Possible precursors from GPS and geomagnetic anomaly

陳界宏中央研究院地球科學研究所

Stress Stress

Conductivity would be enhanced near epicenters during earthquakesZeng et al. (1995)

地震地磁異常

Seismo-magnetic emission waves Liu et al. (2006)

• Magnetic Transfer function (Parkinson, 1962; Parkinson and Jones, 1979, Zeng and Lin, 1995)

ΔZ = A∙ΔH + B∙ΔD

Coefficients A and B are transfer functions

influenced by the underlying electrical conductivity structure

ΔZ, ΔH and ΔD are derived from the magnetic data by using the Fourier transform and are frequency dependent.

• Skin effects (Cheng, 1989; Simpson and Bahr, 2005)

Dep=503(ρ/ f)1/2

Dep is depth (meter)

ρ is electrical resistivity (ohm-meter)

f is frequency (Hz)

• Relationships between ρ and depth sections near the CCU station are conducted by using the previous magnetotelluric studies

(Bertrand, 2009; Chiang, 2010)

PAzimuth (Dep)=arctan(Ar(f)/Br(f))

PMagnitude(Dep)=(Ar(f)2+Br(f)2)1/2

Methodology

2. 4

宜蘭

(5

.6)

2. 2

6 霧

台 (

6.4)

3. 2

2 台

東 (

5.0)

4. 9

花蓮

太遠

4. 1

9 花

蓮 (

5.4)

6. 6

台東

(5.

9)

4. 2

7 花

蓮 (

5.0)

6. 1

0 宜

蘭 (

6.5)

6. 1

5 花

蓮 (

5.4)

8. 1

4 花

蓮 (

5.2)

8. 1

8 台

東 (

5.2)

9. 5

台東

(5.

2)M4.5 澎湖縣政府北方 43.7 公里

10.2

0宜

蘭太

遠10

.25

高雄

(5.

5)

12.3

1 高

雄 (

5.4)

1.4

宜蘭

外海

(5.

1)

12.2

2 蘭

嶼 (

5.5)

11.2

1 台

東近

海 (

5.4)

12.3

花蓮

(5.

1)

嘉義、屏東與雲林近距離小規模地震干擾

計算方法修改

Locating earthquakes using seismo-magnetic anomalies

2013

2013

2005

Magnetic total intensity station

3-componentmagnetometer

20130306CCU HLG

24.31N 121.49E

20130316

23.68N 120.95E 0317

23.13N 120.78E 0317

CCU HLG

22.89N 121.46E 0324

YMM+HLG10km

CCU+HLG10km

0327

0323

0324 0325 0326 0328

0322032103200319

03270324 0325 0326 0328

03230322032103200319

0327 地磁異常

結論與討論• 地殼水平向西運動 1.20 – 2.1• 地殼垂直向下運動 1.20 – 2.1• 地殼垂直向上運動 2.21 – 2.27• 地磁異常 3.21 – 3.27

• 地磁多站定位方法，仍需改良1.20-2.1

2.21-2.27

327 地震影響範圍

307 地震干擾

應力逐漸達到飽和直到地震發生

水平向西垂直向下

達到飽和垂直向上

65days

54days

327