Time-series analysis of terrestrial impact crater records

A database of impact craters becomes available with more accurate and more precise age estimates due to a new decay constant. This motivates us to revisit the periodicity hypothesis for the terrestrial impact cratering rate, using the new data set. We present a new way to analyze the impact cratering rate as an oscillator in the time domain. This technique aims to produce an accurate frequency of an oscillator whose phase is modulated, and to reveal the slowly varying phase function. Having applied the technique to recent cratering records, which are grouped into 6 subsamples by criteria on the age and diameter of impact craters, we found the presence of a ∼ 26 Myr periodicity in the impact cratering rate over the last ∼ 250 Myr. Such a periodicity can be found consistently in subsamples regardless of the lower limit of the diameter up to D ∼ 35km. We have also calculated the period of the impact cratering rate using the Lomb-Scargle periodogram method. The Lomb-Scargle periodogram method yields slightly more scattered periods, implying that our technique is more robust and stable than the Lomb-Scargle periodogram analysis. As reproducing f (1), we found that its typical magnitude of ε f(t) is much smaller than that of the frequency. Therefore, we conclude that the impact cratering rate may be regarded as unimodal.