# Presentation: 818051

## National Seismic Hazard Mapping Project of JAPAN

**National Research Institute for Earth Science and Disaster Prevention (NIED)**
**Hiroyuki Fujiwara**

## Background of the Project

**Headquarters of Earthquake Research Promotion**** was established in accordance with ****Earthquake Disaster Management Special Measures Act**** (1995).**
**Promotion of Earthquake Research**
-     **-****Comprehensive and Fundamental Measures for Promotion of Observation, Measurement and Research on Earthquakes****-(****April 23, 1999****)**
-  **Earthquake research requiring immediate promotion**
**1.****Preparation of seismic hazard maps based on surveys of active faults, long-term evaluations of the probability of earthquake occurrence, and evaluations of strong ground motion**
**2.****Promotion of real-time transmission of earthquake information**
**3.****Improvement of observation system for earthquake disaster prevention**
**4.****Promotion of observation and research for earthquake prediction**

## Structure of the Headquarters for  Earthquake Research Promotion

**Headquarters**

**Policy Committee**

**Earthquake Research**
** ****Committee**

**Subcommittee for Survey and **
**Observation Plans**

**Budget Subcommittee**

**Subcommittee for **
**Long-term Evaluations**

**Subcommittee for Evaluations of**
**Strong Ground Motion**

**Subcommittee for Instituting **
**Results in Society**

## Advanced map

**Surveys for       active faults**

**Surveys for               underground structure**

**Long-term evaluations**

**Evaluation of methods for prediction of strong-motion**

**Study on methods****  ****to make probabilistic seismic hazard maps**

**Study on methods****  ****to make scenario earthquake maps**

**Evaluations of Strong-motion**

**General Seismic Hazard Map covering the whole Japan**

-  **Duties of NIED**

**Duties of Earthquake Research committee**

**Publication system                      for hazard maps**

## Seismic hazard mapping project in NIED

**Development of publication system for seismic hazard maps **

-  **Study on deaggregation**

**Study on scenario earthquake maps**

-  **Study on probabilistic seismic hazard maps**

## Probabilistic Seismic Hazard Map

- An example of seismic hazard maps has shown information predicting possibility that a certain area is attacked by strong ground motion in a certain term by means of probability. (Comprehensive Fundamental Measures, 1999)

- ・It is what has exhibited, by fixing two   parameters among term, strong-motion level and probability, distribution of remaining one on the map.
- ・Use of occurrence probability of each earthquake.
- ・All possible earthquakes are considered.
- ・It does not show ground motion caused by an earthquake at the same time.

-  Example of probabilistic map

**Feature**

## Flowchart of SHA

- Modeling of seismic activity
- (Earthquake research committee)

## Strong-motion evaluation in SHA

- Modeling of seismic activity

- Site amplification
- (Matsuoka & Midorikawa 1994)

- PGV on the engineering bedrock

- PGV on the ground surface

- JMA seismic intensity

- Empirical formula
- (Midorikawa et al. 1999)

- Attenuation relation
- (Si & Midorikawa 1999)

## Probabilistic Seismic Hazard Maps

**Probabilistic Seismic Hazard Maps**

## Probabilistic Seismic Hazard Maps

**Major 98 active fault zones and the occcurance areas of the subduction earthquakes considered to study the seismic hazard map in western part of Japan**

**Probabilistic Seismic Hazard Maps**

## Example of long-term evaluation of earthquake activity

| Average recurrence interval (L)  | Elapsed time since the latest earthquake
(T) | Occurrence probability in 30 years (P) |
| --- | --- | --- |
| 1900 years ~
4500 years | 2400 years ~2800 years |  0.09% ~ 9% |

- (Western Lake Biwa Fault zone)

## In 98 major active fault zones, 11 large earthquakes  occurred in last 200 years. Average interval is 18.4 years.

- How should we treat the occurrence probability given by an interval?

- In 98 major active fault zones, 11 large earthquakes  occurred in last 200 years. Average interval is 18.4 years.
- (Earthquake Research Committee of Japan)

## How to calculate P from L and T given by intervals?

- 1.P(Lmin,Tmax)  (Maximum case)
- 2.P(Lmed,Tmed) (Median case)
- 3.
- 4.(P(Lmin,Tmax)+P(Lmax,Tmin))/2

## Case 1            11.6 / 200 years 

- Case 1            11.6 / 200 years

- Case 2                 6.1 / 200 years

- Case 3                        5.7 / 200 years

- Case 4                               7.7 / 200 years

## (Case 2)

- (Case 1)

- JMA seismic intensity of 3% in 30 year probability of exceedance (earthquakes in 98 major fault zones)

## Scenario Earthquake Shake Maps

**Scenario Earthquake Shake Maps**

**Seismic hazard maps with specified seismic source fault**

- Distribution of peak ground velocity on the engineering bedrock.

- Distribution of JMA seismic intensity on the ground surface.

## Scenario Earthquake Shake Maps 

## Theoretical approach for evaluation of strong-motion

**Amplification due to**
** ****thick sediment **

**Amplification due to soft soil near surface**

**Wave propagation in a heterogeneous medium**

**Complicated source process**

## Hybrid method for evaluation of strong-motion 

**Low frequency range**

**High frequency range**

- 低周波+高周波

- Hybrid method for evaluation of strong-motion

**deterministic**

** ****Stochastic **

**Finite Difference Method**

**Stochastic Green’s function method**

**Superposition**

**Low frequency range**

**High frequency range**

**Matching filter**

## Characterized Source Model

**Complicated source model**** **

**Characterized source model**

**Characterized source model for Nankai Earthquake**

**Characterized source model for Tonankai Earthquake**

## Modeling of underground structure 

- Flowchart of structure modeling

- In modeling of underground structure, we consider the deep underground structure from the crust and plates up to seismic bedrock (Vs=3km/s), the structure of sediments from the seismic bedrock up to engineering bedrock (Vs=400m/s~700m/s), and the structure of surface soils from the engineering bedrock up to the ground surface.

## Verification of methodology for strong-motion evaluation of earthquakes in plate boundaries.

- The Tokachi-oki earthquake (MJMA8.0) struck the northern
- Japanese island of Hokkaido on 26th September 2003.
- The 2003 Tokachi-oki earthquake was the first large interplate
-  earthquake recorded by the nation-wide strong-motion networks,
- K-NET and KiK-net.

## The 2003 Tokachi-oki earthquake (2003 9/26  Mj 8.0)

## Rupture process of the 2003 Tokachi-oki earthquake(Honda et al. 2004)

-  Estimated total slip distribution

## Reflection surveys

- Refraction surveys

- K-NET・KiK-net

- Microtremor surveys

- Distribution of data for modeling underground structure

## Subsurface structure in Hokkaido Area

- Vs=700m/s

- Vs=1100m/s

- Vs=1700m/s

- Vs=2200m/s

- Vs=3200m/s

**Subsurface structure in Hokkaido Area**

## Numerical simulation

- Velocity waveforms[cm/s]: Filter 5-25s

## Slide 28

## Hybrid simulation (FDM+SGM) using characterized source model

## Comparison of Peak Ground Velocities 

**Comparison of Peak Ground Velocities**

## Publication system for seismic hazard maps

## Seismic Hazard Station

**Seismic Fragility**

**Seismic Risk**
** ****Assessment**

**Seismic Risk **
**Management**

**Strong-motion Monitoring**

**Integrated **
**Geological **
**Information **
**System**

**Strong-motion simulator**

- +

- +

**       ****Seismic Hazard Station**

**Probabilistic**

-     **Scenario**

**University**
**Research**

**Local **
**government**
**Hazard **
**Assessment**

**Seismic Hazard Station**

**Publication**