The second Meeting of JRCP, Jeju, Korea, 2012

Scenario earthquake- Link ofProbabilistic and Deterministic
SHA'sXiaxin TaoDoctor & Professor
School of Civil Engineering, Harbin Institute of Technology, China
Institute of Engineering Mechanics, CEAOcterber 29 - November 1, 2012

The second Meeting of JRCP, Jeju, Korea, 2012

Why combine the twoEngineering seismic hazard assessment, so called PSHA, is
now widely adopted in zoning maps at national, regional andcity level in the world.
In probabilistic seismic hazard assessment, ground motion
from earthquake with magnitude in interval Mj and in kth
potential area is estimated by means of attenuation
relationship.
The attenuation relation is a kind of simplification, taking
magnitude for source mechanism, distance for path of wave
propagation, and the source is considered as a point.
Ground motion at the near field of large earthquake must be
overestimated or underestimated, since the energy from aquite large source (rupture plane) is concentrated on a point(hypocenter).

The second Meeting of JRCP, Jeju, Korea, 2012

Why combine the two (cont. 1)Strong ground motion at near field is well known
complicated since it is governed by the source
predominately and the source of large earthquake is quite
complicated in general.
In that case, a rupture plane is needed to characterize thesource, for otherwise the ground motion tends to beoverestimated, and the near fault effect cannot besimulated.
Finite fault model is currently adopted in strong groundmotion simulation to describe near-fault rupture directivity
effect and hanging wall effect which strongly influence thedistribution of ground motion amplitudes on rock sites in thenear fault region.

The second Meeting of JRCP, Jeju, Korea, 2012

Why combine the two (cont. 2)

A new idea is proposed to combine the two approaches, thekey step is how to establish a link between the two.
Benefit of seismic zoning map is mainly from mitigation of loss
and casualty in cities in large earthquake.
To describe the probabilistic seismic hazard of a city, scenario
earthquake is widely adopted, with some strong queries,
since the difference between hazard from an earthquake andthat from earthquakes with various magnitudes in manyareas.

The second Meeting of JRCP, Jeju, Korea, 2012

How to build a link
The way to deal with a scenario earthquake is the key stepto build a link between PSHA and DSHA.
This is seismic hazard curves of a city in case study byPSHA

The second Meeting of JRCP, Jeju, Korea, 2012

Uncertainty correction of seismic hazard
3

P(YC  y )   P(Y  y  e  )  f ( )d3lg Y  Co  C1M  C2 M 2  C3 lg( R  C4eC5M )  C6 R  潜源编号

10.00

40.00

80.00

120.00160.00200.00250.00300.00400.00600.0010.00100.00000.00000.00000.00000.00000.00000.00000.00000.000020.0005

0.00000.00000.00000.00000.00000.00000.00000.00000.000030.00020.00000.00000.00000.00000.00000.00000.00000.00000.000040.0058

0.00010.00000.00000.00000.00000.00000.00000.00000.000050.00110.00000.00000.00000.00000.00000.00000.0000

0.00000.00006

0.01650.00000.00000.00000.00000.00000.00000.00000.00000.00007

0.00650.00000.00000.00000.00000.00000.00000.00000.00000.000090.00150.00000.00000.00000.00000.00000.00000.00000.00000.0000100.00170.00000.00000.00000.00000.00000.00000.00000.00000.000012

0.00810.00000.00000.00000.00000.00000.00000.00000.00000.000013

0.00830.00180.00000.00000.00000.00000.00000.00000.00000.000014

0.00030.00000.00000.00000.00000.00000.00000.00000.00000.000015

0.01200.00240.00050.00010.00000.00000.00000.00000.00000.000016

0.01210.00090.00010.00000.00000.00000.00000.00000.00000.0000170.00600.00050.00000.00000.00000.00000.00000.00000.00000.000019

0.00240.00000.00000.00000.00000.00000.00000.00000.00000.000020

0.06270.01590.00680.00340.00170.00080.00020.00000.0000

0.000021

0.02000.00270.00030.00000.00000.00000.00000.00000.00000.000022

0.00330.00010.00000.00000.00000.00000.00000.00000.00000.000024

0.00210.00000.00000.00000.00000.00000.00000.00000.00000.000025

0.02100.00400.00080.00020.00000.00000.00000.00000.00000.000026

0.00280.00000.00000.00000.00000.00000.00000.00000.00000.000027

0.00070.00000.00000.00000.00000.00000.00000.00000.00000.0000

28

0.00250.00000.00000.00000.00000.00000.00000.00000.00000.000029

0.00400.00020.00000.00000.00000.00000.00000.00000.00000.000030

0.00380.00000.00000.00000.00000.00000.00000.00000.00000.000031

0.00060.00000.00000.00000.00000.00000.00000.00000.00000.000032

0.00100.00000.00000.00000.00000.00000.00000.00000.00000.000033

0.00050.00000.00000.00000.00000.00000.00000.00000.00000.000034

0.00660.00000.00000.00000.00000.00000.00000.00000.00000.000036

0.00080.00000.00000.00000.00000.00000.00000.00000.00000.000037

0.00010.00000.00000.00000.00000.00000.00000.00000.00000.0000

潜源编号

10.00

2

0.000530.000240.005850.001160.016570.006590.0015100.0017120.008113

0.0083140.0003150.0120

16

40.00

80.00

120.000.00240.00050.00010.01210.00090.0001170.00600.0005190.00240.0000

20

0.06270.01590.0068210.02000.00270.0003220.00330.000124

0.00210.000025

0.02100.00400.00080.000226

0.0028270.000728

0.002529

0.00400.00020.00000.000030

0.0038310.000632

0.001033

0.000534

0.0066360.0008370.0001160.00200.00250.000.00170.00080.00020.00010.00180.0034300.00

潜源编号

40.00

4

0.0001130.001815

80.00

120.000.00240.00050.0001160.00090.0001170.0005190.000020

0.01590.0068210.0027

0.0003220.0001

240.0000

250.0040

0.00080.0002290.0002

0.00000.00000.0034160.00200.00250.000.00170.00080.0002

The second Meeting of JRCP, Jeju, Korea, 2012

The second Meeting of JRCP, Jeju, Korea, 2012

Exceeding
Probability

63% in 50 years

10% in 50 years

2% in 50 years

PGA（gal）

59

192

345

Magnitude

5.7

6.5

7.0

Distance
（km）

30

2116

Maxianshan
North Fault

Western
segment ofMaxianshan
North Fault

Midele andEasternsegments ofMaxianshan
North Fault

Causativefault0.1治县

皋兰县

0.15

0.15
西固区

0.4

兰州市

永靖县

0.3
0.2

0.2
榆中县

0.15

安族东乡族撒拉族自治县

临夏县

0.1

东乡族自治县
临夏市

0.10.1广河县

0.1族土族自治县

皋兰县

0.15

西固区

0.4

兰州市

永靖县

0.30.2

榆中县积石山保安族东乡族撒拉族自治县

0.15
东乡族自治县

临夏市 0.1

临夏县广河县

The second Meeting of JRCP, Jeju, Korea, 2012Conclusion










A new idea is proposed to combine the PSHA and DSHA
approaches for the next generation map.
Scenario earthquake is emphasized as the key step toestablish a link between the two.
From a case study, the detail hazard result by mean
attenuation relation is examined, and the most potential
source area is acquired for a given exceeding probability.
A distance range is then fixed from the segmentation of themain active fault in the source area, and the corresponding
magnitude is calculated from the PGA by PSHA by themean attenuation law.
The magnitude is checked from the upper bond magnitudeof the potential area.

The second Meeting of JRCP, Jeju, Korea, 2012Conclusion (cont.1)
Finite fault source model is built from the checkedmagnitude with the fault data as much as possible.
30 source models are presented to take into accountuncertainty on global and local parameters.
The ground motions at near field are synthesized, andaverage PGA is assigned to each rock site, and soil site aswell by taking site condition into account further.
The isoseismials constructed from the synthesized motion
field is overlaid on that from PSHA, and the two aremerged together as the final map by replacing the PSHA
result at near field by the synthesized one.

The second Meeting of JRCP, Jeju, Korea, 2012Conclusion (cont.2)







By this way, the scenario is the maximum confidential, fromseismotectonic condition, the corresponding PGA by meanattenuation relation is the same as the PSHA result by thesame relation.
In this meaning, the isoseismals from the scenarion could
be considered with that exceeding probabilitty of the PSHA
result, and can merged with that together.
The uncertinty on source model has been taken into
account, and that on attenuation could also be taken into
account by the same way to synthesize more motion fields
from each source model with different values of random
error term in attenuation law.
The hign intensity area on the map is shifted now
westwards reasonably as an improvement.
The number of synthesis is determined by the stability of themean PGA.

The second Meeting of JRCP, Jeju, Korea, 2012

Thank you!
 Taoxiaxin@yahoo.com.cn

The second Meeting of JRCP, Jeju, Korea, 2012

Seismic hazard of a city by PSHA