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
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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
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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
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≈ 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
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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.
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3- Results and Discussion Power spectrum for H component
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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
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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.
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• 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
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