Multi-Point Measurement System and Data Processing

for Earthquakes Monitoring

Valery Korepanov and Fedir Dudkin

Lviv Center of Institute for Space Research, 5-A Naukova str,. 79060 Lviv, Ukraine

Keywords: Earthquake, Magnetic Precursors, Data Processing.

Abstract: Lithospheric ultra low frequency (ULF) magnetic activity is recently considered as very promising

candidate for application to short-time earthquake (EQ) forecasting. However the intensity of the ULF

lithospheric magnetic field is very weak and often masked by much stronger ionospheric and

magnetospheric signals. The study of pre-EQ magnetic activity before the occurrence of strong EQ is a very

hard problem which consists of the identification and localization of weak signal sources in EQ-hazardous

areas of the Earth’s crust. A new approach is developed to find a source of pre-EQ ULF electromagnetic

activity of lithospheric origin. For separation and localization of such sources a new polarization ellipse

technique has been used to process data acquired from 3-component magnetometers. The polarization

ellipse is formed by the magnetic field components at the measurement station. Calculations based on

polarization ellipse parameters from two distant points allow discrimination of seismo-EM signals from

natural background ULF signals. The results of experimental verification of this method in Kanto region

(Japan), known as one of the most seismoactive, are given which partially confirm its efficiency and give

hope, with its further improvement, to the progress in the EQ precursors reliable detection in other regions

of the Globe, particularly, in Iceland known by the active seismic activity.

1 INTRODUCTION

Short-term earthquake (EQ) prediction, despite

intensive efforts in last half a century, still remains

unattainable though numbers of promising leads and

directions are indicated (see Uyeda et al., 2009);

(Dudkin et al., 2010) for recent review on the

subject). The anomalous electromagnetic (EM)

emission in ultra low frequency (ULF) band (0.001-

10 Hz), believed to be emanating from within the

focal zones, have emerged as potential precursor

candidates for short-term EQ prediction (Hattori and

Hayakawa, 2007); (Hayakawa et al., 1996; 2000;

2007); (Molchanov and Hayakawa, 1995);

(Molchanov et al., 1992; 2004). This observational

conviction is further reinforced from the suggestions

that mechanical deformations or microfracturing in

the impending focal zones may give rise to pre-

and/or co-seismic EM emission in ULF band due to

one or more of the following factors: (1) movement

of conductive medium in the Earth’s permanent

magnetic field (inductive effect) (Fedorov et al.,

2001); (Surkov et al., 2003); (2) displacements of

boundaries between high and low conductive crustal

blocks (Dudkin et al., 2003); (3) electrokinetic effect

(Mizutani et al., 1976); (Fitterman, 1979); (4)

piezoelectric or piezomagnetic effects (Martin et al,

1978); (Ogawa et al., 1985); (Johnston et al., 1994);

(Ogawa and Utada, 2000) and (5) microfracture

electrification (Molchanov and Hayakawa, 1995).

(All references are given as example). The ULF EM

field attenuate rather weakly in crustal material and

hence, according to theoretical consideration,

associated magnetic field can be detected at large

distances up to 100-150 km (Hayakawa et al., 2007).

The practical detection and application of

precursory EM signals for real time EQ prediction

continue to be challenging due to several problems:

(i) intensity of anticipated seismo-EM signals in

ULF band is very low (with a few exceptions, e.g.,

(Fraser-Smith et al., 1990); (Bleier et al., 2009),

where magnetometers happened to be in the close

proximity to epicenter, critics see in (Campbell,

2009); (Thomas et al., 2009), (ii) difficulty of

discrimination of weak seismo-EM signals from the

background natural EM fields of ionospheric and

magnetospheric origin and (iii) finally the precision

limitation of the localization of precursor source or,

at least, determination of azimuth direction to the

source zone. Very often these problems are

119

Korepanov V. and Dudkin F..

Multi-Point Measurement System and Data Processing for Earthquakes Monitoring.

DOI: 10.5220/0004506201190124

In Proceedings of the 10th International Conference on Signal Processing and Multimedia Applications and 10th International Conference on Wireless

Information Networks and Systems (SIGMAP-2013), pages 119-124

ISBN: 978-989-8565-74-7

 2013 SCITEPRESS (Science and Technology Publications, Lda.)

aggravated by short time (less than 5 minutes) of

precursor existence (Bleier et al., 2009). With the

availability of very sensitive induction type 3-

component magnetometers with high suppression of

man-made interference (Pronenko, 2010), the

recording of high quality magnetic data in ULF

bands has greatly improved (Hayakawa et al., 2007).

For the second problem, polarization analysis

incorporating the ratio S

and S

are the

spectral intensities of vertical and horizontal

magnetic field components)

is found effective, at

least partially, in distinguishing seismo-EM signals

from geomagnetic field fluctuations (Hayakawa et

al., 1996). The formulations of principal component

analysis and fractal approach have been used with

some success in discriminating the signals of extra-

terrestrial and seismotectonic origin in magnetic

field records (see, for example, Hayakawa et al.,

1999; 2007); (Serita et al., 2005); Ida and

Hayakawa, 2006). With the aim of the identification

of source location, the phase difference as well as

amplitude difference techniques between pair or

more observation points, so-called gradiometric

method, was advanced (Ismaguilov et al., 2003;

Surkov et al., 2004). However a space derivative of

magnetic field is very unstable at low signal-to-noise

(S/N) ratio and may give a big error in the

estimation of source direction (see remarks about

S/N ratio in [Dudkin et al., 2003]). Very promising

in the seismo-EM precursors direction finding

problem solution is an application of the polarization

ellipse (PE) technique, where the PE major axis

behavior is investigated (goniometric method) (Du

et al., 2002; Schekotov et al., 2007, 2008). This

technique allows determination of trends in azimuth

angle of anomalous ULF signal and possibly area of

EQ epicentre. Taking into account that ULF

magnetic source is always in the PE plane the new

method of magnetic precursor source location when

at least two observation points are available has been

proposed by present authors (Dudkin et al., 2010;

2011). In the present paper expanding the steps of

this new direction-finding approach, we use the

information on magnetic field data from two stations

operated simultaneously in Kanto seismoactive

region of Japan. The organization of observation site

at Iceland to check the method is further proposed.

2 EXPERIMENT, RESULTS AND

DISCUSSION

To test the PE method efficiency for locating source

region of EM fields produced during EQ preparation

process, the same methodology as described in

(Dudkin et al, 2010, 2011) was applied to the

magnetic data recorded in 2005 in Kanto region,

Japan (Figure 1). The Kanto region is heavily

populated and EQs can happen close to urban areas.

This region is one of the most seismoactive in Japan.

Figure 1: The map of Kanto region.

Seismic activity there occurs due to movement of

Pacific and Philippine Sea plates. The plate

boundaries underneath the Kanto region are just 10-

40 km below the surface of the Earth and have a

complex structure. EQs can occur there both due to

subducting plates and due to active faults in land.

One-year data in frequency range 0.0001-0.5 Hz

from two fluxgate magnetometers located in

Kakioka and Kanozan geomagnetic observatories

(Figure 2) were analyzed.

Figure 2: Map of Kakioka-Kanozan area.

The peculiarity of these data is very high man-

made electromagnetic interference which

complicates much the detection of seismogenic

signals.

The monitored area 90x90x90 km was decomposed

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into 5832 subblocks with dimensions 5x5x5 km,

total volume about 730,000km

(Figure 3). The data

about seismicity in monitored area during the year

2005 were obtained from USGS catalogue. Five EQs

with magnitude M

5.0 and above occurred there

during the year 2005 with depths range from 40 to

61 km.

Figure 3: Decomposition of the monitored area.

At the lithospheric magnetic activity detection

the same procedure of “blind search”, as for data

obtained in China (Dudkin et al, 2011) has been

used. The distribution of number of M-lines in time,

which are believed to indicate to the magnetic

anomalies source (Dudkin et al, 2010) in depth range

0-90 km over the year 2005 and of the signals

classified as ionospheric at the background of Kp-

index value, is shown in Figure 4.

Figure 4: Time distribution of M-lines (red) ionospheric

signals (blue) and Kp index (black) numbers in depth

range 0-90 km over the year 2005.

We may see that the number of the

ionospheric/magnetospheric signals (blue) is in good

correlation with diurnal value index of global

geomagnetic activity Kp (black). Cross-correlation

function of Kp-index value with lithospheric and

ionospheric signals at two thresholds (50 pT and 150

pT) is shown in Figure 5 a,b.

We can see very high correlation of

ionospheric/magnetospheric M-lines number with

Kp-index value almost independently of minimal

signal threshold, unlike the lithospheric M-lines. At

decreasing of signal threshold the method selectivity

also decays, which leads to increasing of correlation

between lithospheric M-lines number and Kp-index

value.

Figure 5: Cross-correlation function of Kp-index value

with lithospheric and ionospheric signals at thresholds 50

pT and 150 pT for minor axis of magnetic field

polarization ellipse.

The increased lithospheric activity was found

only for 3 EQs from 5 under study : 1) on 7 April, 3

days before EQ M

5.9; 2) on July, 17 and 21, 6 and

2 days respectively before EQ M

5.9; 3) on

August, 29, 48 days before EQ M

5.0. The depth

distribution of blocks with magnetic activity in depth

range 52.5-82.5 km on July, 17 and in depth range

17.5-47.5 km on August, 29 are shown in Figure 6

a,b.

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121

Figure 6: Depth distribution of pre-EQ lithospheric

magnetic activity a) on on July, 17 b) on August, 29. Red

circles denote EQ epicentres.

It is clearly seen that the maximal number of M-

lines crosses the slab at the same depth where the

EQ occurred, what confirms the validity of the

method. For other two cases we did not get clear

correspondence with M-lines occurrence. Several

causes of these rather poor results may be

mentioned.

1. The region is densely populated and the local

interference level was very high.

2. The observation network was very sparse and

distance between magnetometers was too big.

3. The local tectonic structure is extremely

complicated. The crustal block boundaries and

rectangular fault model for Kanto region is

shown in Fig. 7.

Red lines indicate boundaries of the crustal blocks

on the surface. Dashed rectangles indicate

rectangular faults with a solid yellow line indicating

a fault upper edge. (The block boundaries are drawn

with use of article: Nishimura et al., 2007). Red

circles denote the studied EQs. Red stars indicate the

centres of maximal pre-EQ lithospheric activity.

As it is seen at this figure, the light blue lines

show the statistically averaged azimuths for

lithospheric M-lines, which in general coincide with

direction of local seismogenic fault as for precedent

cases. This may be the partial confirmation that the

method works here also, but the observation

technology has to be improved.

Figure 7: Crustal block boundaries and rectangular fault

model. Red lines indicate boundaries of the crustal blocks

on surface. Dashed rectangles indicate rectangular faults

with a solid yellow line indicating a fault upper edge. Red

circles denote the studied EQs. Red stars indicate the

centres of maximal pre-EQ lithospheric activity. Light

blue lines show the statistically averaged azimuths for

lithospheric M-lines.

Very interesting region for EQ magnetic

precursor study is Iceland. It is the part of the Mid-

Atlantic Ridge which marks the division between the

Eurasian and North American tectonic plates, Figure

There the seismic activity near Iceland during

years 2010-2013 is shown, where minor white

circles denote the epicenters of EQ with M4.0 - 4.9

and major ones – M5.0 - 5.5. The boundary between

the tectonic plates is marked by red line. The

example of magnetometer sites location for study of

pre-EQ lithospheric magnetic activity near

Reykjavik, Iceland is marked by green

squares.

Figure 8: The seismic activity near Iceland during years

2010-2013.

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3 CONCLUSIONS

New direction-finding method for study of ULF

lithospheric magnetic activity with use of two

spaced 3-component magnetometers was tested in

seismoactive area of Kanto region (Japan). For

analysis of pre-EQ lithospheric ULF magnetic

activity there, the area 90x90x90 km was chosen

between two measuring sites Kanozan and Kakioka.

The data from their magnetometers were analysed

during the year 2005 with special attention on

magnetic precursor for five main EQs with M ≥ 5.0.

Because of Kanto region specific peculiarities

(zone of the subducting plates with deep EQ

hypocentres, high level of industrial interference and

very sparse observation network with big distance

between magnetometers) the ULF magnetic

precursors were found only for three EQ.

The pre-EQ magnetic activity was found 48-2

days before EQ in frequency range 0.0007-0.01 Hz

at depths close to focal depths of main strikes. The

M-lines orientation was well coinciding also with

the local fault direction. It is shown that controlled

by the orientation of seismogenic faults, resulting

seismo-EM field would have definite orientation in

comparison to the isotropic direction distribution of

highly variable natural signals arising from complex

ionospheric-magnetospheric interactions. Based on

these physical considerations, the interactions lines

defined by the planes of PE, formed by the magnetic

fields at minimum two sites, define the azimuth of

seismo-EM source.

It may be concluded that in order to raise the

reliability of determination of slow crustal

nucleation processes preceding EQ (which form pre-

EQ ULF lithospheric magnetic activity, i.e. magnetic

precursors), it is necessary to cover the monitored

area with magnetometer density not less than one

magnetometer per 2000 sq. km (the distance

between measuring sites less than 50 km). Already

available knowledge on the role of high pressure

fluids in generating the EQs favours electrokinetic

effect to be one of the possible source mechanisms

for seismo-EM fields there. Testing the proposed

formulation in the other active seismic belts and

preferably employing multiple stations would help

generalization of the methodology for future EQ

precursory studies.

This study is partly supported by SSAU contract

No 4-04/13.

REFERENCES

Bleier, T., Dunson, C., Maniscalco, M., Bryant, N.,

Bambery, R., Freund, F., 2009. Investigation of ULF

magnetic pulsations, air conductivity changes, and

infra red signatures associated with the 30 October

Alum Rock M5.4 earthquake, In Nat. Hazards Earth

Syst. Sci., 9, 585–603.

Campbell, W. H., 2009. Natural magnetic disturbances

fields, not precursors, preceding the Loma Prieta

earthquake. In J. Geophys. Res., 114, A05307,

doi:10.1029/2008JA013932.

Du, A., Huang, Q., Yang, S., 2002. Epicenter location by

abnormal ULF electromagnetic emissions. In

Geophys. Res. Lett., 29 (10), 1455-1458.

Dudkin, F., De Santis, A., Korepanov, V., 2003. Active

EM sounding for early warning of earthquakes and

volcanic eruptions, In Phys. Earth Planet. Inter., 139

(3, 4), 187-195.

Dudkin, F., Rawat, G., Arora, B. R., Korepanov, V.,

Leontyeva, O., and Sharma, A. K. 2010. Application

of polarization ellipse technique for analysis of ULF

magnetic fields from two distant stations in Koyna-

Warna seismoactive region, West India, In Nat.

Hazards Earth Syst. Sci., 10, 1513–1522.

Dudkin, F., Korepanov, V., Yang, D., Li, Q. and

Leontyeva, O., Analysis of the local lithospheric

magnetic activity before and after Panzhihua Mw=6.0

earthquake (30 August 2008, China), 2011. In Nat.

Hazards Earth Syst. Sci, 11, 1-10, doi: 10.5194/nhess-

11-1-2011.

Fedorov, E., Pilipenko, V., Uyeda, S., 200l. Electric and

Magnetic Fields Generated by Electrokinetic

Processes in a Conductive Crust. In Phys. Chem. Earth

(C), 26 (10-12), 793-799.

Fitterman, D. V., 1979. Theory of electrokinetic magnetic

anomalies in a faulted half-space, In J. Geophys. Res.,

84 (B11), 6031-6040.

Fraser-Smith, A. C., Bernardi, A., McGill, P. R., Ladd, M.

E., Helliwell, R. A., Villard Jr., O. G., 1990. Low-

frequency magnetic field measurements near the

epicenter of the Ms 7.1 Loma Prieta earthquake. In

Geophys. Res. Lett., 17, 1465-1468.

Hattori, K. and Hayakawa, M., 2007. Recent progress and

state of the art of seismo-electromagnetics, In IEEJ

Transactions on Fundamentals and Materials, 127(1),

4–6.

Hayakawa, M., Kawate, R., Molchanov, O. A., Yumoto,

K., 1996. Results of ultra-low-frequency magnetic

field measurements during the Guam earthquake of 8

August 1993. In Geophys. Res. Lett., 23, 241–244.

Hayakawa, M., Itoh, T., Smirnova, N., 1999. Fractal

analysis of ULF geomagnetic data associated with the

Guam earthquake on 8 August 1993. In Geophys. Res.

Lett., 26, 2797–2800.

Hayakawa, M., Itoh, T., Hattori, K., Yumoto, K., 2000.

ULF electromagnetic precursors for an earthquake in

Biak, Indonesia on 17 February 1966. In Geophys.

Res. Lett., 27, 1531–1534.

Multi-PointMeasurementSystemandDataProcessingforEarthquakesMonitoring

123

Hayakawa, M., Hattori, K., Ohta, K., 2007. Monitoring of

ULF (ultra-low-frequency) Geomagnetic Variations

Associated with Earthquakes. In Sensors, 7, 1108-

1122.

Ida, Y., Hayakawa, M., 2006. Fractal analysis for the ULF

data during the 1993 Guam earthquake to study

prefracture criticality. In Nonlin. Processes Geophys.,

13, 409–412.

Ismaguilov, V. S., Kopytenko, Yu. A., Hattori, K.,

Hayakawa, M., 2003. Variations of phase velocity and

gradient values of ULF geomagnetic disturbances

connected with the Izu strong earthquakes. In Nat.

Hazards Earth Syst. Sci., 3, 211–215.

Johnston, M. J. S., Muller, J. S. and Sasai, Y., 1994.

Magnetic field observations in the near field: the 28

June, 1992 Mw 7.3 Landers, California Earthquake. In

Bull Seism. Soc. Am., 84, 792-798.

Martin, R. J., Habermann, R. E., Wyss, M., 1978. The

effect of stress cycling and inelastic volumetric strain

on remanent magnetization. In J. Geophys. Res., 83,

3485-3496.

Mizutani, H., Ishido, T., Yokokura, T., Ohnishi, S., 1976.

Electrokinetic phenomena associated with

earthquakes. In Geophys. Res. Lett., 13, 365-368.

Molchanov, O. A., Kopytenko, Yu. A., Voronov, P. M.,

Kopytenko, E .A., Matiashvili, T.G., Fraser-Smith,

A.C., Bernardy, A., 1992. Results of ULF magnetic

field measurements near the epicenters of the Spitak

(Ms = 6.9) and Loma Prieta (Ms = 7.1) earthquakes:

comparative analysis. In Geophys. Res. Lett., 19,

1495-1498.

Molchanov, O. A., Hayakawa, M., 1995. Generation of

ULF electromagnetic emissions by microfracturing. In

Geohpys. Res. Lett., 22, 3091–3094.

Molchanov, O. A., Schekotov, A. Yu., Fedorov, E.,

Belyaev, G. G., Solovieva, M. S., Hayakawa, M.,

2004. Preseismic ULF effect and possible

interpretation. In Annals of Geophysics, 47 (1), 119-

131.

Nishimura, T., Sagiya, T., Stein, R., 2007. Crustal block

kinematics and seismic potential of the northernmost

Philippine Sea plate and Izu microplate, central Japan,

inferred from GPS and leveling data. In J. Geophys.

Res., 112, doi:10.1029/2005JB004102.

Ogawa, T., Oike, K., Miura, T., 1985. Electromagnetic

Radiations from Rocks. In J. Geophys. Res., 90 (D4),

6245-6249.

Ogawa, T., Utada, H., 2000. Coseismic piezoelectric

effects due to a dislocation. 1. An analytic far and

early-time field solution in a homogeneous whole

space. In Phys. Earth Planet. Inter., 121, 273–288.

Pronenko, V. A., 2010. Interference-proof induction

magnetometer for ULF band. In Proceedings of VII

International conference “Metrology-2010”, Kharkiv,

Ukraine, 237-240, (in Russian).

Schekotov, A. Y., Molchanov, O. A., Hayakawa, M.,

Fedorov, E. N., Chebrov, V. N., Sinitsin, V. I.,

Gordeev, E. E., Belyaev, G. G., Yagova, N. V., 2007.

ULF/ELF magnetic field variations from atmosphere

induced by seismicity. In Radio Sci., 42, RS6S90,

doi:10.1029/2005RS003441.

Schekotov, A. Y., Molchanov, O. A., Hayakawa, M.,

Fedorov, E. N., Chebrov, V. N., Sinitsin, V. I.,

Gordeev, E. E., Andreevsky, S. E., Belyaev, G. G.,

Yagova, N. V., Gladishev, V. A., Baransky, L. N.,

2008. About possibility to locate an EQ epicenter

using parameters of ELF/ULF preseismic emission. In

Nat. Hazards Earth Syst. Sci., 8, 1237–1242.

Serita, A., Hattori, K., Yoshino, C., Hayakawa, M.,

Isezaki, N., 2005. Principal component analysis and

singular spectrum analysis of ULF geomagnetic data

associated with earthquakes. In Nat. Hazards Earth

Syst. Sci., 5, 685–689.

Surkov, V. V., Molchanov, O. A., Hayakawa, M., 2003.

Pre-earthquake ULF electromagnetic perturbations as

a result of inductive seismomagnetic phenomena

during microfracturing. In J. Atmos. Sol. Terr. Phys.,

65 (1), 31-46.

Surkov, V. V., Molchanov, O. A., Hayakawa, M., 2004. A

direction finding technique for the ULF

electromagnetic source. In Nat. Hazards Earth Syst.

Sci., 4, 513–517.

Thomas, J. N., Love, J. J., Johnston, M. J. S., and

Kiyohumi, Y., 2009. On the reported magnetic

precursor of the 1993 Guam earthquake. In Geophys.

Res. Lett., 36, L16301, doi:10.1029/2009GL039020.

Uyeda, S., Nagao, T., Kamogava, M., 2009. Short-term

earthquake prediction: Current status of seismo-

electromagnetics. In Tectonophysics, 470, 205-213.

SIGMAP2013-InternationalConferenceonSignalProcessingandMultimediaApplications

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