The Amplitude-Distance Curve for Short Period Teleseismic P-Waves

Abstract

An amplitude-distance curve has been computed for short period P waves in the range A=30"-102" (and h=O) using the amplitudes of explosion signals only. Effects of source asymmetry can thus be discounted and the problem of deciding what amplitude to measure is reduced because the maximum amplitude of explosion signals always occurs in the first few cycles. To increase the consistency of the measurements all the amplitudes have been measured by the same person.Assuming the effect of distance is constant over a series of discrete intervals of distance, the amplitude-distance curve with its confidence limits has been estimated by least squares using data from 65 stations which recorded some or all of the explosions fired at six sites. The most striking features of the curve are: (1) a sharp maximum at about A = 35", (2) a minimum followed by a sharp increase at A = 75", and (3) a sharp minimum at A =93". Over the remainder of its length the curve is similar to the Gutenberg and Richter curve. Station magnitude corrections have also been estimated.

Comparison of least squares analyses of long and short period P wave amplitudes

“…Nevertheless it is not certain that this is the case. The decrease in amplitude predicted by ray theory is caused by defocusing in the 0" layer, and was also calculated by Carpenter (1966) from the Jeffreys-Bullen travel times. The effect is not pronounced below about 90", and it is possible that beyond this point both defocusing and diffraction effects could be present.…”

Amplitude Variations with Azimuth and Distance of Short Period P Waves Recorded at some Iberian Stations

“…4(d)) and it also exhibits a wide minimum between 50" and 70", though somewhat shifted in respect to that of our curve. The level of the relations ( A -A ) by Cleary (1967) and Carpenter et al (1967), (obtained by using short period P waves) is some 0.3 units of magnitude larger than ours in the range 50"-75" (Fig. 4(e) and (f), respectively).…”

UK 1-D regional velocity models by analysis of variance of P-wave travel times from local earthquakes

“…To analyse the data I follow Carpenter et al (1967) and make the assumption that if T ijk is the measured P-wave travel time from the source of earthquake i to station j whose epicentral distance lies in the k-th distance range then…”

“…The technique was originally applied by Carpenter et al (1967) to the amplitude attenuation with distance of teleseismic P-waves, but the method is equally applicable to the variation with distance of seismic travel-times. In contrast to most inversion procedures, a good a priori starting model is not required.…”

“…The technique was originally devised by Fisher (1925) and has been further developed since then by Scheffé (1959), Kempthorne (1952), Brownlee (1965) and others. Carpenter et al (1967) used the AoV method to determine amplitude variation with distance, and source size and station attenuation, from recorded amplitudes of teleseismic P-waves. In this paper Carpenter et al's (1967) technique is applied to local P-wave travel times.…”