lamb xmin dx np tmax fsamin vs den itype sfrq sdamp gfrq gdamp pol stab xmin = minimum geophone offset (m) dx = spacing of geophones (m) np = number of geophones tmax1 = maximum time for seismogram (s) fsamin= sample interval (seconds) vs = shear wave velocity (m/s) den = mass density (kg/m3) itype = type of traces output 1= ground displacement, step function source 2= ground particle velocity, step function source (or ground displacement, impulse source) 3= ground displacement, source wavelet=damped resonator 4= ground particle velocity, source wavelet=damped resonator 5= geophone displacement with source wavelet 6= geophone particle velocity with source wavelet (geophone voltage) 7= source wavelet displacement (at source) 8= source wavelet velocity (at source) 9= source wavelet geophone displacement (at source) 10= source wavelet geophone velocity (at source) sfrq = source wavelet high-cut frequency (hz) sdamp = source damping (fraction of critical, example .7) gfrq = geophone resonant frequency (hz) gdamp = geophone damping (fraction of critical, example .7) pol = polarity switch -1= SEG Sign Convention (up motion = negative = trough) 0= TEST MODE, for display of normalized solution, NO 1/R etc. +1= REVERSE SEG Sign Convention (up motion = positive = peak stab = stability factor, for derivative, moves pole off unit circle (not generally needed except for itype=8 (try stab=.16) since most other outputs have enough low-pass filtering) See function deriv for more
The code computes both vertical and horizontal motion (files lambv.seg and lambh.seg). The itype parameter selects the type of output signal.
The LAMB command corresponding to Figure 46 ( ).
lamb 1 1. 12 .5 .0001 100. 1700. 4 70 .2 10. .7 -1 .2
The above command computes the ground particle velocity for offsets 1 to 12 meters, .5 second record, sample interval of 0.1 msec, , density .
LAMB was re-run to compute the particle velocity of the geophone element (which corresponds to geophone voltage) by changing itype to 6. This is shown in Figure 47.
lamb 1 1. 12 .5 .0001 100. 1700. 6 70 .2 10. .7 -1 .2