Post on 07-Jul-2018
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Global Seismicity
(USGS)
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Crust
Mantle
Outer
Core
Inner
Core
Inside the Earth
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Local Convective Currents in the Mantle
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Pangea: Continents 200 million years ago
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Plate tectonic processes
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Mid-Ocean Ridge Spreading
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Major tectonic plates, mid-ocean ridges, trenches
and transform faults
(Bolt, 1993)
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Indo-
Australian
Plate
Pacific
Plate
Eurasian
PlateNorth American
Plate
South
American
Plate
AfricanPlate
Antarctic
Plate
Major Tectonic Plates on the Earth’s surface
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Convergent Boundary
Divergent Boundary
Transform Boundary
Types of Inter-Plate Boundaries
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Dip Slip
Faults
Strike SlipFaults
Type of Faults
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Stage A
Stage C
Slip
Stage B
Elastic Strain Build-Up and Brittle Rupture
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Time
(years)
StrengthEnergy
Build-Up
E l a s t
i c S t r e s s
Energy
Release
C u m u l a t i v e S l i p
C
A
Slip
AB
C
A
B
C
EQ
EQ
Time
(years)
EQ
Elastic Rebound Theory
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EQ
Surface Waves
Fault
Rupture
Body Waves
Structure
Soil
Geologic Strata
Arrival of Seismic Waves at a Site
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Direction of
Energy Transmission
Side to side
Up and down
P-WavesPush and pull
CompressionExtension
S-Waves
Love WavesSideways in horizontal plane
Rayleigh WavesElliptic in vertical plane
Motions caused by Body and Surface Waves
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StringMagnet
Pendulum Bob
Pen
Rotating
Drum
Chart Paper
Support
Direction of
Ground Shaking Recorded
Schematic of Early Seismograph
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Locating Earthquake
(Louie, 1996)
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Epicenter
Focus
Place of
Interest
Epicentral Distance
Fault
Rupture
Focal
Depth
Basic terminology
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Calculation of the Richter Magnitude (ML)of a Local Earthquake
(Bolt, 1993)
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R d i ill i ti ith di t
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Bright
(100 lumens)
Normal
(50 lumens)
Dull
(20 lumens)
Near
Far
100 Watt Bulb
Reducing illumination with distance
from an electric bulb
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IX
VIII
X
VII
Isoseismal Map of the 2001 Bhuj (India)
Earthquake (MSK Intensity)
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SEP 1999
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PGA from Intensity Data
• Guttenberg and Richter (1956)
log a = 0.333 I - 0.500
• Neumann (1954)
log a = 0.308 I - 0.041
• Trifunac and Brady (1975)
log a = 0.300 I - 0.014• Trifunac and Brady (1977)
log a = 0.350 I - 0.435
• Neuman (1977)
log a = 0.380 I - 0.560
• Murphy and O'Brien (1977)
log a = 0.250 I + 0.250
SEP-1999
0.010
0.10
1.0
4 5 6 7 8 9 10
G-R (1956)
N (1954)
T-B (1975)
T-B (1977) N (1977)
M-O'B (1977)
P G A
( g )
MMI
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0 10 20 30 40 50 60
0.5g
Time (sec)
1985 Mexico Earthquake (SCT 1A; N90E)
1940 Imperial Valley Earthquake (El Centro; S00E)
1971 San Fernando Earthquake (Pacoima Dam; N76W)
1991 Uttarkashi Earthquake (Uttarkashi, N75E)
Some typical recorded accelerograms
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Ground Motion Records
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Maximum Recorded PGA and PGV
(Martinez-Pereira, 1999)
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Deterministic Hazard Assessment
(Reiter, 1990)
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Probabilistic Hazard Assessment
(Reiter, 1990)
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Attenuation Curves
1979 Imperial Valley M~6.6 Earthquakes
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Preparing Zoning Maps
Source areas
• Historical earthquakes
• Known faults
• Chosen for discrete seismicity andrelated tectonic element
Recurrence Relations
• Extension of N-M from historical data
• Seismic activity of the area
Attenuation Relations
• Effect of eqk. (accn.) at each site due tooccurrence of eqk. in each source area
Probability of Exccedance
• Integrate effect of eqks. of diff. Sizes, atdiff. Sites at diff. probability ofoccurrence
Zoning Map
• Contours of equal intensity for aparticular probability of excceedance
Algermissen
Geographical Layout and
T t i Pl t B d i t I di
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Deccan Shield
Indo-
Gangetic
Plains
Himalayas
Peninsular
India
Bay of Bengal Arabian Sea
Indo-Australian
Plate
Eurasian Plate
Narmada
Plains
Godavari
Plains
MahanadiPlains
Tectonic Plate Boundaries at India
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<5
5<6
6<77<8
>8
Magnitude
2001 Bhuj
1934 Bihar-
Nepal
1905 Kangra
1950 Assam1897 Assam
Some Past Earthquakes
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Recent Past Indian Seismic Zone Map
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p
(IS:1893-1984)
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Current Indian Seismic Zone Map
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Current Indian Seismic Zone Map
(IS 1893-2001)
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