Preliminary Results of Latitudinal Dependence of Pc3-4 Amplitudes at 96º MM Stations in Africa

Preliminary Results of Latitudinal Dependence of Pc3-4 Amplitudes at 96º MM

Stations in Africa

Takla E. M.[1]; K. Yumoto[1,2]; M. G. Cardinal[1]; A. Mahrous[3]; G. Mengistu[4]; T. Afullo[5]; A. Macamo[6]; L. Joao[6]; N. Mwiinga[7]; C. Uiso[8]; P. Baki[9]; G. Kianji[9]; K. Badi[10]; S. Malinga[11]; A. Meloni[12]; S. Abe[2]; T. Uozumi[2]; A. Fujimoto[1]; A. Ikeda[1]; T. Tokunaga[1] and Y. Yamazaki[1].

[1] Dept. of Earth and Planetary Sci., Kyushu Univ.; [2] Space Environ. Res. Center, Kyushu Univ.; [3] SWMC, Helwan Univ., Egypt; [4]Dept. of Phys. Addis Ababa Univ., Ethiopia; [5] Dept. of Elec. Engineering Univ. of Kwazulu-Natal, South Africa; [6] Dept. of Phys., Eduardo Mondlane Univ., Mozambique; [7] Dept. of Physics, Univ. of Zambia; [8] Dept. of Phys., Univ. of Dar es Salaam, Tanzania; [9] Dept. of Phys., Nairobi Univ., Kenya; [10] Dept. of Eng., Sudan Univ. of Sci. and Tec.; [11] Hermanus Mag. Observatory, South Africa; [12] INGV, Italy.

ByBy

1-Motivation2-Introduction and aim of research3-Results & Discussion4-Conclusion5-Future Work

Outline2

31-Motivation

1-1 Seismic hazard in Africa

Gulf of Aqaba–dead sea Gulf of Aqaba–dead sea shear zoneshear zone

Great Rift Great Rift ValleyValley

1-2 MAGDAS stations in Africa4

Abbrev.

StationName

Nation GG Lat.GG Lon

.

GM Lat.

GM Lon.

Install

FYM Fayum Egypt 29.18 35.5 25.76 112.6514/1/200

8

ASW Aswan Egypt 23.59 32.51 15.2 104.2423/12/20

08

KRT Khartoum Sudan 15.33 32.32 5.69 103.823/9/200

8

AAB Adis Ababa Ethiopia 9.04 38.77 0.18 110.4719/8/200

6

ILR Ilorin Nigeria 8.5 4.68 1.82 76.824/8/200

6

LAG Lagos Nigeria 6.48 3.27 -3.04 75.33 4/9/2008

ABJ AbidjanIvory

Coast5.35 3.08 -6.32 69.23 1/9/2006

NAB Nairobi Kenya -1.16 36.48 -10.65 108.1816/9/200

8

DESDar EsSalaam

Tanzania -6.47 39.12 -16.26 110.5910/9/200

8

LSK Lusaka Zambia -15.23 28.2 -26.06 98.3225/9/200

8

MPT MaputoMozambiq

ue-25.57 32.36 -35.98 99.57

15/9/2008

DRB DurbanSouth

Africa-29.49 30.56 -39.21 96.1 8/9/2008

HER HermanusSouth

Africa-34.34 19.24 -42.29 82.2

14/9/2007

5

1-3 Locations of African stations

MagneticField

Main FieldMain FieldMain FieldMain Field External FieldExternal FieldExternal FieldExternal Field CrustalCrustal FieldFieldCrustalCrustal FieldField

Generated internallyFrom the outer coreGenerated internallyFrom the outer core

Electric currents in the ionosphere,

particles ionized by solar radiation

Electric currents in the ionosphere,

particles ionized by solar radiation

Variations caused by local magnetic

anomalies in the earth’s crust

Variations caused by local magnetic

anomalies in the earth’s crust

2- Introduction 2-1 Components of Geomagnetic Field

6

≈ 97 % Main Field ≈ 2 % External Field ≈ 1% Crustal Field

Pulsations observed on the ground

Solar Wind

MagnetosphereIonosphere

Lithosphere

2-3 The Ultra low Frequency (ULF) Signals

The magnetic pulsations (ULF waves) that observed at the Earth's surface are a combination from:

1- ULF Waves produced by processes in the magnetosphere and solar wind

2- ULF pulsations associated with seismic and volcanic activity.

LTBfA

A ： amplitude of ULF pulsation

B ： source wave

f(LT) ： local time dependence

σ:amplification factor

[Chi et al.,1996]

Space origin

Lithosphere origin

Wave Form Classes Period [s] Frequency [mHz]

Continuous Pc

Pc1 0.2 – 5 200 – 5000

Pc2 5 –10 100 – 200

Pc3 10 – 45 22 – 100

Pc4 45 –150 6.6 – 22

Pc5 150 – 600 1.6 – 6.6

Irregular Pi

Pi1 1 – 40 25 – 100

Pi2 40 – 150 6.6 – 25

2-4 Classifications of ULF waves

The ultra-low-frequency (ULF) waves cover roughly the frequency range from 1 mHz to 1 Hz

8

2-5 Aim of Research

In order to examine or identify the ULF anomalies associated with seismic activities, we need to understand the characteristics of these pulsations. So the purpose of

this study is to clarify the characteristic properties of Pc3-4 in Africa through MAGDAS data as a preceding step for

studying the geomagnetic anomalies associated with seismic activity in Africa.

9

3- Results and Discussion Power spectrum for H component

10

Pc3 H-Component Pc3 D-Component 11

Pc3 H-Component

Pc4 H-Component Pc4 D-Component 13

Pc4 H-Component Pc4 D-Component 14

Pc4 H-Component

Latitudinal dependence of Pc3 amplitude 16

Latitudinal dependence of Pc4 amplitude

Surface W ave

Transmitted Com pressional W ave

Upstream W ave

Bow ShockMagnetopause

1)Upstream waves 2)Surface waves

The Source of Pc3-4 The Source of Pc3-4 pulsationspulsations

18

Shielding Effect

KR T

A AB

N A B

D ESLS K

M PT

LAQ

H E RFY MAS W

D ip Equator

A- Pc3 Pulsa tion

B- Ionospheric Induction C urrents

C- Observed Pc3

Yoshikawa et al., 2002

4- Conclusion• There is no enhancement in the Equatorial Pc3.• The D-component Pc3 is much smaller than the H-

component Pc3.• There is an enhancement in the Equatorial Pc4

pulsation• The D-component Pc4 is much smaller than the H-

component Pc4.

Therefore, we conclude that equatorial Pc3 maybe originated from the upstream region. On the other hand, equatorial Pc4 maybe originated from Pc4 excited at mid or high latitudes.

19

• Study the annual variations of equatorial Pc3-4 pulsations.

• Study the ULF anomalies associated with seismic activities in Africa

5-Future Work5-Future Work 20

Thank Youありがとうございまし

た

21