The reflection is
the energy or wave from an earthquake that has been returned (reflected) from an boundary between two different materials within the earth
, just as a mirror reflects light.
What is the difference between reflection and refraction in earthquakes?
In seismic reflection method the waves travel downward initially and are reflected at some point back to the surface, the overall path being essentially vertical. … Whereas, in seismic refraction method, principal portion of the wave-path is along the interface between the two layers and hence
approximately horizontal
.
What is seismic reflection and refraction?
A seismic refraction or seismic reflection line is
a set of seismographs usually lined up along the earth’s surface to record seismic waves generated by an explosion
for the purpose of recording reflections and refractions of these waves from velocity discontinuities within the earth.
How does seismic reflection work?
The general principle of seismic reflection is
to send elastic waves
(using an energy source such as dynamite explosion or Vibroseis) into the Earth, where each layer within the Earth reflects a portion of the wave’s energy back and allows the rest to refract through.
Why do earthquake waves refract?
When a wave encounters a change in material properties (seismic velocities and or density) its energy is split into reflected and refracted
waves. … Likewise, when an S-wave interacts with a boundary in rock properties, it too generates reflected and refracted P- and S-waves.
What are P and S waves?
In P or compressional waves, the vibration of the rock is in the direction of propagation. P waves travel fastest and are the first to arrive from the earthquake. In S or
shear waves, rock oscillates perpendicular to the direction of wave propagation
.
Where do very deep earthquakes occur?
The deepest earthquakes occur
within the core of subducting slabs – oceanic plates
that descend into the Earth’s mantle from convergent plate boundaries, where a dense oceanic plate collides with a less dense continental plate and the former sinks beneath the latter.
How do geophones work?
A geophone works
using a coil of wire wrapped around a mass, suspended by a spring over a magnet
. As the mass moves, the magnet moves the electrons through the wire coil producing an electrical signal (voltage). Seismographs record this voltage signal.
What is the difference between 2D and 3D seismic survey?
In two-dimensional (2D)
reflection
seismic surveying both the sound source and the sound detectors (numbering up to a hundred or more per shot) are moved along a straight line. … 3D seismic programs are generally a uniform and evenly spaced grid of lines.
What is seismic method in geophysics?
Seismic methods are the
most commonly conducted geophysical surveys for engineering investigations
. Seismic refraction provides engineers and geologists with the most basic of geologic data via simple procedures with common equipment. … These vibrations are seismic waves.
What is seismic used for?
Seismic surveys use reflected sound waves to produce a “CAT scan” of the Earth’s subsurface. Seismic surveys can help locate ground water, are used to investigate locations for landfills, and characterize how an area will shake during an earthquake, but they are primarily used for
oil and gas exploration
.
Who invented seismic reflection?
The first reflection patent, US Patent no. 1,843,725, was filed on 1 May 1929 by
John Clarence Karcher
… almost 6 months after the discovery well was completed.
What is reflection configuration?
Reflection configuration patterns can be divided into three groups:
Parallel
—including subparallel and divergent. Discontinuous. Prograding—caused by lateral accretion of strata.
What happens to S and P-waves as they travel inside Earth?
S waves cannot pass through the liquid outer core, but P waves can.
The waves are refracted as they travel
through the Earth due to a change in density of the medium. When the waves cross the boundary between two different layers, there is a sudden change in direction due to refraction. …
What are the 10 effects of earthquake?
The primary effects of earthquakes are
ground shaking, ground rupture, landslides, tsunamis, and liquefaction
. Fires are probably the single most important secondary effect of earthquakes.
How do seismic waves behave?
Seismic waves travel
a curving path through the earth due to changes in composition, pressure, and temperature within the layers of the Earth
. Seismic waves travel at different speeds through different materials. In this 2-layer model two wave fronts leave an impact at the same time but the lower layer is faster.
