Radon Precursory Anomalies for Some Earthquakes in N-W

Himalaya, India

1National Center for Research on Earthquake Engineering, Taipei, Taiwan2Department of Physics, Guru Nanak Dev University, Amritsar, India

3Department of Geosciences, National Taiwan University, Taipei, Taiwan

Vivek Walia1, Hardev Singh Virk2, Tsanyao Frank Yang3, Monika Walia3, Bikramjit Singh Bajwa2

LIST OF SOME SIGNIFICANT EARTHQUAKES IN INDIA AND ITS NEIGHBOURHOOD

6.96.9BHUJ , GUJARATBHUJ , GUJARAT70.2870.2823.4023.402001 JAN 262001 JAN 26

6.86.8CHAMOLI DIST, UPCHAMOLI DIST, UP79.4279.4230.4130.411999 MAR 291999 MAR 29

6.06.0JABALPUR,MPJABALPUR,MP80.0680.0623.0823.081997 MAY 221997 MAY 22

6.36.3LATURLATUR--OSMANABAD, MAHARASHTRAOSMANABAD, MAHARASHTRA76.6276.6218.0718.071993 SEP 301993 SEP 30

6.66.6UTTARKASHI, UP HILLSUTTARKASHI, UP HILLS78.8678.8630.7530.751991 OCT 201991 OCT 20

6.46.4BIHARBIHAR--NEPAL BORDERNEPAL BORDER86.6386.6326.7226.721988 AUG 211988 AUG 21

6.66.6MANIPURMANIPUR--MYANMAR BORDERMYANMAR BORDER95.1595.1525.1325.131988 AUG 061988 AUG 06

6.26.2KINNAUR, HPKINNAUR, HP78.4978.4932.3832.381975 JAN 191975 JAN 19

6.56.5KOYNA, MAHARASHTRAKOYNA, MAHARASHTRA73.7573.7517.3717.371967 DEC 101967 DEC 10

7.07.0ANJAR, GUJARATANJAR, GUJARAT70.070.023.323.31956 JUL 211956 JUL 21

8.58.5ARUNACHAL PRADESHARUNACHAL PRADESH--CHINA BORDERCHINA BORDER96.796.728.528.51950 AUG 151950 AUG 15

7.27.2ASSAMASSAM94.094.026.826.81943 OCT 231943 OCT 23

8.18.1ANDAMAN ISLANDSANDAMAN ISLANDS92.592.512.412.41941 JUN 261941 JUN 26

8.38.3BIHARBIHAR--NEPALBORDERNEPALBORDER86.886.826.626.61934JAN 151934JAN 15

7.17.1DHUBRI, ASSAMDHUBRI, ASSAM90.290.225.825.81930 JUL 021930 JUL 02

7.67.6SRIMANGAL, ASSAMSRIMANGAL, ASSAM91.091.024.524.51918 JUL 081918 JUL 08

8.08.0KANGRA, H.PKANGRA, H.P76.376.332.332.31905 APR 041905 APR 04

8.78.7SHILLONGPLATEAUSHILLONGPLATEAU919126261897 JUN 121897 JUN 12

7.07.0SOPOR, J&KSOPOR, J&K74.674.634.134.11885 MAY 301885 MAY 30

7.5 7.5 NEAR CACHAR, ASSAM NEAR CACHAR, ASSAM 93 93 25 25 1869 JAN 10 1869 JAN 10

8.0 8.0 KUTCH,GUJARAT KUTCH,GUJARAT 68.6 68.6 23.6 23.6 1819 JUN 16 1819 JUN 16

Long( Deg E )Long( Deg E )Lat( Deg N )Lat( Deg N )MAGNITUDEMAGNITUDELOCATIONLOCATIONEPICENTREEPICENTREDATEDATE

Chamba (1995)

Uttarkashi (1991)

Chamoli(1999)

Subsurface Soil Gases

Radon (Radon (222222Rn)Rn)

Helium (Helium (44He)He)

CarbonCarbon--didi--oxide (COoxide (CO22))

Methane (CHMethane (CH44))

• A radioactive & inert gas

• 7.5 times heavier than air

• 100 times heavier than hydrogen

• Three isotopes :

Radon (Rn222) 3.83 days

Thoron (Rn220) 54.5 sec

Actinon (Rn219) 3.92 sec

What is Radon?

What is Helium (He4)?• Generated during the radioactive decay of isotopes

of uranium and thorium in rocks and soil

• Highly diffusive and inert gas

• Shows the value 5.24 ppm in air

U238 Ra226 Rn222 Pb206 + 8 He4

Th232 Ra224 Rn220 Pb208 + 7 He4

U235 Ra223 Rn219 Pb207 + 7 He4

Factors controlling emanation

Transmission Characteristics of Bedrock

Mineralogical Effects

Uranium/Thorium Concentration

Carrier Fluids

Weather and Soil Types

• Gases measured in soils can be strongly disturbed by environmental variables like atmospheric pressure, soil temperature, rainfall, soil moisture etc.

Emanometry Technique

Radon Emanometer used for radon sampling

Soil-gas probe used for radon sampling

Soil-Gas Emanometry

Groundwater radon sampling methodolgy

Groundwater Emanometry

Correlation coefficient of radon concentration in soil-gas with different meteorological parameters at Palampur

Parameter Average(Avg)

Standard Deviation

(Std)

% Variation Coefficient(Std/Avg)

Correlation Coefficient

Radon (Bq/L) 22 12.7 58 ___

Temperature (OC) 23.9 5.4 23 0.18

Relative Humidity (%) 64.3 18.1 28 0.31

Rainfall (mm) 5.5 14.8 267 0.19

Wind Velocity (km/hr) 4.5 1.4 32 -0.27

•Radon anomaly is defined as any sudden change in radon concentration crossing the average of that season by ±2σ.

•Radon anomalies followed by seismic event is Pre-seismic

• Anomaly occur simultaneously (same day) with seismic event is called Co-seismic

• Anomaly after the seismic event is Post-seismic

Radon Anomaly

M=6.6

M=6.6

=27.55

=48.86

=50.53

=78.64

0

2

4

6

8

10

12

MA

R'9

5 4 7 10 13 16 19 22 25 28 31

Time Window (March 1995)

Rad

on C

onc.

(Bq/

L)

Soil-GasGroundwater

Χ+2 σ

Χ+2 σ

Χ−2 σ

Χ

Χ

ChambaEq. (M=5.1)

=4.73

=4.52

(Virk et al., 1995)

Dalhousie

0

10

20

30

40

50

60

70

80

Mar

. 99 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Time window (March 1999)

Rad

on C

onc.

(Bq/

L)

GroundwaterSoil-gas

⎯Χ+2σ = 46.63

⎯Χ+2σ =69.66

⎯Χ = 56.69

⎯Χ= 24.31

Chamoli EqM=6.8

M=3.2Ep = 87 km

(Virk et al. 2001)

Palampur

4.7

4.8

4.9

5

5.1

5.2

5.3

5.4

5.5

5.6

Mar

. 99 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Time window (March 99)

Hel

ium

Con

c. (p

pm)

Chamoli Eq

(Virk et al. 2001)

Palampur

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Mar. 99 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Time window (March 1999)

He/

Rn

(Walia et al. 2005)

Chamoli Eq

•The total number of microseismic events correlated are 63.

1.281.2844445656111114/14/15152525II. WaterII. Water

1.941.9434346666101019/19/24242929I. SoilI. Soil--gasgasDalhousieDalhousie

2.232.23313169698818/18/23232626II. WaterII. Water

1.381.3842425858151521/21/27273636I. SoilI. Soil--gasgasPalampurPalampur

Confidence Confidence levellevel

(signal/noise)(signal/noise)

NoiseNoise(%)(%)(c/a)(c/a)

SignalSignal(%)(%)

(b/a)(b/a)

No. of No. of anomalies anomalies

not not correlated correlated

with eventswith events(c)(c)

No. of No. of anomalies anomalies correlated correlated

with with eventsevents

(b)(b)

Total no. Total no. of radon of radon

anomaliesanomalies(a)(a)

StationStation

Palampur station is found to be relatively more sensitive than the Dalhousie station as a total number of 40 seismic events correlated with radon anomalies are observed at Palampur as compared to 36 events at Dalhousie in both the media.

A total of 116 radon anomalies were observed in the whole grid during the given time window and out of it 74 are correlated with seismic events.

Most of the anomalies are pre-seismic 76% whereas only 14% are co-seismic and 10% are post-seismic.

79

8070

83

40

2019

27

0

10

20

30

40

50

60

70

80

90

1992 1993 1994 1995 1996 1997 1998 1999

Time Window

No.

of E

vent

s/Ye

ar

0

5

10

15

20

25

30

Avg

. Rad

on C

onc.

/Yea

r

Seismic Events/yearAvg. Rn conc./year

Variation of Radon Conc. with Microseismicityin the region

•About 142 cases of radon anomalies in soil-gas and groundwater correlated with earthquakes of magnitude range between 2.1 to 4.8 and having epicentral distances less than 200 kms during time period 1992-1999.

•Whereas single earthquake of magnitude 4.7, 4.8, 5.1 and 6.8 were correlated with radon anomalies during the period.

•The radon behaviour observed in soil-gas and groundwater indicate that the transport phenomenon entirely different.

•The behaviour of Palampur and Dalhousie stations across the MBF is almost reciprocal. This may be due to relative motion of crustal blocks producing compressional strain on one side and dilatational strain on the other.

•Radon measurements carried out for earthquake precursory study seem to be one of the promising technique.

Thank You !!!