PHYSICAL LAWS OF SEISMIC WAVES
Seismic waves have the same behavior with the behavior of light wave. So the laws that apply to light waves also apply to the seismic waves.
The laws include:
1. Huygens says that the wave spreads from a point source of waves in all directions with a ball.
2. Snellius laws states that when a wave falls in the upper field boundary of two mediums which have different densities, then the wave will be refracted wave if the angle is less than or equal to the critical angle. The wave will be reflected if the arrival angle is greater than the critical angle. Wave come, wave refraction, wave reflection lies in a flat field.
The types of seismic waves,broadly divided into three types,namely :
A.Seismic wave by wave front shape
B. Seismic wave by place of spreading.
C. Seismic waves according to the way pulsate.
Wave front is a plane surface at a certain moment to distinguish the medium that has been disturbed by the medium that has not been disturbed. Wave front is a portrait of the propagation of fault-finding. Based on the wavefront shape, seismic waves can be divided into four types, namely:
Plane wave/flat generated by the source comilation. Plane wave propagates along a specific direction with a wavefront of the plane perpendicular to the direction of propagation.
Cylindrical wave generated by a uniform source of harassment and lies along a straight line. Cylindrical wave radiating to all directions perpendicular to the axis line with the same speed.
Ball wave/sferis generated by sources such as point (point source) spread in all directions towards the center of the ball or away from the center of the ball at the same speed.
Conical wave generated by the moving source. In this case, the source moves faster than the rapid propagation of the wave itself and face the wave in the form of whel/base cones.
Based on the spreading, seismic waves can be divided into two parts, namely body wave that propagates into the body through the medium and surface waves where the amplitude is weakened when getting into the medium.
Several types of surface waves:
Rayleigh waves are waves that propagate on the boundary surface only and can only travel on solid media and vibration direction opposite to the direction of propagation.
Love waves are waves that propagate only in the boundary layer alone and move on a horizontal field.
Wave tube is movement/flow of fluids along the well drilling. Fluid motion is caused by vibrations that propagate well wall in axial direction. Wave tube has three processes namely well wall contraction, to part well wall and the flow of fluid within the wellbore.
Seismic waves according to the way pulsate,divided into two kinds :
1. Primary wave (longitudinal/compussional wave) primary wave is a wave that direction vibrotion pulsate in the direction of the wave. This wave has the greatest velocity of seismic waves to another.
2. Secondary wave (transversal/shear wave) secondary wave is the wave vibration direction perpendicular to the direction of wave propagation. This wave can only propagade in solid material only and has a wave speed is much smaller than the primary wave.
Seismic methods ;one method of exploration is based on meansuring the responce of seismic waves (sound)
that is inserted into the ground and then in reflection or reflaction along different layers of soil or rock beun
daties. seismic source is generally a sledgehammer which in hit on the metal plate above the ground ,the great
mass of in drop or explosion of dynamite. Responses captured from soil measuerd whit a sensor called geophone, which measures the movement of the earth.
There are two basic kinds of seismic methods are used, the seismic refraction and seismic reflection.
Methods of measuring the refraction seismic waves the are reflection throunghout the geological formations
beneath the soil surface. Refraction events generally occur in ground water and the top of the rock bearing
rock formations. Graph of time came the first seismic waves at each geophone provides information on depth and location of these geological horizons. This information in then illustrated in a cross to indicate the depth of the water table and first layer of rock bearing rock.
Seismic reflection method to measure the time if takes a sound impulse to go from the sound source,reflected
by the boundaries of geological formations , and retruned to the soil surface at a geophone .reflections of a geological horizon is similiar to an echo on a cliff or cliff face . Seismic reflection method widely used for petroleum exploration purposes. The datemination of earthquake source or the detection of soil structure.
Seismic reflection only observe reflected waves coming from the boundaries geologi formation .
This reflected wave can be diveded into several types of waves, namely, wave-p, wave-s ,wave stonely, and the waves love.
Seismic waves have the same behavior with the behavior of light wave. So the laws that apply to light waves also apply to the seismic waves.
The laws include:
1. Huygens says that the wave spreads from a point source of waves in all directions with a ball.
2. Snellius laws states that when a wave falls in the upper field boundary of two mediums which have different densities, then the wave will be refracted wave if the angle is less than or equal to the critical angle. The wave will be reflected if the arrival angle is greater than the critical angle. Wave come, wave refraction, wave reflection lies in a flat field.
THE TYPES OF SEISMIC WAVES
The types of seismic waves,broadly divided into three types,namely :
A.Seismic wave by wave front shape
B. Seismic wave by place of spreading.
C. Seismic waves according to the way pulsate.
SEISMIC WAVE BY WAVE FRONT SHAPE
Wave front is a plane surface at a certain moment to distinguish the medium that has been disturbed by the medium that has not been disturbed. Wave front is a portrait of the propagation of fault-finding. Based on the wavefront shape, seismic waves can be divided into four types, namely:
1. WAVE FIELD
Plane wave/flat generated by the source comilation. Plane wave propagates along a specific direction with a wavefront of the plane perpendicular to the direction of propagation.
2. CYLINDRICAL WAVE
Cylindrical wave generated by a uniform source of harassment and lies along a straight line. Cylindrical wave radiating to all directions perpendicular to the axis line with the same speed.
3. BAll WAVE
Ball wave/sferis generated by sources such as point (point source) spread in all directions towards the center of the ball or away from the center of the ball at the same speed.
4. CONICAL WAVE
Conical wave generated by the moving source. In this case, the source moves faster than the rapid propagation of the wave itself and face the wave in the form of whel/base cones.
SEISMIC WAVE BY PLACE OF SPREADING
Based on the spreading, seismic waves can be divided into two parts, namely body wave that propagates into the body through the medium and surface waves where the amplitude is weakened when getting into the medium.
Several types of surface waves:
A. RAYLEIGH WAVE
Rayleigh waves are waves that propagate on the boundary surface only and can only travel on solid media and vibration direction opposite to the direction of propagation.
B. LOVE WAVE
Love waves are waves that propagate only in the boundary layer alone and move on a horizontal field.
C. WAVE TUBE
Wave tube is movement/flow of fluids along the well drilling. Fluid motion is caused by vibrations that propagate well wall in axial direction. Wave tube has three processes namely well wall contraction, to part well wall and the flow of fluid within the wellbore.
SEISMIC WAVES ACCORDING TO THE WAY PULSATE
Seismic waves according to the way pulsate,divided into two kinds :
1. Primary wave (longitudinal/compussional wave) primary wave is a wave that direction vibrotion pulsate in the direction of the wave. This wave has the greatest velocity of seismic waves to another.
2. Secondary wave (transversal/shear wave) secondary wave is the wave vibration direction perpendicular to the direction of wave propagation. This wave can only propagade in solid material only and has a wave speed is much smaller than the primary wave.
SEISMIC METHODS
Seismic methods ;one method of exploration is based on meansuring the responce of seismic waves (sound)
that is inserted into the ground and then in reflection or reflaction along different layers of soil or rock beun
daties. seismic source is generally a sledgehammer which in hit on the metal plate above the ground ,the great
mass of in drop or explosion of dynamite. Responses captured from soil measuerd whit a sensor called geophone, which measures the movement of the earth.
KINDS OF SEISMIC METHODS
There are two basic kinds of seismic methods are used, the seismic refraction and seismic reflection.
REFRACTION SEISMIC
Methods of measuring the refraction seismic waves the are reflection throunghout the geological formations
beneath the soil surface. Refraction events generally occur in ground water and the top of the rock bearing
rock formations. Graph of time came the first seismic waves at each geophone provides information on depth and location of these geological horizons. This information in then illustrated in a cross to indicate the depth of the water table and first layer of rock bearing rock.
REFLECTION SEISMIC
Seismic reflection method to measure the time if takes a sound impulse to go from the sound source,reflected
by the boundaries of geological formations , and retruned to the soil surface at a geophone .reflections of a geological horizon is similiar to an echo on a cliff or cliff face . Seismic reflection method widely used for petroleum exploration purposes. The datemination of earthquake source or the detection of soil structure.
Seismic reflection only observe reflected waves coming from the boundaries geologi formation .
This reflected wave can be diveded into several types of waves, namely, wave-p, wave-s ,wave stonely, and the waves love.
