
• Distance from Epicenter
• Depth of focus
• Direction of rupture
• Material amplification

16. EARTHQUAKE CLASSIFICATIONEARTHQUAKE CLASSIFICATION
MAGNITUDE CLASSIFICATION
M ≥ 8.0 Great Earthquake
7.0 ≥ M < 8.0 Major / Large Earthquake
5.0 ≥ M < 7.0 Moderate Earthquake
3.0 ≥ M < 5.0 Small Earthquake
1.0 ≥ M < 3.0 Microearthquake
M < 1.0 Ultra Microearthquake

17. NATURE OF EARTHQUAKESNATURE OF EARTHQUAKES
1) Foreshocks
2) Main shock
3) Aftershocks
4) Earthquake Swarm
5) Normal Seismic activity

18. CLASSIFICATION DISTANCE
1) Teleseismic Earthquake > 1000 km
2) Regional Earthquake > 500 km
3) Local Earthquake < 500 km
TYPES OF EARTHQUAKESTYPES OF EARTHQUAKES
1) Tectonic Earthquake
2) Volcanic Earthquake
3) Collapse Earthquake
4) Explosion Earthquake