Post on 15-Jul-2015
GEOTECHNICS & APPLIED GEOLGIY
SUBJECT CODE: 2130606
EARTHQUAKES
B.E. 3RD SEM
Branch:-Civil
Div:-C
1HJD Institute of Technical Education and Research, Kera-Kutch.
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
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.
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.
Crust
Its Cool
What we live on
Composed of rocks,
various materials make
up the crust
Solid or Liquid?
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
Seismographs
record
earthquake
events
At convergent
boundaries, focal
depth increases
along a dipping
seismic zone
called a Benioff
zone
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.
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
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
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
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
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.
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.