Equipping of Eilat observatory by DIDD magnetometer.

Installation features and preliminary results.

B. Ginzburg,

Nuclear Research Center SOREQ, 81800, Yavne, Israel

 B. Shirman, Survey of Israel , 1 Lincoln St., 65220, Tel Aviv, Israel

In memory of Mr. Aviel Ron, 55Director of the Survey of Israel,

perished 31.03.02 in the terrorist act in Haifatogether with his daughter, 25 and son, 21

FM-105B fluxgate

Overhauser DIDD

Eilat magnetic observatory

( = 29 40’ ; = 3457’).

Magnetic field produced by DIDD at 3 meters from the instrument was

measured to be approx up to 2 nT.

The tunnel is dug into the basement rocks of Precambrian Amram Granite Porphyry type. Paleomagnetic measurements of rock samples were performed by Dr. Igor Tunyi and his colleagues from Slovakia Geophysical Institute: Magnetization is hard and stableCarrier of magnetization is hematite and probably ilmenite Main value of remanent polarization J = 2.9 nT,Main value of magnetic susceptibility K = 67.9.10-6 uSI,

Gradient components at the installation point were estimated as follows:

L < 5 nT/m – horizontal, along the tunnel direction;

T < 8 nT/m – horizontal, transverse to the tunnel direction;

V < 5 nT/m – vertical

U1

U2

U3

U4

U5

U6

U7

U8

U9

U1

U6

U7

U7

U8

U9

L1 L6 L7L7

L8

L9

To the entrance of the tunnel

0.5 m height

0.8 m height

30 cm 30 cm

700 mm

700 mm

140 mm

700 mm

17 22 27 01 06 11January - February 2002

30800

30840

30880

30920

30960

31000

31040H

oriz

ont (

DID

D),

nT

-120

-80

-40

0

40

80

120

Dec

linat

ion

(DID

D),

nT

29520

29560

29600

29640

29680

29720

Ver

tical

(D

IDD

), n

T Eilat obs.

-120

-80

-40

0

40

80

120

40

80

120

160

200

240

280

F l

u x

g a

t e

120

160

200

240

280

320

18 19 20 21 22 23 24 25January 2002

184

186

188

190

192

194

H d

iffer

ence

s, n

T

110

112

114

116

118

120

D d

iffer

ence

s, n

T

184

186

188

190

192

194

Z d

iffer

ence

s, n

T

30800

30850

30900

30950

31000

Hor

izon

t com

p., n

T

-150

-100

-50

0

50

Dec

linat

ion,

nT

29550

29600

29650

29700

29750V

ertic

al c

omp.

, nT

E ila t ob s.DID D rec ords & d iffe re nce s b etwe en DID D an d F luu xg ate