BASE GEOPHYSICS

The physical properties of the Earth such as internal structure, density , pressure and elasticity is provided by means of seismic waves study.  However the  contribution of mineralogical and petrological studies are not undermined when it comes to revealing the facts about the interior of the Earth. Through this post, you will learn the facts about Earth's internal structure! There are discontinuities that separate Earth into layers based on either rock properties or seismic velocity changes. Moho is the term that is frequently used which means Depth They are described as follows here down, i/ Seismological Moho This is the depth at which the P - wave velocity exceeds 7.6 kms -1 ii/ Petrological Moho This is the depth where rock types change. Based on above Moho the following internal discontinuities of the Earth are derived, 1: Gutenberg Discontinuity This lies between the Mantle and Core part of the Earth. 2: Mohorovic Discontinuity This lies between the Crust and the M...

Seismic data acquisition is the systematic process at which the modified seismic waves from seismic reflectors are recorded by various seismic receivers such as geophones or hydrophones . That is simple to define, however to know the way through which this process occurs is very important as this will give you an idea  when dealing with seismic interpretation tasks. And this is why I have written this piece of article to help you to have an idea on how seismic surveys can be carried out. There are two common techniques at which field seismic data acquisition can be conducted, these are 2-D and 3-D techniques. Due to advancing in technology there is another term known as 4D - seismic technique especially in oil and gas industry , However deciding which one you can deploy will depend on various factors such as geophysical seismic objectives, budget, size of survey area, nature of geological terrain being surveyed. Let's start to describe these terms in more convenient man...

Self potential (SP) method is the one of passive form amongst electrical geophysical techniques. This is because self-potential signals originate naturally in the ground. This means that the SP signals are recorded with no need of applying electrical signals into the subsurface. The self- potential is generated itself within the Earth's ground due to various electrochemical processes such as electrical filtration , diffusion , adsorption and others as I will describe later in details. However the technique is based on a simple model where the generated natural ground potential difference (P.d) is measured in millivolts (mV) between two (2) points. Origin  (mechanism) of self - potential  1. Electrokinetic (Ek) potential Flowing of fluid (electrolyte) through a capillary or porous medium generates potentials along the flow path. The potentials are alternatively called electrofiltration , electromechanical or streaming potentials . The effect is believed to be due to electro...