Seismic Refraction Investigation at a Radioactive Waste Disposal Site

Abstract

The earth is characterized by many layers, each with different physical properties. When sound waves travel through the earth encounter a change in the physical properties of the material in which they travel, they will either reflect back to the surface or penetrate deeper into the earth; where they may again be reflected at another interface. At a geological interface some seismic energy will react when it encounters a subsurface layer. This physical property is closely associated with the density of a layer. A site earmarked for a radioactive waste disposal facility was assessed by means of seismic refraction survey for purposes of revealing the sub-surface information and to ascertain whether or not the site is 'competent' to host a radioactive waste disposal facility. The processed seismic information obtained indicates discontinuity in the rock-formation at certain points on the survey lines. These points have been mapped as the weak zones at stations 25 meters and 65 meters along line 2 and at stations 25 meters, 50 meters and 100 meters along line 3-spread 1.

Soil geotechnical characteristics for seismic risk mitigation at the southern extension of Marsa Alam city, Egypt

“…The seismic refraction approach depends on the refraction of seismic waves at the borders between subsurface strata of various velocities. Dawood et al (2012) mentioned that when the seismic survey conduct in a specific area the propagated waves encounter the border between two various rock units, some of the waves are reflected and the others refracted. The law that defines the principles of the refraction of incident rays is Snell's Law, which relates the incidence and refraction angles to the seismic wave's velocities in the two different units.…”

“…Where υ 1 and υ 2 are the velocity of the first and second layer, respectively. Milsom (2003) declared that the refracted waves will move to the border if ν 2 is larger than ν 1 , and if sin i equals ν 1 /ν 2 , this incident angle called critical angle at which the angle of the incident waves is 90°, this permits to refracted waves to move along the border at the unit which characterised by higher velocity v 2 (Dawood et al 2012). The term crossover distance X c will appear when both the refracted and direct waves arrive simultaneously.…”

Soil and Subsurface Sediment Microzonation Using with Seismic Refraction Tomography for Site Assessment (Case Study: IKIA Airport, Iran)

“…The seismic refraction method uses very similar equipment to seismic reflection, typically utilizing geophones in an array, and a seismic source (shot). When a seismic wave encounters an interface between two different rock types, some of the energy is reflected and the remainder continues on its way at a different angle, i.e., it is refracted [28] [35].…”

“…The law of reflection is very simple; the angle of reflection is equal to the angle of incidence. Refraction on the other hand is governed by Snell's law, which relates the angles of incidence and refraction to the seismic velocities in the two media as follows [28]:…”

“…In this study, the seismic refraction method was used for addressing the Robat-Karim fault beneath the Imam Khomeini International Airport (IKIA) and its surrounding. The seismic refraction method has been used in various and numerous studies [28]- [31]. Such as this investigation, the seismic refraction technique has been used in several cases for evaluation, finding and detecting the faults and fracture zones in underground environments [32]- [34].…”