Egrm
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EGRM Earthqauke study India Govt. College of Engg. Aurangabad M.S.
Transcript of Egrm
Presented By – Nikhil Kulkarni BE09F01F001Mudassir Shaikh BE09F01F003Pirpasha Ujede BE09F01F012Rahul Agrawal BE09F01F017
India is vulnerable to different natural hazards due to its proximity to geodynamically active locales and unique climatic pattern. Both these factors in different combinations lead to the occurrence of disasters resulting from naturalhazards like floods, earthquakes, draught, cyclones and landslides in different parts of the country at frequent intervals. It is estimated that about 60% of landmass of the country is vulnerable to earthquakes of different magnitudes.
Sikkim experienced a major destructive earthquake of 6.9 (Mw) heating badly causing deaths of no of people and d.At least 20 aftershocks at magnitudes of 5.7, 5.1, and 4.6 (Mw) within 30 minutes of the initial earthquake occurred back-to-back throughout the night created panic in the Gangtok.
Q:What is earthquake?
A:” When the edge of two pieces of the earth grind together and cause rumbling and shaking underneath the surface of the earth. The shaking or trembling caused by the sudden release of energy is earthquake. Usually it is associated with faulting or breaking of rocks”.
Q:What are the causes of earthquake?A:”The earth is divided into three main layers
– a hard outer crust, a soft middle crust, and a center core. The outer crust is broken into massive irregular pieces called “plates”. These plates are moving very slowly, driven by energy forces deep within the earth. Earthquakes occur when these moving plates grind and scrape against each other.”
What is the Elastic Rebound Theory?
Explains how energy is stored in rocks– Rocks bend until
the strength of the rock is exceeded
– Rupture occurs and the rocks quickly rebound to an undeformed shape
– Energy is released in waves that radiate outward from the fault
Causes of Earthquake Two Types aftershock and foreshock
” An aftershock is a small earthquake that follows the main earthquake.
A foreshock is a small earthquake that often precedes a major earthquake”.
Earth’s Layered Structure
INDO-AUSTRALIAN PLATE
Eurasian Plate
Map of Plate Tectonics
Tectonic map
ComPrensive
Focus, Epicenter, and FaultThe point within Earth’s interior where the energy waves are produced and where faulting begins is the focus, or hypocenter
The point on Earth’s surface directly above the earthquake focus is Epicenter
Fault is fracture in Earth where movement has occurred
Locating an EpicenterEpicenter Location
– If information is received from the earthquake at three stations, then the epicenter can be located
– A circle is drawn around each station on a map• The radius is equal to the distance from the station to the epicenter
– The point in which all three circles intersect is the earthquake epicenter
Types of Faults
” Strike-slip Fault– Earth’s plates move sideways to one
another– Creates a shear force– Rocks on either side of the fault surface
are moving past each other without much upward or downward movement”.
Q: Where are earthquakes most prone to occur?
A: ‘’There is no technology available in any part of the world to determine the place, time, or magnitude, of an earthquake. However, they are most likely to occur where the plates meet. They are most prone to the fault line of the plates. Because the plates are in constant motion.
Q:Where Do Earthquakes Occur and How Often?
A: 80% of all earthquakes occur in the circum-Pacific belt– most of these result from convergent
margin activity– ~15% occur in the Mediterranean-
Asiatic belt– remaining 5% occur in the interiors of
plates and on spreading ridge centers– more than 150,000 quakes strong
enough to be felt are recorded each year
•Record seismic waves•A drum with a sheet of paper vibrates and a stationary pen marks the vibrations on the paper•The height of the lines are used to measure the energy released from the earthquake called the magnitude•The magnitude of Sikkim Earthquake was 6.9 on Richter Scale
Seismograph
Seismograms
Seismograms are traces of amplified, electronically recorded ground motion made by seismographs
Q:What are Seismic Waves?A: 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
Sr.No. Date Time of aftershocks
Hr:Min (In IST)
Magnitude
1 18.09.2011 18 :42 5.3
2 18.09.2011 19:24 4.6
3 18.09.2011 20:35 3.0
4 19.09.2011 00:57 3.4
5 19.09.2011 03:21 3.8
Aftershocks
Seismicity of the world
•Past seismicity of the regionHistorical and instrumentally recorded data on earthquakes show that the Sikkim and adjoining area lies in a region prone to be affected by moderate to great earthquakes in the past. Some noteworthy earthquakes that have affected the region are:Cachar earthquake of 10.01.1869 (M: 7.5),Shillong plateau earthquake of 12.06.1897 (M: 8.7),Dhubri earthquake of 02.07.1930 (M: 7.1),Bihar-Nepal Border earthquake of 15.01.1934 (M: 8.3),Arunachal Pradesh – China Border earthquake of 15.08.1950 (M: 8.5),Nepal-India Border earthquake of 21.08.1988 (M: 6.4)Sikkim earthquake of 14.02.2006 (M: 5.7)Bhutan earthquake of 21.09.2009 (M:6.2)
Earthquake Magnitudes
Impact
Country Deaths Injured DisplacedDamaged Houses / Buildings
Partially Damaged Buildings
Total LossBillion US
Dollars
India 115 184 16500 15000 3,186 22.3
China 7 136 13790 156 2960 NA
Nepal 6 25 - 4360 2800 NA
Bhutan 1 16 - 6000 - NA
Bangladesh 0 - - - - NA
Total 129 - - - - -
Landslides are one of the natural hazards that affectat least 15% of land area of our country exceeding 0.49million km2. Landslides of different types occur frequentlyin geodynamically active domains in Himalaya,
Tremors
The strong tremor jolted buildings across northern and eastern India, including Delhi, Uttar Pradesh, Uttarakhand, Jharkhand, Bihar, West Bengal, Assam and Mizoram, prompting people to run out of their homes in panic.
Destruction from Earthquakes
LandslidesWith many earthquakes, the greatest damage
to structures is from landslides and ground subsidence, or the sinking of the ground triggered by vibrations
FireIn the San Francisco earthquake of 1906, most
of the destruction was caused by fires that started when gas and electrical lines were cut.
Tsunami Movement: ~600 mph in deep water
~250 mph in medium depth water
~35 mph in shallow water
Movement of a Tsunami
Tsunamis
Caused by the movement of the ocean floor– Causes a disruption in the water– Some are so wide that a large ship can
travel over the wave without knowing– Recent earthquake in the Indian Ocean
created a tsunamis that was 100 feet high and moving at 500 mph
Nepal The magnitude of the earthquake was 5.8Mw in the region.Bangladesh Earthquake was 10 km (6.2 miles) deep.
The Economics and Societal Impacts of EQs
Damage in Oakland, CA, 1989
• Building collapse• Fire• Tsunami• Ground failure
Effects of EQ on Sikkim Govt.1. The Sikkim Government has disbursed Rs 14.21
crore (142 million Rs) as relief among quake-hit people in Sikkim.
2. The India govt. has asked seismic experts from the IIT-Roorkee to conduct "earthquake impact studies" at the dam sites of state-owned NHPC Ltd and North Eastern Electric Power Corp. Ltd (Neepco).
4.Many roads are blocked by landslides 5. Indian Prime Minister Manmohan Singh immediately
convened a meeting of the National Disaster Management Authority Chamling to express his full support.
6. The Indian Air Force flew five cargo planes with relief material and rescue personnel for deployment in West Bengal and Sikkim.
RESCUE OPERATIONS
References:Sky newsNdtvGoogle earth Star news www.youtube.comwww.usgs.gov
Thank you
