Overview
Seismic refraction technique is an advanced geophysical method which is applied for routine investigation of subsurface ground conditions by using surface-sourced seismic waves. Data acquired with the help this technique on site is further computer processed and interpreted to attain models of the seismic velocity and layer thickness of the subsurface ground structure. We are one of best Seismic Refraction Survey Services in India.
Applications of Topographic Survey
- Measuring Bedrock Depth & Overburden Thickness
- Identifying Buried archeological sites
- Assessing subsurface geological hazards
- Investigate and locate Pipeline Routes Estimating the rippability before excavations
- Locating Geological Structures
- exploration of fossil fuel and other natural resources.
- Evaluating Sand & Gravel Deposits
The Technique
The seismic waves disseminate downward through the ground till the time they are reflected or refracted off subsurface layers. Refracted waves are identified by arrays of 24 or 48 geophones spaced at regular intervals of 1 – 10 meters, based on the required depth penetration of the survey. Sources are placed at each end of the geophone array to generate forward and reverse wave arrivals along with the array. Use of additional sources may intermediate positions for entirely covering at all geophone positions. If you are looking for Seismic Refraction Survey Services then you are at the right place.
Considerations in Seismic Refraction Survey
- The penetration depth in a seismic refraction survey is approximately 1/5th of the geophone spread length including offset shots. So if it is required to see 10m deep, you will need room to lay out at least 50m seismic spread, as measured from offset shot to offset shot.
- Any of the Geometrics seismographs can be utilized for seismic refraction. Up to24 channels or less, the SmartSeis ST is ideal. When using a laptop in the field works for you, the ES-3000 is a good option to the SmartSeis. For large-scale surveys, the Geode is recommended however For simplerippability, 12 channels will often suffice. For mapping the bedrock topography, a minimum of 24 channels are recommended. The detailed requirement needs more channels.
- A hammer-and-plate refraction survey is easily attained with two people. Longer lines and/or the use of explosives (which requires digging shot holes) generally need 3-4 people.
Advantages of Seismic Refraction Survey
- The survey is used to detect lateral and vertical variations in velocity
- Seismic surveys are useful in producing detailed images of the subsurface
- Used to measure stratigraphic units
- The Response of the seismic refraction survey depends on variations in rock density and elastic constants
- Sometimes, direct hydrocarbon detection is possible in Seismic refraction survey.
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