what controls the timing of earthquakes n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
What controls the timing of earthquakes? 何が地震が起こるときを決めているか? PowerPoint Presentation
Download Presentation
What controls the timing of earthquakes? 何が地震が起こるときを決めているか?

Loading in 2 Seconds...

play fullscreen
1 / 38

What controls the timing of earthquakes? 何が地震が起こるときを決めているか? - PowerPoint PPT Presentation


  • 120 Views
  • Uploaded on

What controls the timing of earthquakes? 何が地震が起こるときを決めているか?.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'What controls the timing of earthquakes? 何が地震が起こるときを決めているか?' - latika


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
what controls the timing of earthquakes
What controls the timing of earthquakes?何が地震が起こるときを決めているか?
slide2

Earthquake Cycle 地震のサイクル(繰り返し) time-predictable model 時間が予測できるモデル slip-predictable model  すべり量が予測できるモデルCoulomb failure function  クーロン破壊関数Rate and State friction  速度および状態依存性摩擦Plate coupling プレートのカップリングBack-slip modeling バックスリップによるモデル Slow earthquakes  ゆっくり地震GPS

slide3

Earthquake Cycle

地震のサイクル(繰り返し)

応力

累積した

地震時すべり量

時間

slide4

Tohoku

Parkfield, California

釜石沖

slide5

Periodic Time-predicatable Slip-predicatable

  等間隔     地震の時刻が予測できる 地震のすべり量が予測できる

応力

累積した

地震時すべり量

時間

Shimazaki and Nakata, 1980

slide6

累積した地震時の隆起(m)

時間(年)

Shimazaki and Nakata, 1980

slide7

To understand (predict) occurrence of earthquakes in earthquake cycle地震の繰り返しの中で地震の起こるときを知る(予測する)には1. Stress level that earthquakes occur地震が起こる応力の値2. Current level of stress accumulation現在既に蓄積している応力の値

coulomb failure criterion navier coulomb coulomb mohr
Coulomb Failure Criterionクーロン破壊基準(Navier-Coulomb, Coulomb-Mohr)
slide10

Coulomb Fracture Criterion

クーロン破壊基準

Change of Coulomb Fracture Criterion

クーロン破壊基準の変化

slide12

Rate and State Friction Law

速度および状態依存性構成則

Dieterich, 1979, Ruina, 1983

slide14

‘a-b’

変位

a-b usually < 0

a-b > 0 → stable sliding

安定すべり

slide15

Dc

Vo

Dc

Dc

Friction Laws 摩擦則

Slip weakening すべり弱化

Rate Dependent 速度依存

Rate and State Dependent 速度および状態依存

Ohnaka 大中

coulomb
Coulombクーロン

Rate and State Friction速度および状態依存摩擦

slide17

Coulomb Criterion

クーロン基準

Rate and State

速度および状態依存

Toda et al., 2002

slide18

Global Positioning System - GPS- Measure displacement field 変位場を測定する → strain field → stress fieldひずみ場      応力場- Detect Slow Slip Events (Silent Earthquakes)ゆっくり地震(サイレンス地震)をみつける

slide20

GPS 24 satellite configuration

http://scign.jpl.nasa.gov/learn/gps1.htm

slide21

Satellite Position人工衛星の位置

  • Range領域
  • >4 Satellites → Receiver Postion
  • 4つ以上の衛星で、受信機の位置がわかる
slide22

Continuous GPS Stations

GeoNet

(GSI)

993 sta.

slide24

ひずみ速度

Dilatational Strain Rate

1996 - 2002

coupling coupling seismic slip plate rate
‘Coupling’              カップリングCoupling = seismic slip/ plate rateカップリング=地震によるすべり量/プレートの相対移動量
slide27

‘Coupling’カップリングCoupling = seismic slip/ plate rateカップリング=地震によるすべり量/プレートの相対移動量Nankai 南海 ~ 100% Tohoku 東北 ~ 60-70% Kyushu 九州 ~ 10-20% (?)

slide29

‘Back-slip’ or ‘Slip Deficit’

バックスリップ すべり欠損

Matsu-ura and

Sato, 1989

slide30

地震前

地震時

slide33

Tokai Slow Slip

東海のゆっくりすべり

2000 - present

国土地理院

slide35

Mo = μ(slip)(area)

Mw = (log(Mo) –16.1)/1.5

Slip modeling by Nagoya Univ.

slide36

What controls the timing of earthquakes?何が地震の起こるときを決めているか?- Build-up of stress (earthquake cycle)応力の蓄積(地震の繰り返し)- Level of stress depends on the plate (strain) rate and the seismic coupling応力値はプレートの(ひずみ)速度と  それが地震の発生に関与する割合(カップリング)- Earthquakes occur at some critical stress level (e.g. Coulomb failure, Rate and State) 地震はある臨界状態で起こる(例えばクーロン破壊や速度および状態依存摩擦)But, there are probably other types of triggering effectsしかし、たぶん、他の要素でも地震の発生は誘発されている

slide37

References

Dieterich, J.H., Modeling of rock friction, 1. Experimental results and constitutive equations,

J. Geophys. Res., 84, 2161-2168, 1979.

King, G.C.P., R.S. Stein, J. Lin, Static stress changes and triggering of earthquakes, Bull.

Seismol. Soc. Am., 935-953, 1994.

Matsu-ura. M. and T. Sato, Dislocation model for the earthquake cycle at convergent

Plate boundaries, Geophys. J. Int., 96, 23-32, 1989.

Ruina, A.L., Slip instability and state-variable friction laws, J. Geophys. Res., 86,

10,359-10,370, 1983.

Sagiya, T., Interplate coupling in the Tokai District, central Japan, deduced from continuous

GPS Data, Geophys. Res. Lett., 26, 2315-2318, 1999

Scholz, C.H., The mechanics of earthquakes and faulting, 2nd Edition, Cambridge Univ. Press,

2002.

Shimazaki, K. and T. Nagata, Time predictable recurrence model for large earthquakes,

Geophys. Res. Lett., 7, 279-282, 1980.

Toda, S. R. S. Stein, T. Sagiya, Evidence from the AD2000 Izu Islands earthquake swarm that

Stress rates govern seismicity, Nature, 419, 58-61, 2002.