Principal component analysis of geomaPrincipal component analysis of geomagnetic data associated with Panzhihua gnetic data associated with Panzhihua

Ms 6.1 earthquakeMs 6.1 earthquake - the preparatory result- the preparatory result

Li JunhuiLi Junhui11 、、 33 Li Qi Li Qi22 Yang Dongmei Yang Dongmei22

1 Seismological Bureau of Anhui, Hefei, China. 1 Seismological Bureau of Anhui, Hefei, China. 2 Institutes of Geophysics, CEA, Beijing 2 Institutes of Geophysics, CEA, Beijing

33 、、 National Geophysical Observatory at MengchengNational Geophysical Observatory at Mengcheng ，， Hefei 230031 e-Hefei 230031 e-mailmail ：： lijunhui@mail.ustc.edu.cnlijunhui@mail.ustc.edu.cn

Table of contentsTable of contents

Ms 6.1 Pan Zhihua earthquake and Ms 6.1 Pan Zhihua earthquake and observations site.

PCA methodPCA method

PCA result of this earthquakePCA result of this earthquake

Discussion and conclusionDiscussion and conclusion

Wenchuan earthquake sequenceWenchuan earthquake sequence

Ms 6.1About 600Km far

from Ms 8.0

一、 about this earthquake

Stations and EarthquakeStations and Earthquake

西昌台阵西昌台阵 99 个磁个磁通门仪器。通门仪器。

88 月月 3030 日日 1616 点点发生发生 Ms6.1Ms6.1 级地级地震。震。

距最近的台站平距最近的台站平地仅地仅 6.4Km6.4Km 、、南山南山 40Km40Km 、会、会理理 60Km.60Km.

仪器：仪器： GM4GM4

Technical parameter of GM4Technical parameter of GM4

ULF geomagnetic dataULF geomagnetic data• ComponentsComponents Geomagnetic 3 component Geomagnetic 3 component

（（ H, D[declination], Z[vertical]H, D[declination], Z[vertical] ））• ObservatoryObservatory Nanshan HUILi PingdiNanshan HUILi Pingdi• SamplingSampling 1Hz1Hz• Analysis termAnalysis term Jan 1 Jan 1 200 20088 – Dec 31 200 – Dec 31 20088• Feb march April No data Feb march April No data

二、二、 procedure of PCAprocedure of PCA

Data: second;Data: second; Stations: NSHStations: NSH 、、 HLCHLC 、、 Pd;Pd; 1800 point;1800 point; Y1=Dnsh(i);Y1=Dnsh(i); Y2=Dhlc(i);Y2=Dhlc(i); Y3=Dpd(i);Y3=Dpd(i); Y=[Y1,Y2,Y3];Y=[Y1,Y2,Y3];

procedure of PCAprocedure of PCA

1Hz 1Hz sample per 30 min 3 stations yNS(1:1800) ,yPD(1:1800),yHL(1:1800).

Y=[yNST, yPD

T yHLT]; Transpose matrix

variance matrix R=YYT ;

Calculate the eigenvalue of R 入 1 ，入 2 ，入 3 （入 1> 入 2> 入 3 ） .

3 temproal eigenvalue sequence

Signals observed on the ground-Signals observed on the ground-based magnetometerbased magnetometer

Katsumi Hattori 2004

Result of PCA JapanResult of PCA Japan

三、 三、 PCA result PCA result

The variation of first principal component with that of Ap index in April, 2008.

The variation of first principal componentThe variation of first principal component

The variation of second principal componentThe variation of second principal component

The variation of third principal component

analysis of the third analysis of the third principal component

选取台站周围选取台站周围100Km100Km 范围范围内地震。内地震。

计算地震释放计算地震释放能量能量

与第三主成分与第三主成分对比分析。对比分析。

The variation of third principal component 2008

Select May to SeptemberSelect May to September

四 四 Discussion and conclusionDiscussion and conclusion The first principal component is found to be thThe first principal component is found to be th

e signal originated in the solar–terrestrial effece signal originated in the solar–terrestrial effects such as geomagnetic pulsation. ts such as geomagnetic pulsation.

the second principal component, the local artithe second principal component, the local artificial noise is included.ficial noise is included.

the smallest third component in the local midthe smallest third component in the local midnight at the Panzhuhua region, it indicated incnight at the Panzhuhua region, it indicated increase in the third eigenvalue about 40 days befrease in the third eigenvalue about 40 days before the large earthquake. ore the large earthquake.

These features are likely to be correlated with These features are likely to be correlated with large earthquake. large earthquake.

Thanks allThanks all