ИСТИНА

The analysis of the catalog of earthquakes of the Azores is carried out. It is assumed that the manufactured noise in this area is minimal, so this is a good area to test the noise hypothesis of the origin of diurnal and seasonal variations. The catalog from the resource of stations in the international seismological center http://isc-mirror.iris.washington.edu, as well as data from the Iris website, were used. Based on data from IRIS stations, a selective analysis of the properties of noise on the recording network was carried out. Also analyzed the data of meteorological observations. Based on the data from the earthquake catalog, the mean daily and mean seasonal variations have been analyzed and the spectra of the time series of seismicity have been estimated. The extrema of the spectra were established for periods of about a day and a year. No similarity was found between the variations of the indicated series and seismicity for periods of about a year and a day. It was found that, depending on the strength of the event, the network of stations registering it could be significantly different. From the analysis of the entire set of data, no reliable confirmation was found for the noise hypothesis of diurnal seismicity variations in this area. Therefore, the reasons for the seasonal and daily frequency may also be different. As a result, atypical graphs of magnitude frequency can be observed. Seasonal and daily frequency are considered. Interpreting these effects is made more difficult by these repeatability plots. Due to the great remoteness of the area and the small presence of industry, diurnal and seasonal variations in seismicity may have, possibly partially, natural causes.