Majjqor Hazards of Earthquakes -...
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Major Hazards of Earthquakes Major Hazards of Earthquakes Ground Motion Ground Motion: Shakes structures causing : Shakes structures causing th t ll th t ll them to collapse them to collapse Liquefaction Liquefaction: Conversion of formally stable : Conversion of formally stable h i l il t fl id i h i l il t fl id i cohesionless soils to a fluid mass, causing cohesionless soils to a fluid mass, causing damage to the structures damage to the structures Landslides Landslides: Triggered by the vibrations : Triggered by the vibrations Landslides Landslides: Triggered by the vibrations : Triggered by the vibrations Fire Fire : Indirect result of earthquakes triggered : Indirect result of earthquakes triggered by broken gas and power lines by broken gas and power lines by broken gas and power lines by broken gas and power lines Tsunamis Tsunamis: large waves created by the : large waves created by the instantaneous displacement of the sea floor instantaneous displacement of the sea floor instantaneous displacement of the sea floor instantaneous displacement of the sea floor during submarine faulting during submarine faulting
Transcript of Majjqor Hazards of Earthquakes -...
Major Hazards of EarthquakesMajor Hazards of Earthquakesj qj q Ground MotionGround Motion: Shakes structures causing : Shakes structures causing
th t llth t llthem to collapse them to collapse LiquefactionLiquefaction: Conversion of formally stable : Conversion of formally stable
h i l il t fl id ih i l il t fl id icohesionless soils to a fluid mass, causing cohesionless soils to a fluid mass, causing damage to the structuresdamage to the structures
LandslidesLandslides: Triggered by the vibrations: Triggered by the vibrations LandslidesLandslides: Triggered by the vibrations: Triggered by the vibrations FireFire : Indirect result of earthquakes triggered : Indirect result of earthquakes triggered
by broken gas and power linesby broken gas and power linesby broken gas and power linesby broken gas and power lines TsunamisTsunamis: large waves created by the : large waves created by the
instantaneous displacement of the sea floorinstantaneous displacement of the sea floorinstantaneous displacement of the sea floor instantaneous displacement of the sea floor during submarine faultingduring submarine faulting
Damage due to EarthquakesDamage due to EarthquakesEarthquakes have varied effects, including changes in geologic features damage to man-made structures
g qg q
Earthquake Damage depends on many
geologic features, damage to man-made structures and impact on human and animal life.
The size of the EarthquakeEarthquake Damage depends on many
factors:
The distance from the focus of the earthquake The properties of the materials at the site The nature of the structures in the areaThe nature of the structures in the area
Ground ShakingGround Shaking
Frequency of shaking differs for different seismic waves. Frequency of shaking differs for different seismic waves. q y gq y g
High frequency body waves shake low buildings more. High frequency body waves shake low buildings more.
Low frequency surface waves shake high buildings more. Low frequency surface waves shake high buildings more.
Intensity of shaking also depends on type of subsurface material.Intensity of shaking also depends on type of subsurface material.
Unconsolidated materials amplify shaking more than rocks do. Unconsolidated materials amplify shaking more than rocks do.
B ildi d diff tl t h ki d diB ildi d diff tl t h ki d diBuildings respond differently to shaking depending on Buildings respond differently to shaking depending on construction styles, materials construction styles, materials
Wood Wood ---- more flexible, holds up well more flexible, holds up well
Earthen materials, unreinforced concrete Earthen materials, unreinforced concrete ---- very vulnerable to very vulnerable to shaking. shaking.
Earthquake Destruction: Ground Shaking
Collapse of Buildings
Earthquake Destruction: Ground Shaking
Image of Bachau in Kutch region of Gujarat after earthquakeearthquake
Earthquake Destruction: Ground Shaking
Building design: Buildings that are not Building design: Buildings that are not designed for earthquake loads suffer moredesigned for earthquake loads suffer more
Earthquake Destruction: Ground Shaking
Causes failure of lifelines
Earthquake Destruction: Landslides
Earthquake Destruction: Liquefaction
Flow failures of structures are caused by loss of strength of underlying soil
Nishinomia Bridge 1995 Kobe earthquake, Japan
Earthquake Destruction: Liquefaction
Sand Boil: Ground water rushing to the surface due to liquefaction
Sand blow in mud flats used for salt production southwest of Kandla Port, Gujarat
Earthquake Destruction: Liquefaction
Lateral Spreading: Liquefaction related phenomenon
Upslope portion of lateral spread at Budharmora, Gujarat
Earthquake Destruction: Liquefaction
Lateral spreading in the soil beneath embankment causes the embankment to be pulled apart, producing the large crack down the center of the road.
Cracked Highway, Alaska, 1964
Earthquake Destruction: Liquefaction
Liquefied soil exerts higher pressure on retaining walls,which can cause them to tilt or slide.
Earthquake Destruction: Liquefaction
Increased water pressure causes collapse of dams
Earthquake Destruction: Fire
Earthquakes sometimes cause fire due to broken gascause fire due to broken gas lines, contributing to the loss of life and economy.
The destruction of lifelines and utilities make impossible forutilities make impossible for firefighters to reach fires started and make the situation worseeg. 1989 Loma Prieta g
1906 San Francisco
Earthquake Destruction: Tsunamis
Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the overlying watervertically displaces the overlying water. The water above the deformed area is displaced from its equilibrium position. Waves are formed as the displaced water mass, which acts under the influence of gravity, attempts to regain its equilibrium. Tsunami travels at a speed that is related to the water depth - hence, as th t d th d th t i lthe water depth decreases, the tsunami slows. The tsunami's energy flux, which is dependent on both its wave speed and wave height, remains nearly constant.and wave height, remains nearly constant. Consequently, as the tsunami's speed diminishes as it travels into shallower water, its height grows. Because of this effect, a tsunami, imperceptible at sea, may grow to be several meters or more in height near the coast and can flood a vast area.
TsunamiTsunami Movement: Tsunami Movement: ~~600 600 mph in deep watermph in deep water
~~250 250 mph in medium depth watermph in medium depth water
~~35 35 mph in shallow watermph in shallow water
Earthquake Destruction: Tsunamis
The tsunami of 3m height at Shikotan, Kuril Islands, 1994 carried this vessel 70 m on-shore. The waves have eroded the soil and deposited debris.
Geomorphological ChangesGeomorphological Changes
•Geomorphological changes are often caused by an earthquake: e g movements--either vertical or horizontal--earthquake: e.g., movements--either vertical or horizontal--along geological fault traces; the raising, lowering, and tilting of the ground surface with related effects on the flow of
d tgroundwater;
•An earthquake produces a permanent displacement across the faultthe fault.
•Once a fault has been produced, it is a weakness within the rock and is the likely location for future earthquakesrock, and is the likely location for future earthquakes.
•After many earthquakes, the total displacement on a large fault may build up to many kilometers, and the length of the y p y , gfault may propagate for hundreds of kilometers.
List of Major Historic EarthquakesList of Major Historic EarthquakesYearYear LocationLocation DeathsDeaths MagnitudeMagnitude
15561556 ChinaChina 55,,3030,,000000 88..0019061906 San FranciscoSan Francisco 700700 77..9919601960 S. ChileS. Chile 22,,230 230 99..5519641964 AlaskaAlaska 131 131 99..2219761976 ChinaChina 77,,0000,,000 000 77..88,, ,,19851985 Mexico CityMexico City 99,,500 500 88..1119891989 CaliforniaCalifornia 6262 77 1119891989 CaliforniaCalifornia 62 62 77..1119951995 KobeKobe 55,,472 472 66..9920012001 GujaratGujarat 11 0000 000000 66 9920012001 Gujarat, Gujarat,
IndiaIndia11,,0000,,000000 66..99
DATE EPICENTRE LOCATION MAGNITUDE
LIST OF SOME SIGNIFICANT EARTHQUAKES IN INDIA AND ITS NEIGHBOURHOOD
LOCATION MAGNITUDELat( Deg N ) Long( Deg E )
1819 JUN 16 23.6 68.6 KUTCH,GUJARAT 8.0
1869 JAN 10 25 93 NEAR CACHAR, ASSAM 7.5
1885 MAY 30 34.1 74.6 SOPOR, J&K 7.0
1897 JUN 12 26 91 SHILLONGPLATEAU 8.7
1905 APR 04 32.3 76.3 KANGRA, H.P 8.0
1918 JUL 08 24.5 91.0 SRIMANGAL, ASSAM 7.6
1930 JUL 02 25.8 90.2 DHUBRI, ASSAM 7.1
1934JAN 15 26.6 86.8 BIHAR-NEPALBORDER 8.3
1941 JUN 26 12.4 92.5 ANDAMAN ISLANDS 8.1
1943 OCT 23 26.8 94.0 ASSAM 7.2
1950 AUG 15 28.5 96.7 ARUNACHAL PRADESH-CHINA BORDER
8.5
1956 JUL 21 23.3 70.0 ANJAR, GUJARAT 7.0
1967 DEC 10 17.37 73.75 KOYNA, MAHARASHTRA 6.5
1975 JAN 19 32 38 78 49 KINNAUR HP 6 21975 JAN 19 32.38 78.49 KINNAUR, HP 6.2
1988 AUG 06 25.13 95.15 MANIPUR-MYANMAR BORDER 6.6
1988 AUG 21 26.72 86.63 BIHAR-NEPAL BORDER 6.4
1991 OCT 20 30.75 78.86 UTTARKASHI, UP HILLS 6.6
1993 SEP 30 18 07 76 62 LATUR-OSMANABAD 6 31993 SEP 30 18.07 76.62 LATUR OSMANABAD, MAHARASHTRA
6.3
1997 MAY 22 23.08 80.06 JABALPUR,MP 6.0
1999 MAR 29 30.41 79.42 CHAMOLI DIST, UP 6.8
2001 JAN 26 23.40 70.28 BHUJ , GUJARAT 6.9
