1 מדינת ישראלSTATE OF ISRAEL משרד התשתיות הלאומיותTHE MINISTRY OF NATIONAL INFRASTRUCTURES המדען הראשיOffice of the Chief Scientist קיום וקידום ניטור גיאומגנטי( גרדיומטר י) מדויק במצפה הגיאופיסי ע" ש בלוך, בהר עמרם דו" ח מסכם דו" ח מס' ES-16-14 מרכז מחקר גר ע יני שורק מחבר ים: ד' ר בוריס גינזבורג, חוקר ראשי של הפרויקט ד' ר ניצן זלומונסקי, חוקר ראשי של הפרויקט מר' אסף יניב, מהנדס הפרויקט גב' אביבית נוימן, מ הנדסת ת ו כנה מאי2014
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ק ¨ )£רר ( £¢ª ¨ ר ¢£ª § ק ק §ר ר ,¤ ¦ ש¬ פ פצ · Performing Organization Name and Address 10. Project/ Task / Work Unit No. 23 3005 ... (SuperGrad) project
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STATE OF ISRAEL מדינת ישראל
THE MINISTRY OF NATIONAL INFRASTRUCTURES משרד התשתיות הלאומיות
Office of the Chief Scientist המדען הראשי
מדויק ( יגרדיומטר) ניטור גיאומגנטי קיום וקידום
בהר עמרם, ש בלוך"במצפה הגיאופיסי ע
ח מסכם"דו
ES-16-14' ח מס"דו
יני שורקעמרכז מחקר גר של הפרויקט חוקר ראשי ,ר בוריס גינזבורג'ד :יםמחבר
של הפרויקט חוקר ראשי ,ר ניצן זלומונסקי'ד מהנדס הפרויקט , אסף יניב' מר כנהוהנדסת תמ ,אביבית נוימן' גב
גיאופיסי מדידות מדויקות של השדה המגנטי של כדור הארץ הן חלק אינטגראלי בניטורמטרת . בדרום הערבה –ש בלוך שנמצא בהר עמרם "משולב לטווח ארוך במצפה הגיאופיסי ע
המיוצר על ידי ( סופרגרד)מדויק -גרדיומטר סופר/רת מגנטומטרהניטור הגיאומגנטי בעזהיא חיפוש אנומליות בהתנהגות השדה המגנטי של כדור (GEM Systems)חברה קנדית
הסופרגרד שהותקן מכשיר. דינמיות אזוריות-הארץ הקשורות לפעילויות גיאו הגיאופיסית הוא בעל שלושה גלאים הפרוסים בתצורה המאפשרת במנהרה
מדידות מדויקות של השדה . דרום-מערב וגם בכיוון צפון-גרדיאנטים בכיוון מזרח מדידתזמניות של מרכיבי השדה הגיאומגנטי -מלוות במדידות בו (total field)המגנטי השלם
(. declination-inclination magnetometer dIdD)מגנטומטר מסוג מבוצעות על ידי . ע מבוצעות על ידי מדי נטייה שהותקנו במנהרהמדידות מדויקות של נטית הקרק
:במהלך הפרויקט ביצענו את העבודות הבאות טיפול ותחזוקה בציוד המותקן במצפה הגיאופיסי בהר עמרם
וויסות ובדיקות התקנה של מדי נטייה מדויקים
הורדת נתונים ממכשירי מדידה הנמצאים במצפה
עיבוד נתונים מוקדם של תוצאות ניטור
סנכרון ואינטגרציה של הנתונים מהערוצים השונים לבסיס נתונים אחוד
אנליזה של הנתונים.
Abstract
The aim of the long-term precise magnetic observations with the help of a supersensitive
potassium magnetometer/gradiometer (SuperGrad) project is to search for new capabilities of
the SuperGrad instrument (GEM Systems) in application to tectonic dynamics. SuperGrad
was installed in the geophysical tunnel at the southern part of the Arava Desert. Three total
field magnetic sensors of SuperGrad were placed so as to provide gradient data both in north-
south and east-west directions. Monitoring of the gradiometer differences was carried out
together with vector measurements of the Earth‟s magnetic field by means of a declination-
inclination magnetometer (dIdD). Magnetic measurements were supplemented with precise
ground tilt measurements.
During the whole project the following activity items were performed:
Maintenance of the instruments installed at Har Amram geophysical observatory;
Checking, installation, tuning and putting into operation of the instruments for ground
tilt measurements;
Acquisition and storage of the data;
Preparation of the data for integration into joint data base comprising different
geophysical channels;
Analysis of the magnetic field/gradient data together with other data registered at the
magnetic observatory.
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Maintaining and advancing precise geomagnetic
(gradiometer) monitoring at the Bloch Geophysical
Observatory (Har Amram).
Final report
Content
1. Introduction 5
2. Ground tilt measurements 7
a) Seika SBG2U/NG2U 11
b) Volksmeter VMII-2RU-GPS
c) Sherborne T233-0001-1 inclinometer 12
d) Wireless data communication channel 14
3. Magnetic field monitoring and data processing 15
3.1. Three-predictor model 17
3.2. Two-predictor model 18
3.3. Analysis of seasonal variability in regression coefficients 20
a) Temperature stability
b) dIdD stability
c) Ground tilt
d) Other possible reasons for the bias in the estimation of
regression coefficients
3.4. Data processing summary 23
4. Conclusion 24
5. References 24
Appendix1. Yearly ground tilt data acquired by the measurement
system based on Seika tilt sensor.
Appendix 2 Yearly ground tilt data acquired by the measurement
system based on VLL tilt sensor.
Appendix 3. Yearly ground tilt data acquired by the measurement
system based on Sherborne T233-0001-1 tilt sensor. 16
Appendix 4 Code for calculation of regression coefficients 39
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1. Introduction
The aim of the long-term precise magnetic observations with the help of a supersensitive
potassium magnetometer/gradiometer (SuperGrad) project is to search for new capabilities of
the SuperGrad instrument (GEM Systems) in application to tectonic dynamics. SuperGrad
was installed in the geophysical tunnel at the southern part of the Arava Desert. Three total
field magnetic sensors of SuperGrad were placed so as to get gradient data both in north-south
and east-west directions. Monitoring of the gradiometer differences was carried out together
with vector measurements of the Earth‟s magnetic field by means of a declination-inclination
magnetometer (dIdD).
Research objectives & expected significance
The research objectives of the project:
Application of modern magnetometer instrumentation with pT sensitivity for magnetic
monitoring of active faults.
To obtain magnetic field/gradient monitoring database in the Arava Rift region.
Databases of so high precision and sampling rate are unique for geomagnetic
observatories.
Using the tilt meters to obtain a first data set on earth tide induced geodynamics at the
site. This will serve as a baseline for comparison with expected model earth-tide
deformation and to identify eventual locally induced earth-tide influences in the SG
time series
To search for a relation between seismic activity and anomalous behavior of Earth
magnetic field / gradient specific features for Arava Rift region.
To integrate precise ground tilt measurements as a part of multi-sensor geophysical
monitoring.
To analyze a correlation between anomaly signatures in monitoring data in the frame
of multi-sensor approach to analysis of geodynamic associated phenomena.
The scientific significance is:
Collection of high precision monitoring data for investigation of tectonomagnetic
effect in wide frequency bandwidth.
Revelation of relation between seismic activity and anomalous behavior of Earth
magnetic field / gradient together with other geophysical fields for Arava Rift region.
Multisensor approach in active fault monitoring.
Equipment layout in the geophysical tunnel is shown in Figure 1.
Specific activity items in the course of the project included: Support and technological improvement of precise geomagnetic monitoring at
Bloch observatory
Integration of precise ground tilt measurement into multi-sensor monitoring
Regular data acquisition
Data management and data integration into unified database
Analysis of the magnetic field/gradient data together with other data registered
at the magnetic observatory
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SG3
N S
W
SG1
SG2
SG3
Flux
DIDD
R
n
SM
1 SM
2
172 m
35 m
Figure 1. Equipment layout in the geophysical tunnel
Flux – fluxgate magnetometer
SG1,2,3 – SuperGrad sensors
DIDD – component Overhauser magnetometer
DAQ – control and data acquisition equipment
Rn – radon sensors
DAQ – control and data acquisition equipment
SM1,2 – seismometer sensors
DAQ – control and data acquisition equipment
DAQ DA
Q DA
Q
20 m 20 m 36 m 43 m 18 m 35 m
DA
Q
DAQ
Tilt-
meter (Seika)
Tilt-meters
(Volksmeter
and
Sherborne)
battery compartment
Normally closed door
Normally opened door
compartment for sesmo calibration
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2. Ground tilt measurements
Continuous measurements of ground tilt are implemented by three tilt meters: Seika
SBG2U/NG2U, Volksmeter VMII-2RU-GPS, and Sherborne (T233-0001-1 Schaevitz
D/Axis) inclinometer.
a) Seika SBG2U/NG2U
The NG2U is a liquid based inclinometer sensor with integrated electronics. It features
an analog DC output. The sensor electronics require only minimal power and are in
conjunction with the capacitive primary transformer characterized by high accuracy and
high long-term stability. The measurement technique enables a linear relationship between
the angle to be measured and the output signal.
An electronics box contains two signal conditioners with a 0 ... 5V output signal each
and a highly stable supply voltage. A signal conditioner includes an active low pass filter,
whose upper cut-off frequency / settling time can be adjusted to suit the measurement task,
and noise voltage filters to guarantee the EMC.
Details of the tilt measurement setup based on Seika tilt sensor are given in Fig. 2 - 4.
Sensor SBG2U/NG2U has two analog outputs which are sampled by 16-bit A/D converter
(ADAM-4017) located at the distance of about three meters from the sensor. Since the
remaining part of the data acquisition system is installed 30 meters away, the data are
translated as RS-422 code and then converted to RS-232 format by ADAM-4520
converter. Sampling rate of A/D converter was chosen as 1 Sample/sec. Data acquisition
software averages the data, decimates them down to 1 Sample/minute, and stores in a
memory.
In the beginning of the project we used a usual desktop PC for sensor control and data
storage. However, in the process of project implementation it turned out that reliability of
this computer type is low because of fan failures in specific environmental conditions of
the site. That is why in the course of the project we changed all the desktop PC‟s in tilt
data acquisition systems for small fanless computers of fitPC type (see Fig. 2d).
System running during 2012 revealed that at least two types of standard UPS devices
featured unreliable operation under observatory conditions. Therefore, we decided to build
our own power supply system based on standard power supply and back-up battery. This
device, though having no special advanced features as in computerized UPS, provides
reliable long-term operation. The power supply system is shown in Fig.3.
Dedicated software for the system control and data acquisition and storage was written
using LabView package. Front panel of graphical user interface is shown in Fig. 5.
All the data acquired were arranged as yearly files. Graphical presentation of the data
acquired in the course of the project is given in Appendix 1 both in the form of time series
and Fourier transforms.
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Some of these Fourier graphs allow distinguishing weak peaks at specific periods of 1 day
and half a day. This, probably, can be attributed to the tidal phenomena at Red Sea which is
about 15 km to the South from the observatory site. We shall see even more pronounced
manifestations of these 1-day changes by analyzing the data acquired by more precise tilt