(11C) Seismic Reflection Methods Applied to Engineering, Environmental & Groundwater

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An extract from Seismic Reflection Methods Applied to Engineering, Environmental, and Groundwater Problems, Kansas Geological Survey, KU (Lawrence, KS).

… determine the seismic velocity within the materials penetrated by the reflected seismic waves. The simplest procedure with good seismic-reflection data is to fit a hyperbola to the data using a least-squares approach. Table 1 shows a simple program for a HP11C or HP15C calculator that will calculate seismic velocity for such a case. The user simply inputs two or more time-distance pairs of numbers from a reflection on the field record or from the CDP gathers to calculate a seismic velocity. The program also calculates the reflection time for the zero-offset distance for the hyperbola …

Table 1.
Shown is a program that will run on either an HP 11C or HP 15C pocket calculator. The program (1) uses two or more time-distance pairs (distance treated as x and time as y) measured from a field seismogram as input data; (2) performs an hyperbolic least-squares fit of the data, assuming the time-distance pairs are picked from a true reflector; (3) calculates, stores, and displays zero-offset reflection time (TO), velocity (Vnmo), depth to reflecting interface (z), and correlation coefficient (r). The program assumes flat-lying as opposed to dipping reflectors …

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