New Magnetic Observatory Installation In Oaxaca, Mexico IAGA 2008 Golden, Colorado, USA Ivan Hrvoic,...
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Transcript of New Magnetic Observatory Installation In Oaxaca, Mexico IAGA 2008 Golden, Colorado, USA Ivan Hrvoic,...
New Magnetic Observatory Installation
In Oaxaca, Mexico
IAGA 2008Golden, Colorado, USA
Ivan Hrvoic, Enrique Cabral, Esteban Hernandez, Gerardo Cifuentes, Mike Wilson, Francisco Lopez
Overview
• Overview of SuperGradiometer Installation
• Introduction of Potassium dIdD
• Summary and Conclusions
Overview of SuperGradiometer Installation
– Instrumentation– SuperGradiometer Features– SuperGradiometer Array– UNAM-GEM Cooperation– Site Location, Selection and Data– Sensor Installation– Sample of Data Records– Sensor Field Inclinations and Declinations
Instrumentation
• Most Sensitive Scalar Magnetometer• Based on Optically Pumped Potassium• Very high sampling (up to 20 samples / second)
• Designed for minimal heading error, high absolute accuracy and reliability
SuperGradiometer Features
• Delivers sensitivity needed for Short Base or Gradiometric work in Earthquake Studies
• Background noise is 50 fT for 1 reading / second
• Can increase sensitivity further by placing sensors at specific distances, say 50 to 100m, which gives 1 fT/m gradient sensitivity
• 3 sensors arranged according to terrain (horizontal or vertical)
• Sensor spacing up to 140m• Long term integration is promising
SuperGradiometer Array
UNAM-GEM Cooperation
• Geophysics Department of UNAM expressed interest in deployment in Mexico
• Discussions about experimental deployment of SuperGradiometer for Earthquake studies
• Site selection possibilities
Site Location: Oaxaca, Mexico
Site Location: Oaxaca, Mexico
Site of Mexican Supergrad is at 1751171 latitude and 745773 longitude.
Site Location: Oaxaca, Mexico
El Trapiche San Francisco CozoaltepecSanta Maria Tonameca, Oaxaca
Site Selection: Survey
Overhauser Gradiometer Survey
Site Selection: Data
30 pT
Gradiometric Survey Map
Site Selection: Sensor Location
Sensor Installation: Pillars
Powering the System
14 Batteries = 420 Ah
23 Solar Panels = 920 watts
(38 Ah)
Data Transfer
Upstream 300 Kbps
Static IP Address
Initial Setup with Local and Base (not shown) Towers
Currently upgrading to Satellite
• SG Total Field record
39045400
39045600
39045800
39046000
39046200
39046400
39046600
39046800
39047000
39047200
39047400
39047600
39047800
39048000
39048200
39048400
39048600
39048800
39049000
39049200
39049400
39049600
39049800
39050000
39050200
39050400
pT
• SG Gradient 12 hr
• SG Gradients record
21040
21045
21050
21055
21060
21065
21070
21075
21080
21085
21090
21095
21100
21105
21110
21115
21120
pT
Sensor Field Inclination and Declination
Sensor 1: I = 43.16, D = 5.11º
Sensor 2: I = 43.12º, D = 5.05º
Sensor 3: I = 43.19º, D = 5.27º
Introduction of Potassium dIdD
– Correction of Diurnals in Gradients & Israeli Experience
– Potassium dIdD– Site Selection– Sensor Installation– Satellite View of Site– Experimental Results
Correction of Diurnals in Gradients& Israeli Experience
Example of magnetic monitoring
a) Difference G21= F2-F1
b) Difference G32= F3-F2
c) Y component of magnetic field
d) X component of magnetic field
e) Z component of magnetic field
Correction of Diurnals in Gradients& Israeli Experience
Leveled SuperGrad differences after ‘cleaning’ procedure.a) Difference Gcorr21b) Difference Gcorr32
Potassium dIdD GSMP-35 dIdDIn the past, some magnetic observatories
relied on a combination of Overhauser dIdD, and theodolite instruments for obtaining measurements.
GEM introduces new GSMP-35 dIdD (delta Inclination / delta Declination) system for high precision results (maximum 5 readings per second, 15pT sensitivity at 1 reading per second).
Now, the dIdD has been enhanced significantly with the development of the Suspended dIdD system with potassium sensor.
Site Selection: Survey
Site Selection: Data
Gradient in dIdD 0.03 nT
Site Selection: Sensors Location
The distance from dIdD to:Solar Panel 65 mSG/CPU 70 mSensor 1 150 mSensor 2 110 mSensor3 80 m
dIdD Installation: Pillar
Satellite View of Site
SG = SuperGrad consoledIdD = dIdD systemS1 = Sensor 1S2 = Sensor 2S3 = Sensor 3Solar= Solar panels and batteries
Experimental Results
Summary and Conclusions
• We have tried to establish reference conditions to detect magnetic precursors of Earthquakes based on known precursors.
• While trying to eliminate influence of diurnal variations of magnetic field, a need for a high sensitivity measurement of components arose.
• We introduced a Potassium DIDD with some 15pT sensitivity, thus setting up possible new standards for a high sensitivity magnetic observatory