Site-dependent organization structure of seismic microtremors

• The time dynamics of gravity signal measured in Sheki, Azerbaijan, was analysed.
• Two main periodicities (12 hours and 24 hours) in gravity signal were identified.
• Antipersistent structure of the gravity signal was identified at any timescale.
• The multifractality of gravity signal depends on the long-range correlations.

The time dynamics of seismic microtremors recorded in several sites in Chisinau City (Moldova) are analysed by means of the informational approaches of the Fisher Information Measure (FIM) and the Shannon entropy. The sites show different soil characteristics. One of the investigated sites, Minar Calcar (MC), is located on hard rock, while the others on soft soil. Our analysis has shown that MC, which is very different from the other sites, is featured by the highest FIM and the lowest Shannon entropy. This indicates that the properties of order and organization of seismic microtremor time series depend on the soil characteristics of the sites, suggesting a higher organization structure and lower disorder in those microtremors recorded in hard rock sites with respect to those recorded in soft soil sites.