An experimental investigation of dyke injection under regional extensional stress

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https://hal.archives-ouvertes.fr/hal-01146228

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An experimental investigation of dyke injection under

regional extensional stress

Katherine A. Daniels, Thierry Menand

To cite this version:

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∆

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∞

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z

z = x + iy

Z

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s

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s

σ

s

σ

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γ

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-

σ

y

/P

I

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σ σ

σ

ε

x

ε

y

x

y

σ σ

σ

x y

z

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σ

U

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N

Silsa Extension direction

D

30o -30o 0o 0o ₃₀o

A

Red Sea Gulf of Aden Somalia Yemen Afar Eritrea Sudan Addis Ababa ETHIOPIA

Main Ethiopian Rift

Djibouti

B

Recent Dykes Dabbahu Gabho Ado ‘Ale Volcanic Complex Semara 0 500 1000 1500 2000 Elevation (m) Silsa

N

C

20 10 0 10 20 30 40 50 60 70 1981 1980 1979 1978 1977 1982 1983 1984 1976 1975 2013 2012 2011 2010 2009 2008 2007 2006 80 2005 1 2 3 4

Afar rifting episode 2005-2009

Krafla rifting episode 1975-1984

Distance along rift segment (km)

Year

E

B C

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Gelatine block

Layer 2 = 10 L

Layer 1 = 29 L

Injections

TANK 1

Injections

TANK 1

C)

A)

Gelatine block

Layer 2 = 10 L

TANK 1

Layer 1 = 29 L

Injections

Metal heating plate

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A)

B)

C)

D)

Plan-view

Side-view

Injection 1

20 cm

_{20 cm}

Propagation direction of

later dyke changes once

tip of later dyke has past

the end of the first dyke.

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0

1

2

3

4

5

6

7

8

9

10

0

10

20

30

40

50

60

70

80 Injection Spacing (cm)

Rotation Angle (degrees)

Extension = 0.01 m

Extension = 0.02 m

Extension = 0.03 m

First Injections

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-1 -1 -0. 8 -0.8 -0.6-0.4 -0.6 -0.₄ -0.2 _-0.2 -0.2 -0.2 0 0 0 0 0 0 0. 2 0.2 0.2 0.2 0. 4 0.4 0.4 0.6 0.6 0.8 0.8

1

2

3

0 -3

-2

-1

1

2

3 Dir

ec

tion nor

mal t

o the dyke (y)

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x

y

x

Displacement of the solid

Maximum aperture

A)

B)

spatial evolution of the normal stress

spatial evolution of the approxi-mation of the normal stress

residual

Unit distance away from crack opening

Normalised normal stress

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0

1

2

0

0.5

1

1.5

2

2.5

0

10

20

30

40

50

60

70

80

90 Normalised Remote Tensile Stress (

y

/

P

I

)

Normalised

Injection

Spacing

(ds / h)

Rotation Angle

A)

B)

3

5

7

9

11

13

15

17

19

21

23

0

10

20

30

40

50 Experiment Number

Difference between

Measured and Pre

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