EARTHQUAKE IN BANGLADESH

MD. ABU BAKKAR SIDDIQUEF.H-028

Outline

EarthquakeHow does an EarthquakeCauses of EarthquakeTectonic Position of BangladeshHistorical Earthquake of BangladeshThe Earthquake Risk of BangladeshEarthquake Mitigation Program

Earthquake

Earthquake is a the result of sudden release of energy in the Earth’s crust that creates seismic waves.It is one of the most horrific and devastating natural phenomena which can cause great damage to the areas it take place in , prolonged economic chaos and even kills scores of innocent people.

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How does an earthquake happen?

• There are about 20 plates along the surface of the earth that move continuously and slowly past each other. When the plates squeeze or stretch huge rocks form at their edges and rocks shift with great force, causing an earthquake. As the plates move they put forces on themselves and each other. when the force is large enough, the crust is forced to break. When the break occurs the stored stress is released as a form of wave and makes the ground shake.

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• For example: If you throw stone in a pond of

still water, series of waves are produced on the surface of water, these spread out in all directions from the point the stone strikes.

Similarly , Any sudden disturbances in the earth’s crust may produce vibration which travel in all direction from the point of disturbances.

Causes of Earthquake

Natural CausesInter plates EarthquakeIntra plates EarthquakeVolcanic EarthquakeLandslide EarthquakeInduced CausesReservoir-Induced EarthquakeMining and Groundwater ExtractionFossil Fuel Extraction

Earthquake

The terms related to Earthquake Focus(Hypocenter): Focus is the point on the

fault where rupture occurs and the location from which seismic waves are released.

Epicenter: Epicenter is the point on the

earth’s surface that is directly above the focus, the point where an earthquake or underground explosion originates.

The terms related to Earthquake Fault Line: A fault line is the surface trace of

a fault, the line of intersection between the earth’s surface.

Fault plane: Fault plane are the cracks or

sudden slips of land. Fault Scarp: A Fault Scarp is the topographic

expression of faulting attributed to the displacement of the land surface by movement along faults.

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Tectonic Position of Bangladesh

Bangladesh and Ganges Brahmaputra delta lies at the junction of three plates: the Indian plate, the Eurasian plate and the Burma platelet.

Bangladesh is bounded by the Shillong plateau to the north, Indian shield to the west, the Indo-Barman ranges to the east and Bay of Bengal to the south that make the complex geographical position.

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Cont……

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Indian plate is moving to the northeast direction at the rate of 6cm per year and subducting under the Eurasian plate and Burmese plate at a rate of 45 mm and 35 mm per year respectively that continues the uplift of Himalayan Arc and Indo-Barman Arch.

(source: banglaPIRE)

Source: Shankor Roy

Probable Earthquake Sources

Name Maximum Magnitude (Estimation)

Bogra Fault Zone 7.0

Tripura Fault Zone 7.0

Sub Dauki Fault Zone 7.0

Assam Fault Zone 8.5

Shillong Plateau 7.0

Modhupur Fault Zone 7.5

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Earthquake zone of Bangladesh

Zone 1:High RiskMymensing,Sylhet,Rangpur,Lal

monirhat, Kurigram etc Zone 2:Moderate RiskBogra, Dinajpur, Dhaka,

Comilla, panchgar etc Zone 3:Low RiskKhulna, jessor, Barisal,

Patuakhali etc.

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Earthquake and Dhaka City Geologically active faults within

50 to 500km distance from Dhaka .Dhaka is among the 20 major

world cities that are the greatest risk from earthquakes

Some of these earthquakes especially the 1762, 1812, 1865, 1885 and 1897 happened in Dhaka. If 7-8 grade in Richter Scale earthquake happen in Dhaka 70-80 percent concrete structures would just collapse and 30,00,000 peoples will die.

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Historical Earthquake in BangladeshYear Name Magnitude Distance from

Capital(km)Affected Area

1869 Cachar Earthquake

7.5 250 Assam, Monipur, Sylhet

1985 Bengle Earthquake

7.0 170 Jamalpur, Mymensing, Bogra

1897 Great Indian Earthquake

8.7 230 Assam, Sylhet, Rangpur

1918 Srimangal Earthquake

7.6 150 Whole Sylhet to Dhaka

1930 Dubri Earthquake

7.1 250 Rangpur

1934 Bihar-Nepal Earthquake

8.3 510 Nepal, India, Bangladesh

1950 Assam Earthquake

8.5 780 Assam, Whole Bangladesh

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Year Name Maqgnitude Distance from Capital(km)

Affected Area

1987 Sylhet Earthquake

5.6 200 Northern Bangladesh

1997 Bandarban Earthquake

6.0 325 South-eastern part

1999 Maheskhali Earthquake

5.1 350 Maheskhali

2003 Barkal Earthquake

5.1 350 Barkal

2015 Nepal Earthquake

7.9 745 Nepal, India, Bangladesh

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Nepal Earthquake

• 25th April, 2015 Nepal, India, Bangladesh experienced a devastated earthquake with 7.9 magnitude which caused about 10,000 loss of lives in Nepal and India, 4 died including 8 injured in our country.

• The epicenter was at Pokhara which is 745 km away from our capital. It was felt 4-5 magnitude in our country.

• Now the ?? arises what will happen if such kind of earthquake strikes in country.

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What may happen if a major earthquake crop up

• Collapse of poorly constructed or old building• Possible damage of power installations• Water supply failure• Damage of roads and blockage of traffic• School building and hospital may collapse• Fire may come out causes of leakage of gas

line and short circuit• Huge loss of lives and property

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The Earthquake Risk of Bangladesh

• The tectonic location• The huge number of population• The unplanned buildings over the city• The week infrastructure• The different types of faults• Less consciousness of people• Less planning of government• Economical lacking• Lack of land use planning

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Mitigation: Organization Involvement

• Ministry of disaster and management• Institute of Earthquake Engineering

Research(IEER), Chittagong• Dhaka University Earth and Observatory

Center• Bangladesh Earthquake Society(BES)• Geological Survey of Bangladesh(GSB)• Action Aid Bangladesh(AAB)• Bangladesh Concrete Society(BCS)

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The Earthquake Mitigation Program

Build the Foundation Development of an institutional structure Information and Communication Technology Technical Review and Analysis

Training and Capacity Building Building Code Formulation, Enforcement and Implementation Earthquake Resilient Training and certification Pilot Structure Construction with Resiliency to Earthquake

Finalize the Elements of Strategy Land use planning Earthquake hazard, Vulnerability and Risk analysis Legal and Institutional arrangements (source: SARDRM)

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