Dr. Vladimir Dr. Vladimir FridFrid

ELECTROMAGNETIC RADIATION IS INDUCED BY FRACTURE IN BRITTLE MATERIALS

ELECTROMAGNETIC RADIATION IS INDUCED BY FRACTURE IN ELECTROMAGNETIC RADIATION IS INDUCED BY FRACTURE IN BRITTLE MATERIALSBRITTLE MATERIALS

Frequency Wavelength

100, 000 EHz 0.003 pm10,000 EHz 0.03 pm1,000 EHz 0.3 pm100 EHz 3 pm10 EHz 30 pm1 EHz 300 pm

100 PHz 3 nm10 PHz 30 nm1 PHz 300 nm

100 THz 3 µm10 THz 30 µm1 THz 300 µm

100 GHz 3 mm10 GHz 3 cm1 GHz 30 cm

100 MHz 3 m10 MHz 30 m1 MHz 300 m100 kHz 3 km10 kHz 30 km1 kHz 300 km100 Hz 3 Mm10 Hz 30 Mm1 Hz 300 Mm

γ - rays

X- rays

Ultraviolet

InfraredVisible

Short radio waveFM, TV bands

AM broadcast bandEMREMR

Long radio waves

Frid V., Rabinovitch A. and Bahat D. 2003. Fracture induced electromagnetic radiation. J. Phys. D. 36, 1620-1628Rabinovitch A., Frid V. and Bahat D. 2002. Gutenberg-Richter type relation for laboratory fracture induced electromagnetic radiation. Physical Review E 65, 011401-011404.

Stress

EMR signal

Stress

EMR signal

1) EMR amplitude increases prior to collapse

2) EMR intensity (number of EMR events per unit time) increases

Frid V., Rabinovitch A. and Bahat D. 2003. Fracture induced electromagnetic radiation. J. Phys. D. 36, 1620-1628Rabinovitch A., Frid V. and Bahat D. 1998. Parametrization of Electromagnetic radiation pulses obtained by triaxial fracture in granite samples. Phil. Mag. Lett. 5, 289 - 293.Rabinovitch A., Frid V. and Bahat D. 1999. A note on the amplitude -frequency relation of electromagnetic radiation pulses induced by material failure, Phil. Mag. Lett. 79, 195 - 200.

-0.04

-0.02

0

0.02

0.04

9.6 10-6 9.8 10-6 1 10-5 1.02 10-5 1.04 10-5 1.06 10-5pu

sle

Volta

ge, m

V

t, sec

t0 T 2π/ω

A0 - the pulse peak amplitude

T’ - the time interval to reach pulse maximum;

ω - the frequency;

ShortShort LengthyLengthy

ShortShort

LengthyLengthy

ShortShort

LengthyLengthy

3) Shape of EMR pulses changes prior to collapse;

4) The time interval to reach pulse maximum increases prior to collapse

5) The frequency of EMR pulses decreases prior to collapse

Rabinovitch A., Frid V. and Bahat D. 2002. Gutenberg-Richter type relation for laboratory fracture induced electromagnetic radiation. Physical Review E 65, 011401-011404.

6) The slope of EMR- Benioff strain release curve decreases prior to collapse;

0.0000001

0.000001

0.00001

0.0001

0.0011101001000

time to collapse event

0.0000001

0.000001

0.00001

0.0001

0.0011101001000

time to collapse event

Nucleation stage

Nucleation Nucleation stagestage

Intermediate stage

Intermediate Intermediate stagestage

Stagebefore collapse

StageStagebefore before collapsecollapse

Frid V. and K. Vozoff K. 2005. Electromagnetic radiation induced by mining rock failure. Intern. J. Coal Geology 64(1-2), 57-65

Frid V. 1998. Electromagnetic radiation method for rock and gas outburst forecast. J. Appl. Geoph. 38, 97 - 104.

Frid V. 1997. Rock-burst hazard forecast by electromagnetic radiation excited by rock fracture. J. Rock Mech. Rock Engin. 30 (4), 229-236.

Frid V. 2000. Electromagnetic radiation method water - infusion control in rockburst-prone strata, J. Appl. Geoph. 43, 5 - 13.

Frid V. 2001. Calculation of electromagnetic radiation criterion for rockbursthazard forecast in coal mines, Pure and Applied Geophysics, 158, 931-944.

2071.96

2071.98

2072

2072.02

2072.04

2072.06

2072.08

2072.1

2072.12

2072.14

2072.16

03:36:00 04:36:29 05:36:58 06:37:26 07:37:55 08:38:24 09:38:53 10:39:22 11:39:50 12:40:19 13:40:48

time

EMR

mea

n

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

Rich

ter m

egni

tude

meanRichter

EMR monitoring before roof fallEMR monitoring before roof fall

CollapsemomentCollapseCollapsemomentmoment

1) EMR amplitude increases prior to collapse

2) EMR intensity (number of EMR events per unit time) increases3) Frequency of EMR pulses decreases prior to collapse

2071.96

2071.98

2072

2072.02

2072.04

2072.06

2072.08

2072.1

2072.12

2072.14

2072.16

03:36:00 04:36:29 05:36:58 06:37:26 07:37:55 08:38:24 09:38:53 10:39:22 11:39:50 12:40:19 13:40:48

time

EMR

mea

n

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

Rich

ter m

egni

tude

meanRichter

EMR monitoring before roof fallEMR monitoring before roof fall

CollapsemomentCollapseCollapsemomentmoment

4) The slope of EMR- Benioff strain release curve decreases prior to collapse;

1000

10000

100000

1000000

1101001000

time to collapse failure, min

squa

re ro

ot o

f ene

rgy

-su

m(m

ean)

EMR induced by roof collapseEMR induced by roof collapsein minein mine

0.01

0.1

1

10

100

1000

1101001000

time to collapse event, s

A , V

EMR induced by rock EMR induced by rock compression in labcompression in lab

Six EMR indicators of an incoming collapse1) EMR amplitude increases prior to collapse

2) EMR intensity (number of EMR events per unit time) increases

3) Shape of EMR pulses changes prior to collapse;

4) The time interval to reach pulse maximum increases prior to collapse

5) The frequency of EMR pulses decreases prior to collapse

6) The slope of EMR- Benioff strain release curve decreases prior to collapse;

During the last century interest in EMR increased in connection with the problem of earthquake prognosis. Numerous investigations measured EMR anomalies prior to earthquakes and to volcanic eruptions. It was assumed that the anomalies of EMR prior to EQ were due to the formation of micro-fractures. This abnormally high EMR level occurs hours or even days before an EQ.

During the last century interest in EMR increased in connection with the problem of earthquake prognosis. Numerous investigations measured EMR anomalies prior to earthquakes and to volcanic eruptions. It was assumed that the anomalies of EMR prior to EQ were due to the formation of micro-fractures. This abnormally high EMR level occurs hours or even days before an EQ.

Parrot et al. (1993) remarked that although the existence of EMR in relation to seismic and/or volcanic activities was clear, EMR selection out of a host of artificial signals remained a significant problem.

Parrot et al. (1993) remarked that although the existence of EMR in relation to seismic and/or volcanic activities was clear, EMR selection out of a host of artificial signals remained a significant problem.

Failure stagesFailure stages

EMREMR

SeismicSeismic