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.

Interior of earth

INNER CORE

Thought to be as hot as

the surface of the Sun!

– Solid

– Composed of Iron and

Nickel

Outer Core

Hot

(but not as hot as the inner core)

– Liquid

– Composed of Iron and Nickel

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

Seismographs

A seismographs is an instruments

used to measure the vibration of the

earth.

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.