Three progresses reachhed in China
during this joint project

Tao Xiaxin
Harbin Institute of Technology， China

2013.6.18
Sendai The state-of-the-art of probabilistic Seismic Hazard
Assessment (PSHA) in the three countries as wellin the world is reviewed.
 We reach a common view to PSHA and the hazard
map that in some cases earthquake hazard maps
have done well at predicting the shaking from amajor earthquake; in other cases they have done
poorly.
 Wenchuan earthquake of China on May 12, 2008;
Tohoku earthquake of Japan on March 11, 2011:
are both very bad examples.

Area statistics of the Map 2001 of China
On the map
Actually occurred

Area with Intensity
0.1g or 0.15g

Area with Intensity
0.05g

Area with Intensity
Ⅷ (0.2g or 0.3g)
occurred

26996 km2

Area with Intensity
Ⅸ (0.4g or more)
occurred

15042 km2

2822 km2

0.43%

0.22%

Total area

3509184 km2

1274984 km2

0.77%

It seems not too bad, but more than 80000 people dead and $billions loss caused and dozens million people homeless.

Progress 1

 The main point is to predict the future largeearthquakes near big cities, especially those withmagnitude more than 7.
 To predict large earthquake with magnitude 8 ormore, one should watch quite large area, not fromstatistics in a small area.

Progress 1

 Even in subduction zone east of Japan with somany earthquake data, hazard of a shock 9.0 is
still not reliable if statistics worked just on the data
in small areas such as off Miyagi and off southern
Sariku.

Progress 1

Progress 1

Progress 1

 Chinese scientists presented a two or three rank
procedure to estimate seismicity parameters in alarge enough region and then assign occurrence
rates to individual potential source area by weighting
factors.
 Then the problem turns on the weighting, it is quitedifficult to evaluate the factor values from acomprehensive understand of the earthquake
occurrence from seismic, tectonic and crust dynamic
evidences, and a logical approach to add up
contributions of them is still required further study.

Progress 1

Two (three) rank potential source areadelineation
 The first rank PSA, seismic province or zone, for isquite large for enough data to statistics.
 The second rank PSA evaluated with its own upperbound magnitude, to be assigned with seismicity
parameters by a set of weighting factors.

 W  1 .0
iji

 The values of factors are evluated from acomprehensive summary
Wij   fijkk

 There is a query to sum up the all factor values
together.

Progress 1

 We are all on the way to a confident SHA, we know
something on occurrence of strong earthquake, but
can not really predict it in a scientific way even forlong-term, that fact is the reason of a P in PSHA.
 In nature P must come from statistical data, so themost principal contradiction in PSHA comes from thedetail hazard mapped for construction anddevelopment planning and quite large region forenough data.

 The ground motion attenuation in region withenough observation data, such as many regions in
China, is benefited to build a relationship fromsmall event records by earthquake observation
network with validation from strong motion data ofJapan.

Progress 2

 The idea to take into the deterministic synthesis
for the near field of strong earthquake in SHA istalked over during the project, and Chinese teampresent a procedure.
 In probabilistic seismic hazard assessment,
ground motion is estimated by means ofattenuation relationship that a kind of simplification,
taking magnitude for source mechanism, distancefor path of wave propagation, and the source isconsidered as a point.
 Ground motion at the near field of large
earthquake must be overestimated orunderestimated, since the energy from a quite
large source (rupture plane) is concentrated on apoint (hypocenter).

Progress 2

 Finite fault model is currently adopted in strong groundmotion synthesis to describe near-fault rupture
directivity effect and hanging wall effect which strongly
influence the distribution of ground motion amplitudes
on rock sites in the near fault region.
 The way to deal with a scenario earthquake is the key
step to build a link between PSHA and DSHA.
 To describe the probabilistic seismic hazard of a city,
scenario earthquake is widely adopted, with somestrong queries, since the difference between hazard
from an earthquake and that from earthquakes withvarious magnitudes in many areas.

Progress 2

潜源编号

40.00

80.00

120.0040.0001130.0018150.00240.00050.0001160.00090.0001170.0005190.000020

0.01590.0068210.00270.0003220.0001240.000025

0.00400.00080.0002290.00020.00000.00000.0034160.00200.00250.000.00170.00080.0002

Progress 2

Progress 2

Progress 20.1

回族土族自治县

0.1

皋兰县

0.15

西固区

0.4

永靖县

0.15
兰州市

0.3
0.2

0.2
榆中县

0.15

积石山保安族东乡族撒拉族自治县

东乡族自治县
临夏市临夏县

0.1
0.1广河县

Progress 3

Uncertainty correction of seismic hazard
3

P (Y C  y ) P(Yye)  f ( ) d  3

lgY  Co C1M C2M2 C3 lg(R C4eC5M ) C6R 

In general, the distribution
is truncated at -3σ to 3σ.

Progress 3

 The correction procedure is queried from the large
corrected result especially at hign Intensity.
 There are some problems could be deal with in deep: If the truncated range could be narrowed down further?
 If the distribution depends on magnitude?
 Or if it depends on distance?
 Or if it depends on ground motion amplitude, such asPGA?
 How to improve the uncertainty correction procedurewith any new findings.

Progress 3

Histograms of C-B, C-y and Id relations

Errors from Normal distribution of C-B, C-y and Id relations

Progress 3

The error distribution with magnitude of C-B, C-Y
and Id relation

No obvious variation with magnitude

Progress 3

The error distribution with distance of C-B, C-Y
and Id relation

No obvious variation with distanceProgress 3The error distribution with PGA of C-B, C-Y andId relation

Varies with PGA, the mean decreases of C-B , but
increases of C-Y and Id, while all standard deviation
increase.

Progress 3

New correction equation with error
distribution in segmentations

P(Yc  y )  3

3

P(Y  ye ) f y ( )d Progress 3

Seismic hazard curves corrected by C-B error
distribution for a site with high Intensity

Progress 3

Exceeding P in 50 Yrs

63.2%

10%2%

Uncorrected PGA

0.040

0.1210.234

Whole corrected PGA0.043

0.139

0.281

Segment corrected PGA

0.046

0.130

0.243

Progress 3

Seismic hazard curves corrected by C-B error
distribution for a site with moderate Intensity

Progress 3

Exceeding P in 50 Yrs

63.2%

10%

2%

Uncorrected PGA

0.015

0.080

0.131

Whole corrected PGA

0.017

0.083

0.170

Segment corrected PGA

0.018

0.081

0.154

Progress 3

Corrected seismic hazard curves for a site withlow Intensity

Progress 3

Exceeding P in 50 Yrs

63.2%

10%2%

Uncorrected PGA

0.011

0.042

0.066

Whole corrected PGA0.013

0.046

0.087

Segment corrected PGA

0.014

0.047

0.082

Acknowledgements
 We secerely thank the support by the National
Nature Science Foundation of China (51178151and 51178435), International Science &Technology Cooperation Program of China(2011DFA21460).

 The end Thank you for your attention！

 I am very sorry for not able to participate ourimportant annual meeting, also not able to meet
you this time.
 Hope to see you at Harbin, or somewhere in
China, or somewhere in the world.
 Have a successful meeting.
 Long distance Cheers from Harbin for all of yourhelth!