The objective for this exercise is to estimate the frequency of the seismic data

Question

The objective for this exercise is to estimate the frequency of the seismic data in two windows and to calculate a seismic wavelength. You are given a portion of a seismic line with two enlarged windows. The steps are: 1. estimate the number of cycles over a short time window (e.g., 200 ms), 2. use an equation to convert from an 'apparent' to a dominant frequency 3. calculate the wavelength. The seismic data is on page 2. The equations you will need are: Fapparent- # cycle / time Interval Fdominant- (2* Fapparent)/ -Velocity/ Fdominant Window 1: 1.2 to 1.3 seconds use a velocity of 2000 m/s # cycles over 0.1 seconds Fapparent = #cycle/time interval = Fdominant (2" FapparentV A Velocity / Fdominant Window 2: 3.0 to 3.2 seconds use a velocity of 4000 m/s # cycles over 0.2 seconds- Fapparent #cycle/time interval- Fdominant(2" Fapparenty

Explanation / Answer

for window 1

cycles over 0.1 sec as visible are 2

Fapparent = cycles / time interval = 2/0.1 = 20 hz

Fdominant = 2 x Fapparent / pie = 12.74 hz

wavelength = velocity / Fdominant = 2000/12.74 = 159.98 m

window 2

cycles over 0.2 sec as visible are 2

Fapparent = cycles / time interval = 2/0.2 = 10 hz

Fdominant = 2 x Fapparent / pie = 6.37 hz

wavelength = velocity / Fdominant = 4000/6.37 = 627.94 m

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