Soil Radon Flux in Hydrothermal Soil Radon Flux in Hydrothermal Area of the Tatun Volcano Group, Area of the Tatun Volcano Group,

N. Taiwan and its Monitoring ResultsN. Taiwan and its Monitoring Results

Tsanyao Frank YangTsanyao Frank Yang11, C.-C. Fu, C.-C. Fu11, H.Y. Wen, H.Y. Wen11, , W.L. HongW.L. Hong11, S.J. Lin, S.J. Lin22 and V. Walia and V. Walia22

1.Department of Geosciences, National Taiwan University2. National Center for Research on Earthquake Engineering,

NARL, Taiwan

0

2

4

6

8

1 0

1 2

1 4

1 6

0 .1 0 .2 0 .3 0 .4 0 .5 0 .6 0 .7 0 .8 0 .9 1 .0 1 .1 1 .2 1 .3 1 .4 >2 .4

A ges (M a)

Freq

uenc

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Fission trackAr-ArK -Ar

0 .1 0 .2 0 .3 0 .4 0 .5 0 .6 0 .7 0 .8 0 .9 1 .0 1 .1 1 .2 1 .3 1 .4 > 2 .41 .5

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年 代 （ 百 萬 年 ）

個數

頻率

Soil CO2 Station in Italy

Why CO2 & Rn ?? CO2 is, after water vapor, the most abundant gas phase

dissolved into magma. CO2 is one of the first gases to be exsolved and released

from an ascending magma. Increase in volcanic CO2 emission can be used as early

indicators of magma up-rise. Radon is trace gas and also sensitive to the magma

activity. Both CO2 and Radon sensors are commercially available

==> un-expensive and easy for continuously monitoring in corrosive environment !!

METHODMETHODCO2 flux measurement

•Soil gas sampling for gas comp and isotopic analysis by MS.

In situ soil Rn analysis

CO2 flux measurement again

Testing sites @ SYK

S7 S1

0S8

S9

S2

S5S1

S6

S4

S3

Testing sites @ SYK

Site 5

CO2 FLUX (ppm/sec)

T (℃) Radon

BEFORE

5.8 25.5 Balance value 6102.3 Bq/m3

AFTER 98 61 Temperature 32 ℃Humidity 85 %

Site 6

CO2 FLUX (ppm/sec)

T (℃) Radon

BEFORE

3.8 3.1 Balance value 4064.1 Bq/m3

AFTER 207.3 91 Temperature 29 ℃Humidity 87 %

Site 71426.7 Bq/m3

Summary of survey results

location Rn (Bq/m3)CO2 flux

(ppm/sec)3He/4He (Ra)

CO2 conc(v %)

H2S+SO2 conc (v%)

Site 1 342 0.6 1.09 5.44 0.10

Site 2 3259 368 3.76 79.01 2.58

Site 3 498 0.5 1.03 5.59 0.14

Site 4 1284 24.5 4.56 85.78 1.67

Site 5 6102 98.0 3.64 78.45 8.25

Site 6 4064 207 4.65 80.68 5.23

Site 7 1427 2.1 1.04 1.58 0.16

Site 8 3339 3.8 4.71 85.81 0.22

Site 9 15846 2926 4.80 87.10 7.65

Site 10 90 0.4 1.17 0.22 0.20

Higher CO2 flux => higher radon flux => higher magma signals

Configuration of Monitoring Station @SYKConfiguration of Monitoring Station @SYK

Equipped with: Rn & CO2 sensors which protected with plastic box and epoxy

Station @SYK

CO2 Result

CO2 & Rn Result

CONCLUSIONS The soil gases show significant magma signals (high

3He/4He ratios, CO2 flux, and total sulfurs) at SYK hydrothermal area.

The first monitoring station was successfully setup at SYK hydrothermal area in Taiwan. It is equipped with CO2 and Rn sensors, which are protected with plastic box and epoxy, and then can be used for long term monitoring under corrosive environments.

Both CO2 flux and radon concentrations show significant variations. They are correlated well with other magmatic proxy (3He/4He ratios and total sulfurs etc.) and can be used for further monitoring on the local magma activity.