Earthquake Risk Reduction Hazard, Vulnerability & Risk Assessment

Earthquake Risk Reduction 111

Earthquake Risk Reduction 　

Hazard, Vulnerability & Risk Assessment

Session 2World Bank Institute

Charles SCAWTHORN Junji KIYONO

Kyoto University


SystemInput

Earthquake

Human/Social

Environment

Damage

Output

Hazard Vulnerability

Loss

Assessment

Outline of Risk Assessment

Keywords: Seismic Hazard, Attenuation, Hazard, Vulnerability, Loss Estimation


Seismic Hazards

faulting

tsunamishaking

faulting

fire

landslide

liquefaction


Liquefaction -1


(Map Source: PHIVOLCS)

Liquefaction Susceptibility


Tsunami


Tectonics and Active Faults in the Philippines


Detailed Fault Map

Valley Fault System, Pasig Quadrangle

1:10,000

(Source: PHIVOLCS)


Historical Seismicity, 1608-1985, Metro Manila Region

(Source: MMEIRS, 2003)


mbamN )(log

Gutenberg-Richter relation (b-value model):

4 5 6 7 8 Mw

N(m)

1.0

0.1

0.01

0.001

Magnitude-frequency relation is the N(m), the number of events equal to or greater than magnitude m. a is a regional constant, and b expresses the rate of seismicity. The simplest M-f relation is the Gutenberg-Ricter relation:

mbamN )(log


Attenuation

Campbell, K.W. and Bozorgnia, Y. 2003. “Updated Near-Source Ground Motion (Attenuation) Relations for the Horizontal and Vertical Components of Peak Ground Acceleration and Acceleration Response Spectra,” Bull. Seismol. Soc. Am.


Seismic Hazard Assessment

Map faults

Estimate EQ occurrence rates

Estimate attenuation

Combine data to estimate Hazard Curve

Provide various measures of the Hazard

PGA

Pe pa

Hazard Curve


Hazard Maps (Source: MMEIRS)

Scenario Shaking Map

Liquefaction Potential Map


Seismic vulnerability is the degree of loss causedby a given level of hazard.

Seismic vulnerability is a function of ground motion or other hazard intensities.

Typically, the most seismically vulnerable buildings are earthen and low-strength unreinforced masonry, such as stone and brick.

Other vulnerable types of buildings are older reinforced concrete buildings, and buildings with large ground floor openings.

Seismic Vulnerability


Vulnerability of Reinforced Concrete Buildings - 1

Ordinary RC column in non-seismic area –few ‘lateral’ ties surrounding the longitudinal reinforcement

Ductile RC column for seismic area – many

‘lateral’ ties surrounding the

longitudinal reinforcement


Vulnerability of Reinforced Concrete Buildings - 2

failed RC column on highway bridge1994 Northridge (US) earthquake

collapse of RC multistory hotel Baguio, 1990 Philippines

Broken RC column in collapsed building, 2005 SouthAsia earthquake – note small diameter lateral ties spaced far apart

Lateral ties


Vulnerability can be represented as (a) a damage rate of buildings in a area, or as (b) a damage degree for a building itself.

Dam

age

rate

0%

50%

100%

Partial damageHeavy damage

Collapse

Seismic intensity

Dam

age

degre

e

0.0

0.5

1.0

Partial damage

Heavy damage

Collapse

Seismic intensity

Type I

Type II

Vulnerability function


Mean Damage Functions

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

VI VII VIII IX X

MMI

LOW RISE WOOD FRAME

MED RISE RC SHEAR WALL (W/O MRF)

MED RISE BRACED STL FRAME

MED RISE R MOM RESISTG. NON-DUCT. RCFRAME-D

URM (BRG. WALL) LOW RISE (1-3 )

Example Vulnerability Functions


Risk, probabilistic distribution of loss, can be estimated by combining vulnerability functions with the hazard data as shown in the following schematic figure.

Total annual expected cost experiencing severity of ground motion larger than a* is derived from a product of hazard and vulnerability. Hatched area is risk.

a*

Dam

age (

cost

rati

o)

when e

xperi

ence

se

veri

ty, a

0.0

0.5

1.0

Ground motion

severity, aC

ontr

ibuti

on o

f each

level

of

severi

ty t

o t

ota

l annual

cost

Ground motion

severity, a

Annual pro

babili

ty o

f experi

enci

ng s

everi

ty larg

er

than a

Ground motion

severity, a

p

a*

Hazard Vulnerability

Risk

Earthquake Risk - 1


Earthquake risk is the uncertainty of loss over a specific future time.

Generally, risk is determined as:[R]i = [H]j x [V|H]ij

In which [R]i is the risk, probability or average rate of loss of

elementi due to earthquake intensity j,

[H]j the hazard, probability or average expected rate of experiencing earthquake intensity j, and

[V|H]ij the vulnerability, the level of loss that would be causedto element i given Hazard j (ie, as a result of experiencing earthquake shaking of severity j)

Earthquake Risk - 2


Risk Assessment

0.0001

0.001

0.01

0.1

1

5 6 7 8 9 10 11

MMI

Pro

b o

f E

xcee

dan

ce p

a

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

120.0%

Dam

age

Pe pa

Damage | MMI

0.0001

0.001

0.01

0.1

1

5 6 7 8 9 10 11

MMI

Pro

b o

f E

xcee

dan

ce p

a

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

120.0%

Dam

age

Pe pa

Damage | MMI

Example

A site’s seismicity is equivalent to MMI every 10 years, MMI 7 every 50 years, etc. On the site, a building will experience 0.1% loss given MMI 6, etc, see Table and graph.

Due to the range of seismicity, the average loss per year is 0.28%, as shown in the Table

MMI Pe pa pdf pa Damage | MMI Damage6 0.1 0.08 0.1% 0.000087 0.02 0.018 10% 0.00188 0.002 0.001 20% 0.00029 0.001 0.0005 50% 0.0002510 0.0005 0.0005 100% 0.0005

E(D) = 0.00283

MMI Pe pa pdf pa Damage | MMI Damage6 0.1 0.08 0.1% 0.000087 0.02 0.018 10% 0.00188 0.002 0.001 20% 0.00029 0.001 0.0005 50% 0.0002510 0.0005 0.0005 100% 0.0005

E(D) = 0.00283


Loss Estimation Software

There are several software programs that can be used to estimate seismic risk. These include: REDAS (Rapid Earthquake Damage Assessment System), PHIVOLCS) HAZUS, available from www.nibs.org RADIUS, available from www.unisdr.org or

Documents

Earthquake Risk Reduction Hazard, Vulnerability & Risk Assessment