1) Earthquakes are caused by vibrations induced in the earth's crust due to internal or external forces that shake parts of the crust and structures on it. 2) Seismographs are instruments used to measure earthquake vibrations and locate the focus or epicenter. The focus is the point where faulting begins inside the earth, and the epicenter is the point directly above the focus on the surface. 3) There are two main types of seismic waves produced by earthquakes: body waves that travel through the earth's interior, and surface waves that travel along the surface.

1. GEOTECHNICS & APPLIED GEOLGIY
SUBJECT CODE: 2130606
EARTHQUAKES
B.E. 3RD SEM
Branch:-Civil
Div:-C
1
HJD Institute of Technical Education and Research, Kera-Kutch.

2. Presented By:
ROLL NO.: NAME ENL. NO.:
57 PRAJAPATI JITENDRA P. 130850106062
31 JIVANI KULDEEP 130850106032
52 PATEL SAVAN . 130850106057
53 PATEL TEJAS. 130850106058
21 GOSWAMI DENISH 130850106022
58 PRAJAPATI PUNIT B. 130850106063

3. What are Earthquakes
 Vibrations induced in the earth’s
crust due to internal or external
causes that virtually shake up the a
part of the crust and all the
structures along with living and non-living
things.

4. Interior of earth

5. INNER CORE
 Thought to be as hot as
the surface of the Sun!
– Solid
– Composed of Iron and
Nickel

6. Outer Core
 Hot
(but not as hot as the inner core)
– Liquid
– Composed of Iron and Nickel

7. Mantle
 Still hot! –
(but not as hot as the core!)
– Largest layer
– Composed of various materials
– Solid and liquid
– Made up of ultra basic rocks.

8. Crust
 Its Cool
 What we live on
 Composed of rocks,
various materials make
up the crust
 Solid or Liquid?

9. 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

10. Seismographs
record
earthquake
events
At convergent
boundaries, focal
depth increases
along a dipping
seismic zone
called a Benioff
zone

11. Seismographs
 A seismographs is an instruments
used to measure the vibration of the
earth.

12. COMPONENSTS
 The sensor :- consisting of the pendulum mass,
string, magnet and support.
 The recorder :- consisting of the drum, pen and
chart paper.
 The timer :- consisting of the motor that rotates
the drum at constant speed.

13. 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

14. 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

15. 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

16. Causes of earthquakes
 Two main causes of earthquakes
– Tectonic earthquakes
• Stressing
• Straining ( Flexuring & fracturing)
Elastic Rebound theory
• Faulting
– Reservoir induced earthquakes
• These are caused due to
– Sagging effect
– Increased pore pressure
– Man made cause like atomic explosion,
blasting activity in mining,
– Volcanic explosions

17. Effects of earthquakes
 The earthquakes are classified into two
– Primary effects
– Secondary effects
 Primary effects
– It includes effects which are directly related to the cause of
origin of an earthquake. Tectonic activity is often responsible
for producing major changes in the geological structures of an
area like;
• Creation of slope
• Fissures, streams
• Origin of new springs and sand dike
• Emergence or subsidence of coastlines.

18.  Secondary effects:
– These are related to the passage of
seismic waves associated shaking
motion of ground.
• Landslides
• Collapse of building, bridges, dams, poles.
• Huge waves arising in sea water called as
tsunamis.
• Mental misbalancing; fear,panic.