Abstract <p>The Moscow State University (MSU) Extensive Air Shower (EAS) array is used to study the temporal distributions of particles in extensive air showers (EASes) with energies greater than 10¹⁴ eV. Delayed particles are registered in ~3.5% of all EASes. The flash observed in the frequency of their registration from 1986 to 1990 with a maximum in 1987 is discussed. The fine structure of flash decay consists of a series of bursts of quasi-periodic damped oscillations with periods of ∼4 days and durations of ∼32.5 days. The frequency of EAS registration does not change within the limits of statistical error.</p>