Unstable/Astatic Gravimeters and Marine Gravity SurveyRaianIslamEvan
This is a descriptive article on stable and unstable gravimeters. The article is mainly focused on LaCoste-Romberg and Worden gravimeters. Also, it includes marine gravity survey shortly.
Slides related to wall rock alteration.In these slides it is described that how host rock behave when it comes in contact with the hydro thermal fluid coming from deep Earth (Mantle) and their results.
Unstable/Astatic Gravimeters and Marine Gravity SurveyRaianIslamEvan
This is a descriptive article on stable and unstable gravimeters. The article is mainly focused on LaCoste-Romberg and Worden gravimeters. Also, it includes marine gravity survey shortly.
Slides related to wall rock alteration.In these slides it is described that how host rock behave when it comes in contact with the hydro thermal fluid coming from deep Earth (Mantle) and their results.
Gravity and magnetic methods are an essential part of oil exploration. They do not replace seismic. Rather, they add to it. Despite being comparatively low-resolution, they have some very big advantages.
These geophysical methods passively measure natural variations in the earth’s gravity and magnetic fields over a map area and then try to relate these variations to geologic features in the subsurface. Lacking a controlled source, such surveys are usually environmentally unobjectionable.
HYDROTHERMAL PROCESSES; Causes of deposition; Origin of Hydrothermal Fluids (or The Main Sources of Water in Hydrothermal System); The Main Steps in Hydrothermal Processes; Classification of Hydrothermal Deposits; Different Types of Hydrothermal Vein; Different styles of Hydrothermal ore deposits; Orogenic Hydrothermal Ore Deposits; Hypozonal: Orogenic, hydrothermal ore deposits; Epizonal:; Mesozonal
Information about these fluids is an invaluable aid in mineral exploration.
Conventional academic methods of analysing fluid inclusions are too slow and tedious to be of practical application in typical mineral exploration activities.
However, the academic data from numerous studies does show that CO2 is an exceptionally important indicator when exploring for most types of gold deposit.
Because the baro-acoustic decrepitation method is a rapid and reliable method to measure CO2 contents in fluids, it can be used to study a spatial array of data and it is an invaluable and practical exploration method.
Measurements of temperatures of fluid inclusions does not usually help in mineral exploration as hydrothermal minerals deposit over a wide temperature range and there is no specific temperature which is indicative of mineralisation. However, if temperatures are available on a large spatial array of samples, then temperature trends may be a useful exploration method to find the hottest part of the system, which is presumably the location of the best economic mineralisation. Baro-acoustic decrepitation is the most practical method to determine temperatures of the large numbers of samples required.
Salinities of fluid inclusions are of limited use in exploration and are difficult to measure. However, they can be used to recognise intrusion related hydrothermal systems.
It covers seismic method, gravity method, electromagnetic method, magnetic method and radiometric method. all these methods help in mineral exploration
Geophysical Challenge in Oil and Gas ProjectGilang Wiranda
The Oil and Gas industries, especially in the exploration stage rely so much on subsurface earth condition information. Geophysical methods are tools that help deliver much information to obtain good decisions in the oil and gas projects. All of it comes with some challenges in various aspect.
Gravity and magnetic methods are an essential part of oil exploration. They do not replace seismic. Rather, they add to it. Despite being comparatively low-resolution, they have some very big advantages.
These geophysical methods passively measure natural variations in the earth’s gravity and magnetic fields over a map area and then try to relate these variations to geologic features in the subsurface. Lacking a controlled source, such surveys are usually environmentally unobjectionable.
HYDROTHERMAL PROCESSES; Causes of deposition; Origin of Hydrothermal Fluids (or The Main Sources of Water in Hydrothermal System); The Main Steps in Hydrothermal Processes; Classification of Hydrothermal Deposits; Different Types of Hydrothermal Vein; Different styles of Hydrothermal ore deposits; Orogenic Hydrothermal Ore Deposits; Hypozonal: Orogenic, hydrothermal ore deposits; Epizonal:; Mesozonal
Information about these fluids is an invaluable aid in mineral exploration.
Conventional academic methods of analysing fluid inclusions are too slow and tedious to be of practical application in typical mineral exploration activities.
However, the academic data from numerous studies does show that CO2 is an exceptionally important indicator when exploring for most types of gold deposit.
Because the baro-acoustic decrepitation method is a rapid and reliable method to measure CO2 contents in fluids, it can be used to study a spatial array of data and it is an invaluable and practical exploration method.
Measurements of temperatures of fluid inclusions does not usually help in mineral exploration as hydrothermal minerals deposit over a wide temperature range and there is no specific temperature which is indicative of mineralisation. However, if temperatures are available on a large spatial array of samples, then temperature trends may be a useful exploration method to find the hottest part of the system, which is presumably the location of the best economic mineralisation. Baro-acoustic decrepitation is the most practical method to determine temperatures of the large numbers of samples required.
Salinities of fluid inclusions are of limited use in exploration and are difficult to measure. However, they can be used to recognise intrusion related hydrothermal systems.
It covers seismic method, gravity method, electromagnetic method, magnetic method and radiometric method. all these methods help in mineral exploration
Geophysical Challenge in Oil and Gas ProjectGilang Wiranda
The Oil and Gas industries, especially in the exploration stage rely so much on subsurface earth condition information. Geophysical methods are tools that help deliver much information to obtain good decisions in the oil and gas projects. All of it comes with some challenges in various aspect.
Geo Environmental Investigation of Abuad Dumpsite, Southwestern NigeriaIJERA Editor
Geoenvironmental study of ABUAD female dumpsite was conducted to investigate the suitability of its location
and potential impact on groundwater in the environment. Profiling and Vertical electrical sounding methods
were employed using Dipole - Dipole and Schlumberger configuration respectively. Five points were sounded
and one profile was occupied. Three heterogeneous subsurface lithologic units were established namely; lateritic
topsoil, clayey-sand, and, fresh basement. The curve types are simple H and HA. The topsoil and clayey-sand
materials are characterized with relatively low resistivity values while the fresh basement materials are
characterized with high resistivity values. The average resistivity and thickness values for the topsoil are
280.0Ωm and.2.3m respectively. Clayey-sand was encountered in all the locations with average resistivity and
thickness values of 32.0Ωm and 7.3m respectively. Basement is relatively shallow in the study area, it was
encountered in all the locations with an average resistivity and depth values to the top of basement of 674Ωm,
and 9.6m respectively. Overburden materials are relatively thin within the area with an average resistivity and
thickness values of 156Ωm, and 9.6m respectively. The overburden materials constituting the aquiferous units
within the study area are porous, vulnerable, and good paths for leachate migration. The relatively low
resistivity values within the clayey-sand layers (14 - 61Ωm) are suggestive of leachate intrusion, while relatively
high resistivity values of the impervious basement are due to their crystalline nature. The proximity of the
dumpsite to both the cafeteria and residential halls is a cause for concern.
Geophysical methods in Hydrocarbon ExplorationRaboon Redar
Geophysical studies of the earth's interior include measurements on or near to the earth's surface that are dependent upon the physical properties of the internal distribution. Examination of these measurements can show how vertically and laterally the physical properties of the Earth's interior differ. Through operating on different scales, geophysical techniques can be used to investigate the localized upper crust area for engineering or other purposes.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Application of Geophysical and Remote Sensing Techniques to Delineate Laterit...Premier Publishers
Application of geophysical and remote sensing techniques was used to delineate lateritic bauxite zone in Orin Ekiti, Southwestern Nigeria. Three basic methods were employed to qualitatively define and identify plausible areas or zones of bauxite ore deposit within the study area. The remote sensing data utilized for the study were the Landsat (ETM) image and Shuttle Radar Topography Mission (SRTM) data in Digital Elevation Model (DEM) image. From the processed remote sensing data, features like topography, vegetation, settlements, and rocks which are all favourable features for bauxite formation were all observed and delineated. The use of magnetic method through the use of high resolution aeromagnetic data (HRAD) of sheet 224, enables different enhancement magnetic maps to be generated. These maps were used to define boundaries, contacts and edges of different rock types within the study area, and the production of a mineralization potential map for the study area. Three major rock types were identified and mapped, these are magmatite, granite gneiss and charnockite rocks. Charnockite rocks which are considered as parent rock for bauxite have low magnetic susceptibility values; therefore, zones of low magnetic susceptibility are mapped, with values ranged between -92.4 nT to -56.9nT, observed at central part trending in the east to west, and also in the northwestern and southwestern parts of the study area. Five traverses were established for electrical resistivity imaging (ERI). Bauxite being a weathered product of charnockite rock, zones of its existence is expected to have high resistivity values. So, along the five traverses, zones of high resistivity values were mapped as bauxite zones, having value ranged between 600 Ωm to 101404Ωm, and occurred within the depth ranged between 0 (surface) to maximum depth probed (15m). All the techniques adopted in the investigation showed the bauxite deposits within the study area are surficial or near-surface occurrence.
This presentation is all about Petroleum Engineering, Prospecting oil and gas, drilling and various drilling methods, logs and its types, different Drive Mechanisms, etc......
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
Geophysics
1. TECHNICAL ENGLISH - I
Introduction to Geophysics
Technical English I – Fall Term 2013-2014
Department of Geophysical Engineering
2. GEOPHYSICS
GEOPHYSICS, AS ITS NAME INDICATES, HAS TO DO
WITH THE PHYSICS OF THE EARTH AND ITS
ATMOSPHERE. GILBERT’S DISCOVERY THAT THE
EARTH BEHAVES AS A GREAT AND RATHER
IRREGULAR MAGNET AND NEWTON’S THEORY OF
GRAVITATION MAY BE SAID TO CONSTITUTE THE
BEGINNING OF GEOPHYSICS. THE CONTINUED
EXPANSION IN DEMAND FOR METALS OF ALL
KINDS AND THE ENORMOUS INCREASE IN THE
USE OF PETROLEUM PRODUCTS HAVE LED TO
THE DEVELOPMENT OF MANY GEOPHYSICAL
TECHNIQUES OF EVER-INCREASING SENSITIVITY
FOR THE DETECTION AND MAPPING OF UNSEEN
DEPOSITS AND STRUCTURES.
3. BECAUSE THE GREAT MAJORITY OF
MINERAL DEPOSITS ARE BENEATH THE
SURFACE, THEIR DETECTION DEPENDS ON
THOSE CHARACTERISTICS THAT
DIFFERENTIATE THEM FROM THE
SURROUNDING MEDIA. METHODS BASED
ON VARIATIONS IN THE ELASTIC
PROPERTIES OF ROCKS HAVE BEEN
DEVELOPED FOR DETERMING
STRUCTURES ASSOCIATED WITH OIL AND
GAS, SUCH AS FAULTS, ANTICLINES, AND
SYNCLINES SEVERAL KILOMETERS BELOW
THE SURFACE.
4. THE VARIATION IN ELECTRICAL
CONDUCTIVITY AND NATURAL CURRENTS
IN THE EARTH, RATES OF DECAY OF
ARTICIAL POTENTIAL DIFFERENCES
INTRODUCED INTO GROUND, LOCAL
CHANGES IN GRAVITY, MAGNETISM AND
RADIOACTIVITY – ALL THESE PROVIDE
INFORMATION ABOUT THE NATURE OF
STRUCTURES BELOW THE SURFACE, THUS
PERMITTING GEOPHYSICISTS TO
DETERMINE THE MOST FAVORABLE
PLACES TO SEARCH FOR MINERAL
DEPOSITS.
5. GEOPHYSICS DEALS WITH ALL ASPECTS OF THE
PHYSICS OF THE EARTH, ITS ATMOSPHERE, AND
SPACE. GEOPHYSICAL MEASUREMENTS WERE
MADE BY THE MAN LANDED ON THE MOON, AND
THE ATMOSPHERES, MAGNETIC FIELDS, AND
OTHER PROPERTIES OF PLANETS ARE
STUDIEDUSING GEOPHYSICAL DATA OBTAINED
BY UNMANNED SPACECRAFT. THE PRINCIPAL
SUBDIVISIONS OF GEOPHYSICS ARE AS
FOLLOWS; SOME OF THESE HAVE BEEN
INVESTIGATED FOR MANY YEARS SIMPLY
BECAUSE OF THEIR SCINTIFIC INTEREST:
6. SEISMOLOGY
THERMAL PROPERTIES OF EARTH
TERRESTRIAL MAGNETSM
TELLURIC CURRENTS
GEODESY AND GRAVITATION
RADIOACTIVITY OF THE EARTH, SEA, AND
ATMOSHERE; COSMIC RAYS
ATMOSPHERIC ELECTRICITY
METEREOLOGY
OUR KNOWLEDGE OF EARTH HAS BEEN
DEVELOPED BY COMBINING
INFORMATION FROM ALL THESE DATA.
7. APPLIED GEOPHYSICS IN THE SEARCH
FOR MINERALS, OIL, AND GAS MAY BE
DIVIDED INTO FOLLOWING METHODS OF
EXPLORATION:
GRAVITATIONAL
MAGNETIC
SEISMIC
ELECTRICAL
ELECTROMAGNETIC
RADIOACTIVITY
WELL LOGGING
MISCELLANEOUS CHEMICAL, THERMAL,
AND OTHER METHODS
8. GEOPHYSICAL PROSPECTING
GEOPHYSICAL PROSPECTING IS THE
ART OF SEARCHING FOR CONCEALED
DEPOSITS OF HYDROCARBONS (OIL
AND GAS) OR USEFUL MINERALS BY
PHYSICAL MEASUREMENTS FROM THE
EARTH’S SURFACE. ORDINARILY,
THESE MEASUREMENTS YIELD
INFORMATION ON THE PHYSICAL
PROPERTIES OF MATERIAL WITHIN
THE EARTH.
9. SUCH INFORMATION, WHEN PROPERLY
INTERPRETED, CAN BE USED TO LOCATE
MINERAL DEPOSITS HAVING ECONOMIC
VALUE. TO BE EFFECTIVE FOR THIS
PURPOSE, THE DATA FROM GEOPHYSICAL
SURVEYS MUST BE EXPRESSED IN TERMS
OF GEOLOGY. THE RELIABILITY OF THE
GEOLOGICAL PICTURE THUS DERIVED,
WHICH IS GREATER FOR SOME
TECHNIQUES THAN OTHERS, DEPENDS ON
THE QUALITY OF THE DATA AND THE SKILL
DISPLAYED IN THEIR INTERPRETATION.
10. EVER SINCE GEOPHYSICS WAS FIRST
USED IN EXPLORATION, THERE HAS
BEEN CONTINUAL IMPROVEMENT
BOTH IN INSTRUMENTS AND
TECHNIQUES IN METHODS OF
INTERPRETATION. THESE
IMPROVEMENTS HAVE TAKEN FULL
ADVANTAGE OF OUR RAPIDLY
ADVANCING TECHNOLOGY
SPECIFICALLY INCREDIBLE HURDLES
IN DIGITAL ELECTRONICS.
11. GEOPHYSICAL METHODS HAVE
BECOME MORE EFFECTIVE BUT THEIR
INCREASED CAPABILITIES HAVE NOT
QUITE KEPT PACE WITH THE
INCREASING DIFFICULTY OF FINDING
NEW OIL AND MINERALS AS SOURCES
EASIEST TO LOCATE AT ANY TIME ARE
PROGRESSIVELY FOUND AND
EXPLOITED. GEOPHYSICISTS NOW
FACE THE DISCOURAGING, PROBLEM
OF HAVING TO RUN FASTER AND
FASTER TO STAY IN THE SAME PLACE.
12. GEOPHYSICS IN THE OIL
INDUSTRY
WHEN THE EARLIEST CREWS, USING
THE TORSION BALANCE AND
REFRACTION SEISMOGRAPH, LOOKED
FOR SHALLOW SALT DOMES ALONG
THE GULF COAST OF THE UNITED
STATES AND MEXICO DURING THE
MIDDLE OF 1920’S, THEIR EFFORTS
WERE SPECTACULARLY SUCCESSFUL.
13. LARGER POOLS THAT WERE EASY TO
DISCOVER BY GEOPHYSICS HAVE
BEEN MOSTLY FOUND, SO THAT THE
INDUSTRY IS WILLING TO DRILL ON
MORE MODEST PROSPECTS AS THE
GOOD ONES HAVE BECOME SCARCER.
THUS, A GREATER NUMBER OF
GEOPHYSICAL CREWS IS NECESSARY
TO LOCATE THE SAME NUMBER OF
BARRELS OF OIL EACH SUCCESSIVE
YEAR SO THAT EXPLORATION COSTS
PER BARREL INCREASE.
14. MANY OIL COMPANIES HAVE BEEN
MEETING THIS PROBLEM BY
EXPANDING THEIR OPERATIONS
WORLDWIDE. OTHERS HAVE BEEN
CONCENTRATING ON OFFSHORE
EXPLORATION, WHERE GEOPHYSICS
HAS BEEN NOTABLY SUCCESSFUL.
FOREIGN OPERATIONS ARE QUITE
EXPENSIVE AND OFTEN INVOLVE
POLITICAL RISK WHILE OFFSHORE
LEASING AND PRODUCTION ARE VERY
COSTLY.
15. GEOPHYSICS IN MINING
EXPLORATION
BY THE GREATEST PORTION OF THE
ACTIVITY IN GEOPHYSICAL PROSPECTING
HAS BEEN IN THE SEARCH FOR OIL AND
GAS. ONLY A SMALL FRACTION OF THIS
EFFORT HAS GONE INTO THE SEARCH FOR
SOLID MINERALS. YET GEOPHYSICAL
METHOD WERE USED TO EXPLORE FOR
ORES SEVERAL CENTRUIES BEFORE THERE
WAS ANY OIL INDUSTRY AT ALL.
16. ALTHOUGH THE TOTAL EXTENT OF
GEOPHYSICAL WORK IN THE MINERAL
INDUSTRY IS SMALL COMPARED TO
THAT IN THE PETROLEUM INDUSTRY,
GEOPHYSICAL SURVEYS RESULTED IN
SOME SPECTACULAR DISCOVERIES OF
ORE DEPOSITS. THERE ARE A NUMBER
OF REASONS WHY GEOPHYSICS HAS
LESS WIDESPREAD APPLICATION IN
MINERAL PROSPECTING THAN OIL
AND GAS EXPLORATION.
17. IN THE FIRST PLACE, THE PHYSICAL
PROPERTIES OF MANY ORE BODIES DO NOT
SHOW SUBSTANTIAL CONTRASTS WITH
THE CORRESPONDING PROPERTIES OF THE
COUNTRY ROCK WHICH SURROUNDS
THEM. THUS THERE ARE MANY DEPOSITS
WHICH ARE NOT INTRINSICALLY
PROMISING AS GEOPHYSICAL TARGETS.
MOREOVER, MINING COMPANIES TEND TO
BE SMALLERAND MANY CANNOT AFFORD
THE NECESSARY OUTLAY FOR
GEOPHYSICAL WORK.
18. EXPLORATION GEOPHYSICS AND
THE BASIC SCIENCES
ONE OF THE MOST RECENTLY
ESTABLISHED BRANCHES OF APPLIED
SCIENCE, EXPLORATION GEOPHYSICS
IS ACTUALLY AN OFFSHOOT OF
SEVERAL BASIC DISCIPLINES, SUCH AS
PHYSICS, CHEMISTRY, AND
MATHEMATICS.
19. THE VARIOUS TECHNIQUES OF
GEOPHYSICAL PROSPECTING ARE
BASED ON A NUMBER OF
FUNDAMENTAL PRINCIPLES OF
PHYSICS, SUCH AS THE LAWS OF
GRAVITATIONAL AND MAGNETIC
ATTRACTION, THE LAWS GOVERNING
REFLECTION AND REFRACTION IN
OPTICS (AS APPLIED TO SEISMIC
PROSPECTING), AND THE ELEMENTS
OF ELECTRICITY AND
ELECTROMAGNETIC THEORY.
20. ALTHOUGH THESE PRINCIPLES ARE QUITE
SIMPLE, IT IS GENERALLY DIFFICULT TO
APPLY THEM TO THE STUDY OF ROCK
MATERIALS, WHICH ARE SELDOM
HOMOGENEOUS AND WHICH OFTEN HAVE
COMPLEX PHYSICAL PROPERTIES. NEARLY
ALL THE MAJOR METHODS OF
GEOPHYSICAL PROSPECTING EVOLVED
FROM TECHNIQUES ORIGINALLY
EMPLOYED FOR MORE OR LESS ACADEMIC
STUDIES OF THE EARTH’S LARGE-SCALE
FEATURES.
21. GRAVITY PROSPECTING WAS DEVELOPED
AFTER PENDULUM MEASUREMENTS HAD
BEEN CARRIED OUT FOR SEVERAL
DECADES FOR SEVERAL DECADES TO
DETERMINE THE EARTH’S PRECISE SHAPE
FROM CHANGES IN GRAVITATIONAL PULL
BETWEEN DIFFERENT OBSERVING
STATIONS. THE SEISMIC REFRACTION
METHOD MAKES USE OF PRINCIPLES
WORKED OUT EARLY IN THE PAST
CENTURY BY EARTHQUAKE SEISMOLOGIST
WHO DEVELOPED THEM TO UNRAVEL THE
STRUCTURE OF TRHE EARTH’S INTERIOR.
22. MAGNETIC INSTRUMENTS WHICH WERE
BASICALLY THE SAME AS THOSE USED IN
PRESENT-DAY PROSPECTING MADE IT
POSSIBLE TO CHART SOME OF THE
EARTH’S MAGNETIC ELEMENTS ON A
GLOBAL SCALE AS EARLY AS THE
SEVENTEENTH CENTURY. TODAY THERE IS
A MUCH GREATER VOLUME OF ACTIVITY
IN GEOPHYSICAL EXPLORATION THAN IN
BASIC RESEARCH ON THE PHYSICS OF
EARTH.
23. SEISMIC REFLECTION METHOD
WITH THIS TECHNIQUE, THE STRUCTURE OF
SUBSURFACE FORMATIONS IS MAPPED BY
MAKING USE OF THE TIMES REQUIRED FOR A
SEISMIC WAVE (OR PULSE), GENERATED IN THE
EARTH BY A NEAR-SURFACE EXPLOSION OF
DYNAMITE, RETURN TO THE SURFACE AFTER
REFLECTION FROM THE FORMATIONS
THEMSELVES. THE REFLECTIONS ARE
RECORDED BY DETECTING INSTRUMENTS
RESPONSIVE TO GROUND MOTIONS, WHICH ARE
LAID ALONG THE GROUND NEAR THE SHOT
HOLE
24. DEPTHS TO REFLECTING INTERFACES CAN
BE DETERMINED FROM THE TIMES IF
VELOCITY OF SEISMIC WAVES IN THE
OVERLYING THE SECTION CAN BE
MEASURED. THE REFLECTION TECHNIQUE
FURNISHES MORE AND BETTER
STRUCTURAL INFORMATION THAN ANY
OTHER GEOPHYSICAL METHOD, BUT IT
HAS THE DISADVANTAGE OF BEING
SLOWER AND MORE EXPENSIVE.
MOREOVER, THERE ARE NUMEROUS AREAS
WHERE REFLECTIONS CAN BE OBTAINED
ONLY WITH GREAT DIFFICULTY.