Seismic-Refraction Method 2. This method consists of the generation of elastic waves on a given point of the surface. Seismic methods Marine seismic measuring methods. Seismic refraction traverses (seismic lines) are performed using an array of seismographs or geophones and an energy source.. Geophysical methods are used in geotechnical investigations to evaluate a site's behavior in a seismic event. This is on account of the fact that velocity of sound waves is different in different media. • Measurement of seismic-wave travel time is one of the most common geophysical method. The refraction method is widely used for the characterization of groundwater depth. This reduces the cost involved in subsurface investigation. Introduction to Seismic Method: 2. Seismic refraction provides engineers and geologists with the most basic of geologic data via simple procedures with common equipment. In the former, resistance to flow of a seismic wave through soil is measured; in the latter, resistance of soil to movement of an electrical current is determined. THE USE OF SEISMIC REFRACTION METHOD IN SLOPE FAILURE INVESTIGATION 205 landslide or slope failure, the soil properties of the disturbed failure material are in general lower in terms of shear strength, rigidity, bulk density and porosity as compared to the original … seismic reflection). 4. Emujakporue Department of Physics, University of Port Harcourt, Nigeria. The same field data can be used to draw different inferences. This method uses a controlled energy source (e.g., an airgun) at given locations (shot points) to introduce a seismic signal into the subsurface. ReMi is a seismic surface wave testing method that is used to aid in seismic site classifications. Seismic refraction maps contrasts in seismic velocity – the speed at which seismic energy travels through soil and rock. Seismic methods can provide valuable information of the subsurface, such as the seismic velocity structure of the geology (e.g. This technique does, however, have other applications on a smaller scale, such as for civil engineering project site investigation. The seismic refraction method utilizes the refraction of seismic waves on geologic layers and rock/soil units in order to characterize the subsurface geologic conditions and geologic structure. ReMi method uses ambient noise and surface waves to generate a detailed vertical shear wave velocity (V s) profile of soil stratums up to 300 feet in depth. Seismic methods have long been recognized as an effective tool for studying the shallow subsurface for a variety of applications, such as engineering problems, geotechnical evaluations, environmental studies, hydrogeological investigations, seismic risk assessment, archeology, etc. Indirect exploration methods include geophysical investigation methods such as sounding, and seismic reflection and refraction. 5. Seismic Refraction and Electrical Resistivity Investigation of Building Failure: A Case Study 1Julius O. Fatoba, 1 ... Methods of testing soils for engineering parameters were conducted in accordance with BS 1377 (1990) for all soil samples collected. There are a number of methods used to determine a site's shear wave velocity: Crosshole method; Downhole method (with a seismic CPT or a substitute device) 5.1.1 This guide summarizes the equipment, field procedures, and interpretation methods used for the determination of the depth, thickness and the seismic velocity of subsurface soil and rock or engineered materials, using the seismic refraction method. Responses of a shock wave eminating from a source are picked up by geophone at known distance. The depth of rock underlying the soil or depth of … Geophysical site investigation methods are simple, quick and physical in nature, making them environmentally friendly and cheap. Fig. The seismic reflection geophysical method was employed for the investigation. Theory Seismic investigation depends on the propagation of waves in an elastic medium. The methods are: 1. Introduction to Seismic Method 1. Marine seismic measuring methods belong to the main components in marine research for the investigation of the marine resource potential and hazard assessment, for example by earth slides, tsunamis or the release of greenhouse gas. refraction seismology. By measuring a soil's shear wave velocity, the dynamic response of that soil can be estimated. While the active method using an artificial seismic sou rce, like a sledgehammer, can often achieve the goal of Vs estimation down to a few tens of meters (for example, Photograph of a seismic refraction survey Seismic refraction tomogram of a salt diapir in central Utah. Seismic refraction survey also gives the various layers in the subsurface by using the velocities of the seismic waves in the subsurface thereby helping in reducing the number of borehole that are required for the subsurface investigation at a site. 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