Physics of Seismo-electromagnetic Phenomena

(1)

Physics of

Seismo-electromagnetic Phenomena

H.G. Silva

1 _{and M. Bezzeghoud}

1,2

1 _{Geophysics Centre of Évora, University of Évora, Portugal}

2 _{Department of Physics, University of Évora, Portugal}

(2)

Outline

ò

 

Seismic Precursors

ò

 

Seismo-Electromagnetic Phenomena (SEM)

ò

 

Field Observations

ò

 

Project

ò

 

Atmospheric Electric Field (Sousel EQ)

ò

 

Laboratorial Experiments

ò

 

Electric Transport in Granitic Rocks

ò

 

Theoretical Model

ò

 

Piezoelectric Effect During Crack Propagation

(3)

Seismic precursors

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

3

Nat. Hazards Earth Syst. Sci., 9, 1221–1226, 2009 www.nat-hazards-earth-syst-sci.net/9/1221/2009/ © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License.

Natural Hazards

and Earth

System Sciences

Specific variations of the atmospheric electric field potential

gradient as a possible precursor of Caucasus earthquakes

N. Kachakhidze1_{, M. Kachakhidze}1_{, Z. Kereselidze}2_{, and G. Ramishvili}3 1_{Tbilisi State University, 3, I. Chavchavadze av., 0128, Tbilisi, Georgia} 2_{Nodia Institute of Geophysics, 1, Alexidze str., 0183, Tbilisi, Georgia}

3_{I. Chavchavadze University, National Astrophysical Observatory, 2, Kazbegi av., 0160, Tbilisi, Georgia}

Received: 20 October 2008 – Revised: 12 June 2009 – Accepted: 12 June 2009 – Published: 22 July 2009

Abstract. The subject of the research is the study of

anoma-lous disturbances of the gradient of electric field potential of the atmosphere as possible precursors of earthquakes.

In order to reveal such precursor Dusheti observatory (ϕ=42.05; λ=44.42) records of electric field potential’s gra-dient (EFPG) of the atmosphere are considered for 41 earth-quakes (M≥5.0) occurrence moments in the Caucasus re-gion.

Seasonal variations of atmospheric electric field potential gradient and inter overlapping influence of meteorological parameters upon this parameter are studied. Original method of “filtration” is devised and used in order to identify the ef-fect of EFPG “clear” anomalies.

The so-called “clear” anomalies are revealed from (−148.9 V/m) to 188.5 V/m limits and they are connected with occurrence moments of 29 earthquakes out of 41 dis-cussed earthquakes (about 71%). “clear” anomalies manifest themselves in 11-day precursor window.

Duration of anomalies is from 40 to 90 min.

1 Introduction

When earthquake problems are investigated it should be taken into consideration that enough knowledge and infor-mation about the process of earthquake preparation are not available yet. So we have to use indirect method, it means, to observe all those phenomena which accompany com-plex process of earthquake preparation in the seismosphere.

Correspondence to: N. Kachakhidze

(ninokachakhidze@rambler.ru)

Earthquake preparation on the Earth’s surface is mainly ex-pressed by anomalous changes of various geophysical fields, though earthquake precursors do not always manifest them-selves due to peculiarities of geophysical structure of source area and complex geophysical processes which take place in the source (Park et al., 1993; Plotkin, 2003; Pulinet, 2005; Prasad et al., 2000; Pulinets et al., 2006; Ouzounov et al., 2007).

We consider investigation of atmospheric electric precur-sor as important stage of earthquake problem.

Many scientific articles have considered anomalous dis-turbances of characteristic parameters of atmospheric elec-tric field in earthquake preparation period. In many works near-ground atmospheric layer is considered as “transmis-sion” layer between the Earth and the ionosphere (Gufeld et al., 1988; Molchanov et al., 1993, 1998, 2001; Hayakawa et al., 2000; Kachakhidze, 2000; Smirnov, 2008).

Amplitudes of EFPG disturbances are several times larger that average value of this parameter. It is obvious that deter-mination of EFPG precursor time is problematic task (Liper-ovsky et al., 2008; Triantis et al., 2008).

Examination of contemporary investigations enables us to note that perfect theoretical model of such important phe-nomenon as atmospheric electric precursor of an earthquake, is not yet constructed.

2 Data

Our aim is to investigate “seismic share” in anomalous dis-turbances of atmospheric electric field.

We have considered change of EFPG near-ground layer of the atmosphere some days before earthquake occurrence. Published by Copernicus Publications on behalf of the European Geosciences Union.

Nat. Hazards Earth Syst. Sci., 9, 1221–1226, 2009 www.nat-hazards-earth-syst-sci.net/9/1221/2009/ © Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License.

Natural Hazards

and Earth

System Sciences

Specific variations of the atmospheric electric field potential

gradient as a possible precursor of Caucasus earthquakes

N. Kachakhidze1_{, M. Kachakhidze}1_{, Z. Kereselidze}2_{, and G. Ramishvili}3 1_{Tbilisi State University, 3, I. Chavchavadze av., 0128, Tbilisi, Georgia} 2_{Nodia Institute of Geophysics, 1, Alexidze str., 0183, Tbilisi, Georgia}

3_{I. Chavchavadze University, National Astrophysical Observatory, 2, Kazbegi av., 0160, Tbilisi, Georgia}

Received: 20 October 2008 – Revised: 12 June 2009 – Accepted: 12 June 2009 – Published: 22 July 2009

Abstract. The subject of the research is the study of

anoma-lous disturbances of the gradient of electric field potential of the atmosphere as possible precursors of earthquakes.

In order to reveal such precursor Dusheti observatory (ϕ=42.05; λ=44.42) records of electric field potential’s gra-dient (EFPG) of the atmosphere are considered for 41

earth-quakes (M≥5.0) occurrence moments in the Caucasus

re-gion.

Seasonal variations of atmospheric electric field potential gradient and inter overlapping influence of meteorological parameters upon this parameter are studied. Original method of “filtration” is devised and used in order to identify the ef-fect of EFPG “clear” anomalies.

The so-called “clear” anomalies are revealed from

(−148.9 V/m) to 188.5 V/m limits and they are connected

with occurrence moments of 29 earthquakes out of 41 dis-cussed earthquakes (about 71%). “clear” anomalies manifest themselves in 11-day precursor window.

Duration of anomalies is from 40 to 90 min.

1 Introduction

When earthquake problems are investigated it should be taken into consideration that enough knowledge and infor-mation about the process of earthquake preparation are not available yet. So we have to use indirect method, it means, to observe all those phenomena which accompany com-plex process of earthquake preparation in the seismosphere.

Correspondence to: N. Kachakhidze

(ninokachakhidze@rambler.ru)

Earthquake preparation on the Earth’s surface is mainly ex-pressed by anomalous changes of various geophysical fields, though earthquake precursors do not always manifest them-selves due to peculiarities of geophysical structure of source area and complex geophysical processes which take place in the source (Park et al., 1993; Plotkin, 2003; Pulinet, 2005; Prasad et al., 2000; Pulinets et al., 2006; Ouzounov et al., 2007).

We consider investigation of atmospheric electric precur-sor as important stage of earthquake problem.

Many scientific articles have considered anomalous dis-turbances of characteristic parameters of atmospheric elec-tric field in earthquake preparation period. In many works near-ground atmospheric layer is considered as “transmis-sion” layer between the Earth and the ionosphere (Gufeld et al., 1988; Molchanov et al., 1993, 1998, 2001; Hayakawa et al., 2000; Kachakhidze, 2000; Smirnov, 2008).

Amplitudes of EFPG disturbances are several times larger that average value of this parameter. It is obvious that deter-mination of EFPG precursor time is problematic task (Liper-ovsky et al., 2008; Triantis et al., 2008).

Examination of contemporary investigations enables us to note that perfect theoretical model of such important phe-nomenon as atmospheric electric precursor of an earthquake, is not yet constructed.

2 Data

Our aim is to investigate “seismic share” in anomalous dis-turbances of atmospheric electric field.

We have considered change of EFPG near-ground layer of the atmosphere some days before earthquake occurrence. Published by Copernicus Publications on behalf of the European Geosciences Union.

(4)

SEM Phenomena

ò

 

Anomalous electrical

signals

ò

 

Abnormal ultra-low

frequency EM emissions

ò

 

Anomalies in very-low

and low frequency radio

transmissions

ò

 

Variation of the total

electron content (TEC)

in the ionosphere

(5)

Field Observations

C. Serrano, A.H. Reis, R.N. Rosa, J.F. Borges, B. Caldeira e M.

Tlemçani, A. Araújo, and P.F. Biagi*

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

5 with

(6)

Project

Atmospheric Electric

Field Sensor

Radio Receiver for

VLF/LF signals

Atmospheric Radon Meter

(installation)

Magnetometers for ultra-low

frequencies (planned)

(7)

Sousel Earthquake

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

7 The EQ occurred March 27, 2010 in

Sousel (Alentejo) with a depth of 15 km

and magnitude of M

_L

= 4.1 (IM).

The electric field sensor was placed ~52

km from the EQ epicentre and within its

preparation zone.

Earthquake

preparation radius

(8)

Atmospheric electric field

The electric field sensor is a

JCI 131 installed at the

University of Évora. This

equipment is in operation

since February 2005 to date.

Usual atmospheric electric field.

In this study we concentrate on

the period from January 2007

until December 2010.

(9)

Atmospheric electric field

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

9 No human disturbance or

malfunction of the equipment

was found

The weather

conditions fit nearly

fair-weather

Atmospheric electric field: the EQ is marked

with a red star.

Weather conditions during the earthquake: the

blue lines indicate the duration of the decrease of

atmospheric electric field.

(10)

Atmospheric electric field

For this event no significant

seismic activity occurred in the

region

The weather conditions were

similar to the

Sousel earthquake

Atmospheric electric field: in which there was a

decrease in the atmospheric electric field

(11)

Atmospheric electric field

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

11

11 Rn

Rn

α

+

-

J

_c

=

σ

E

Ionosphere

Surface layer

Lower atmosphere

Lithosphere

Permeable soil

(12)

AEF: sum-up

ò

 

This study provides the first clear evidence of a significant

reduction of the vertical component of atmospheric electric

field in the preparatory phase of a seismic event.

ò

 

These observations support the idea that the radon

emanations are the mechanism behind this decrease.

ò

 

Additional work is needed to confirm this hypothesis, in

particular, the systematic measurement of radon levels is

essential.

ò

 

The installation of new atmospheric electric field sensors,

magnetometers, and radon detectors in seismic regions

(evaluation of multiple parameters) is another step in the

project.

(13)

Laboratorial Experiments

M.P.F. Graça, J. H. Monteiro, R.N. Rosa, S. K. Mendiratta*, M.

Tlemçani, P. Moita

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

13 with

(14)

Impedance spectroscopy

YC is a porphiritic coarse grained

biotitic-muscovitic granite,

y e l l o w c o l o u r e d a n d

characterized by an abundance

of large feldspar usually showing

poorly defined shapes.

YC

GM

RM

GM is a granodiorite grey

coloured and medium grained

r o c k w i t h h o m o g e n e o u s

appearance. Dark minerals is

mainly biotite.

R M i s a g r a n i t e w i t h a

homogeneous medium grained

matrix (occasionally coarser

grained quartz) and light rosy

coloured determined by the

tonality of the feldspar crystals

that stand out from a greyish

matrix.

(15)

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

15 biotite

muscovite

plagioclase

quartz

Alkaline

feldspar

biotite

quartz

plagioclase

Alkaline

feldspar

biotite

plagioclase

quartz

(16)

Impedance spectroscopy

Circular samples with approximately 24

m m d i a m e t e r a n d 2 - 4 m m i n

thicknesses were prepared. Once cut

and carefully polished (with a 15 µm

polishing disc) the samples here heated

from room-temperature (RT) up to

~400 K and after cooled down again.

Circular electrodes with a diameter of 20 mm were then established

using silver conductive paint (in the future, new contacts will be

tested). The samples were submitted again to a heat treatment at ~400

K to evaporate the silver paint solvent.

(17)

Impedance spectroscopy

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

17 Impedance spectroscopy was done with

V

_AC

= 1 V test signal in the frequency

range of 40 Hz to 1 MHz at stabilized

temperatures ranging from 100 K to 360

K. It was used an Agilent 4294A

Precision Impedance Analyzer.

N

₂

He

Vacuum

Sample

( )

[

( )

]

( )

ω

φ

ε

ω

Z

A

d

K

sin

0

0 =

ʹ′

=

ʹ′

( )

[

( )

]

( )

ω

φ

ε

ω

Z

A

d

K

cos

0

0 =

ʹ′ʹ′

=

ʹ′ʹ′

( )

ω

ε

( )

ω

ε

( )

ω

ε

∗

₌

ʹ′

₊

i

ʹ′ʹ′

(18)

Impedance spectroscopy

Impedance spectra at different temperatures: a) Real part of the dielectric constant; b) Imaginary part of the dielectric constant.

(19)

Impedance spectroscopy

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

19 Impedance spectra at different temperatures: a) Real part of the dielectric constant; b) Imaginary part of the dielectric constant.

Real and Imaginary part of

ε

as a function of temperature: a)

f

= 100 Hz; b)

f

= 1027 Hz; c)

f

= 10 520 Hz; d) comparison.

(20)

Impedance spectroscopy

Impedance spectra at different temperatures: a) Real part of the dielectric constant; b) Imaginary part of the dielectric constant.

(21)

IS: sum-up

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

21 ò

 

An anomaly in the dielectric behaviour near

T

~ 220 K is

found.

ò

 

This temperature is typical of the super-cooled phase

transition of strongly confined water affecting electronic

devises.

ò

 

Samples

YC

and

RM

show a relaxation process taking place

at f ~ 10

3 _{Hz readily evidenced in the K˝ curves here a}

significant peak appears at this frequency that does not

change with temperature.

ò

 

Our final objective is to Investigate possible mechanisms of

charge creation in different crust materials and conditions

(pressure and temperature).

(22)

Theoretical Model

Pedro M. Areias, José E. Garção, Nicolas Van Goethem

§

with

*Physics Department, University of Évora, Portugal

(23)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

23 Cauchy equation of motion and Cauchy lemma

Mass conservation

∇ · σ = ρ

D ˙u

Dt

n

T

σ = t

∂(Jρ)

∂t

= 0

with

J = det F

(24)

Piezoelectric effect

With boundary conditions

n

_{· [[b]] = 0}

n

_{· [[d]] = 0}

n

_{× [[h − v × d]] = 0}

n

_{× [[e + v × b]] = 0}

∇ × e + ˙b = 0

∇ × h + ˙d = 0

∇ · b = 0

∇ · d = 0

Ω

Γ

Material

Vacuum

Maxwell’s equations for insulators

ρ

_free

_{= 0 and j}

_free

₌

₀

_.

(25)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

25 ε =

1

2 (b

− I)

Ogdon model, N=2

(Mooney-Rivlin material)

Total Helmoltz free energy

Derived to generate the correct expression for the Maxwell stress tensor

ψ(ε, d, h) =

1

2 (1

− D) ε

T

_:

C : ε +

1 ₂

µh

T

(I + 2ε)h +

1 2�

d

T

(I + 2ε)d

₋

1

2 �

1 �

d

· d + µh · h

�

tr[ε] + d

_{· (I : ε)}

Strain tensor

Deformation

energy

Electromagnetic

terms

Piezoelectric

_effect

(26)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

26 The following loading/unloading conditions

The corresponding damage loading function

ϕ(ε) = (1

_{− D)ε}

₁

_{− ε}

_max

ϕ(ε)

_{≤ 0}

˙

Dϕ(ε) = 0

˙

D

_{≥ 0}

τ =

∂ψ

∂ε

e =

∂ψ

∂d

∂ψ

τ =

∂ψ

∂ε

e =

∂ψ

∂d

b =

∂ψ

∂h

τ =

∂ψ

∂ε

e =

∂ψ

∂d

b =

∂ψ

∂h

(27)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

27 The first variation of

τ

,

e

and

b

with respect to

ε

,

d

and

h

The third derivatives with respect

ε

_,

_d

_and

_h

_{are also needed for}

_b

δτ =

∂

2 _ψ

∂ε

2 : δε +

∂

2 ψ

∂ε∂d

· δd +

∂

2 ψ

∂ε∂h

· δh

δe =

∂

2 _ψ

∂d∂ε

: δε +

∂

2 ψ

∂d

2 · δd +

∂

2 ψ

∂d∂h

· δh

δb =

∂

2 _ψ

∂h∂ε

: δε +

∂

2 ψ

∂h∂d

· δd +

∂

2 ψ

∂h

2 · δh

(28)

Piezoelectric effect

Integrating in Ω provides the virtual work

The second variation of W is also required for the application of Newton's method.

The backward-Euler method is used for the integration

˙b ∼

=

b

n+1

− b

n

∆t

˙d ∼

=

d

n+1

− d

n

∆t

δW =

�

Ω

0

τ :

_{∇δu dΩ}

0 +

�

Ω

0

˙b · δh dΩ

0 −

�

Ω

0

(

_{∇ × δh) · e dΩ}

0 +

�

Ω

0

�

∇ × h − ˙d

�

· δd dΩ

0 +

r

b

�

Ω

0

∇ · b∇ · δbdΩ

0 + r

d

�

Ω

0

∇ · d∇ · δddΩ

0 +

�

Γ

δλ

I

_b

n

_{· [[b]]dΓ +}

�

Γ

δλ

I

_d

n

_{· [[d]]dΓ+}

�

Γ

δλ

II

_d

n

_{× [[h − v × d]]dΓ +}

�

Γ

δλ

II

_b

n

_{× [[e + v × b]]dΓ −}

�

Γ

t

_{· δudΓ}

t

+

�

Γ

e

_{× δh dΓ = 0}

(29)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

29 We use AceGen for the derivation of the discretized equations

The 2D discretization is based on a 3-node triangle

The δ-variation of (

Δ



)

δ

_{∇ (•) = ∇δ (•) − ∇ (•) ∇δu}

The d-variation of (

Δ



)

d

_{∇ (•) = ∇d (•) − ∇ (•) ∇du}

Here



is a tensor and

is a spatial gradient

Δ

u =

�

N

_K

u

_K

d =

�

N

_K

d

_K

(30)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

30

-5.475e+07 1.820e+08 4.188e+08 6.556e+08 8.924e+08 E[X] -4.387e+08 -2.243e+08 -9.914e+06 2.045e+08 4.189e+08 E[Y] -7.626e+07 -3.808e+07 8.790e+04 3.826e+07 7.643e+07 BZ

-7.862e+07

-4.230e+07

-5.978e+06

3.034e+07

6.666e+07

E[X]

-1.788e+08

-8.970e+07

-6.058e+05

8.849e+07

1.776e+08

E[Y]

-4.278e-02

-2.137e-02

5.234e-05

2.147e-02

4.289e-02

BZ

10 1 0.1 0.01 0.001 0.0001 1eï05 1eï06 1eï07

0. 4m

˙u = 1 ms

−1

I

23 = 12.71 Cm

−2

I

12 =

−5.207 Cm

−2

I

11 = 15.08 Cm

−2

! = 6

_{× 10}

−9

Fm

−1

µ = 1.256

_{× 10}

−6

Hm

−1

ν = 0.357

E = 69.59 GPa

Imposed displacement

Imposed d

xx

1 m

∆t = 1

_{× 10}

−6

_{s (each step 1% elongation)}

∆t = 1

_{× 10}

−5

_{s (each step 10% elongation)}

∆t = 1

× 10

−4

_{s (each step 100% elongation)}

Error

Original geometry

NC

−1

NC

−1

T

-5.475e+07 1.820e+08 4.188e+08 6.556e+08 8.924e+08 E[X] -4.387e+08 -2.243e+08 -9.914e+06 2.045e+08 4.189e+08 E[Y] -7.626e+07 -3.808e+07 8.790e+04 3.826e+07 7.643e+07 BZ -7.862e+07 -4.230e+07 -5.978e+06 3.034e+07 6.666e+07E[X] -1.788e+08 -8.970e+07 -6.058e+05 8.849e+07 1.776e+08E[Y] -4.278e-02 -2.137e-02 5.234e-05 2.147e-02 4.289e-02BZ 1eï08 40 30 20 10 0 10 1 0.1 0.01 0.001 0.0001 1eï05 1eï06 1eï07 50 0. 4m

˙u = 1 ms

−1

I

23

= 12.71 Cm

−2

I

12

=

−5.207 Cm

−2

I

11

= 15.08 Cm

−2

! = 6

× 10

−9

_Fm

−1

µ = 1.256

× 10

−6

_Hm

−1

ν = 0.357

E = 69.59 GPa

Imposed displacement Imposed dxx

1 m

Accumulated number of iterations ∆t = 1× 10−6s (each step 1% elongation)

∆t = 1× 10−5s (each step 10% elongation) ∆t = 1× 10−4s (each step 100% elongation)

Error Original geometry NC−1 NC−1 T -5.475e+07 1.820e+08 4.188e+08 6.556e+08 8.924e+08 E[X] -4.387e+08 -2.243e+08 -9.914e+06 2.045e+08 4.189e+08 E[Y] -7.626e+07 -3.808e+07 8.790e+04 3.826e+07 7.643e+07 BZ -7.862e+07 -4.230e+07 -5.978e+06 3.034e+07 6.666e+07E[X] -1.788e+08 -8.970e+07 -6.058e+05 8.849e+07 1.776e+08E[Y] -4.278e-02 -2.137e-02 5.234e-05 2.147e-02 4.289e-02BZ 1eï08 40 30 20 10 0 10 1 0.1 0.01 0.001 0.0001 1eï05 1eï06 1eï07 50 0. 4m

˙u = 1 ms

−1

I

23

= 12.71 Cm

−2

I

12

=

−5.207 Cm

−2

I

11

= 15.08 Cm

−2

! = 6

_{× 10}

−9

_Fm

−1

µ = 1.256

_{× 10}

−6

_Hm

−1

ν = 0.357

E = 69.59 GPa

Imposed displacement

Imposed d

xx

1 m

Error Original geometry NC−1 NC−1 T -5.475e+07 1.820e+08 4.188e+08 6.556e+08 8.924e+08 E[X] -4.387e+08 -2.243e+08 -9.914e+06 2.045e+08 4.189e+08 E[Y] -7.626e+07 -3.808e+07 8.790e+04 3.826e+07 7.643e+07 BZ -7.862e+07 -4.230e+07 -5.978e+06 3.034e+07 6.666e+07E[X] -1.788e+08 -8.970e+07 -6.058e+05 8.849e+07 1.776e+08E[Y] -4.278e-02 -2.137e-02 5.234e-05 2.147e-02 4.289e-02BZ 1eï08 40 30 20 10 0 10 1 0.1 0.01 0.001 0.0001 1eï05 1eï06 1eï07 50 0. 4m

˙u = 1 ms

−1

I

23

= 12.71 Cm

−2

I

12

=

−5.207 Cm

−2

I

11

= 15.08 Cm

−2

! = 6

× 10

−9

_Fm

−1

µ = 1.256

_{× 10}

−6

_Hm

−1

ν = 0.357

E = 69.59 GPa

Imposed displacement Imposed dxx

1 m

Error

Original geometry

NC−1

(31)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

31

(32)

Piezoelectric effect

(33)

Piezoelectric effect

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

33

(34)

Piezoelectric effect

(35)

PE: sum-up

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

35 ò

 

We were able to successfully integrate Cauchy equations of

motion and Maxwell equations within a finite strain

fracture framework

ò

 

Despite oscillations in the magnetic field, we found results

physically significant and in agreement with what is

expected

ò

 

Further verification and validation are required to firmly

pursue additions to our approach

ò

 

Revision of the boundary conditions and inclusion of

(36)

(37)

Publications

Tectónica Recente e Perigosidade Sísmica

2 de Julho de 2011

37 ò

 

Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary,

H.G. Silva

, M. Bezzeghoud,

J.P. Rocha, P.F. Biagi, M. Tlemçani, R.N. Rosa, M.A. Salgueiro da Silva, J.F. Borges, B. Caldeira, A.H. Reis, and M.

Manso, Nat. Hazards Earth Syst. Sci. 11, 241 (2011).

ò

 

The European VLF/LF radio network to search for earthquake precursors: setting up and natural/man-made disturbances, P. F.

Biagi, T. Maggipinto, F. Righetti, D. Loiacono, L. Schiavulli, T. Ligonzo, A. Ermini, I. A. Moldovan, A. S.

Moldovan, A. Buyuksarac,

H.G. Silva

, M. Bezzeghoud, and M. E. Contadakis, Nat. Hazards Earth Syst. Sci. 11,

333 (2011).

ò

 

Atmospheric electrical field anomalies associated with seismic activity,

H.G. Silva

, M. Bezzeghoud, A.H. Reis, R.N. Rosa,

M. Tlemçani, J.F. Borges, B. Caldeira, and P.F. Biagi, Nat. Hazards Earth Syst. Sci. 11, 987 (2011).

ò

 

Analysis of the LF radio signals collected in the European network during about two years

, P. F. Biagi,T. Maggipinto, F.

Righetti, L. Schiavulli, T. Ligonzo, A. Ermini, I. A. Moldovan, A. S. Moldovan, A. Buyuksarac, H.G. Silva, M.

Bezzeghoud, D.N. Arabelos, T.D. Xenos and M. E. Contadakis (submitted).

ò

 

Impedance properties of granitic rocks

, H.G. Silva, M.P.F. Graça, J. H. Monteiro, P. Moita, M. Tlemçani, R.N. Rosa,

M. Bezzeghoud, S. K. Mendiratta (in preparation).

ò

 

Influence of seismic activity in the atmospheric electrical potential gradient in Lisbon (Portugal) from 1961 until 1991

, H.G.

Silva, C. Serrano, M.M. Oliveira, M. Bezzeghoud, A.H. Reis, R.N. Rosa, and P.F. Biagi (in preparation).