concepts and technical terms

2. Introduction
• Earthquake is a natural disaster, occurs due to sudden
shaking of ground caused by passage of seismic
waves through earth rocks, which results movements
tectonic plates.
• It is associated with faulting or breaking of rocks.
• Seismic waves produced when some form of energy
stored in earth crust is suddenly released.
• Most earthquake occur along the edge of the oceanic
and continental plate.
Definitions:
• Earthquake-vibration of earth produced by rapid
release of energy.
• Seismic waves-Energy moving outward from the focus
of an earthquake

3. •Earth Interior

4. Technical terms
• Lithosphere
• Focus
• Epicenter
• Seismic waves
• Seismometer
• Seismograph
• Seismogram
• Magnitude : Richter Scale
• Intensity : Mercalli’s Scale
• Fault : Strike-slip

5. • Focus-The point within earth surface where faulting begins is the focus or hypocenter.
• Epicenter-The point directly above the focus on the surface is the epicenter.
• Fault -A planar or curved fracture in the rocks of the earth crust, where compressional or
tensional forces cause relative displacement of the rocks on opposite sides of the fracture.

6. Seismic Waves
• Seismic waves are energy waves that move through
the earth.
• It is useful to study the structure of the earth by
monitoring how the wave pass to the interior of the
earth.
Types
Body Waves
Travel through the interior earth and
move faster than surface waves.
 P-Wave-primary or compression wave
 S-Wave-transverse or shear wave
Surface Waves
 Long Wave
 Rayleigh Wave

8. Measuring Instrument
• Seismometer-Detects seismic waves
• Seismograph-Records intensity, Height and
amplitude of seismic waves.
• Seismogram-Graphical output of seismograph.
Measurements
Magnitude-measured value of the earthquake
size.
• one per earthquake
• Related to energy released
• Richter or moment scale
Intensity-Measure of shaking created by the
earthquake, values vary with locations.
• Many for each earthquake
• Measures of effects
• Mercalli Scale

9. Classification of Earthquake Measurements

10. Causes of Earthquake
• Volcanic activities
• Folding and faulting
• Plate tectonics movements
• Human interface with nature( Mining, Drilling, Explosives etc..)
Largest Earthquake(world): Instrumentally documented in southern Chile on
may22,1960 at the magnitude of 9.5.Referred as “The Great Chilean
earthquake”.
Important places for earthquake around world:
• 90% of world earthquake occurs in “Ring of fire”.
• Next most seismic region-Mediterranean region(5-6%)
• Estimation: Each year 5,00,000 are detectable.100 of them cause damage.

11. IN INDIA
Gujarat : Bhuj Earthquake(Epicenter)
7.7 Richter scale, Jan 2001,(2 minutes)
Time:8.40 AM
Maharashtra : Kilari in Latur district(Epicenter)
6.2 ,Sep 1993.
Time:3.56AM,Depth:10km
Bihar : Near Eastern Nepal(Epicenter)
8.0 ,Jan 15,1934.
Time:2.28PM,Depth:15Km
Uttarkashi : Uttarkashi and Bash Wari region(Epicenter)
6.1,Oct 20,1991
Time:2.53AM,Depth:11.6Km

12. Death
Ground motion Poor Construction of building Landslide
Rupture Fire
Effects

13. • Earthquake
zones of India

14. REFERENCE
• https://earthquake.usgs.gov/learn/facts.php
• https://www.quora.com/What-causes-earthquakes
• https://www.britannica.com/science/earthquake-geology
• https://www.conserve-energy-future.com/howearthquakesoccur.php
• http://paleoseismicity.org/things-that-cause-earthquakes/
• https://www.srmbsteel.com/content/4-disastrous-earthquakes-shook-india
• http://asc-india.org/seismi/seis-tamil-nadu.htm
• http://asc-india.org/seismi/seis-tamil-nadu.htm
• https://www.iris.edu/hq/files/programs/education_and_outreach/aotm/8/Seismogr
aph_Background.pdf