Seismic WavesMuhammad Kamran

Kamran.be12@igis.nust.edu.pk

What are seismic waves?

Full of energy

Very fast moving (Speed in km/s)

Breaking of rocks

EarthquakeSeismic Waves

History

• Chinese attempted 2000 years ago to

determine support attached to the ground.

• Ancient people superstitions.

• Seismology: The study of seismic waves is

called as seismology.

• and it is YOUNG SCIENCE >> 150 years

approx.

Some terminologies

• Focus: The location within the earth

where rocks damage take place is called

focus of the earthquake. Seismic waves

first originate here.

• Epicenter: The point on surface of earth

right above the focus is known as

epicenter.

Types of Seismic Waves

P-waves

S-Waves

Love and Rayleigh waves

Earthquake - Epicenter Location:

Earthquake – Depth of Focus:

Category Depth kms

Shallow focus 0-70

Intermediate 70-350

Deep 350-670

Estimated by doing analysis on seismogram,

It is calculated by different in velocity of p and s

waves and arrival at recording station.

Measuring size of Earthquake

• Modified Mercalli scale:

• Richter scale:

Effect of Seismic Waves (Earthquakes):

• Vibration and damage of buildings.

• Life losses and injuries due to hitting of falling debris

from buildings during earthquake.

• Liquefaction which is flowing of water saturated soil after

getting shake due to earthquake.

• Probability of fire after earthquake due to broken gas

pipes and electric lines.

• Landslides triggered by shaking of ground.

• Tsunamis i.e. high rising water waves due to disturbing

of water equilibrium in case of shaking.

Th

e E

nd

!