The probability of total (Pt) and irreversible (Pir) losses of population

As the probability of building damage with varying levels (Table 2.5) as well as the probability of population losses (Table 2.6) are random variables, they should be assessed by the formulas:

Total losses of population, P t:

(2.11)

Irreversible (lethal) losses, Pir:

(2.12)

Sanitary losses, Ps:

(2.13)

where P ₃, P ₄, P ₅ are the probability of building damage with a corresponding level (Table 2.5)

Due to physical nature, these values P_t, P_ir, P_s represent the relative population loss in buildings, which are calculated as the ratio of the absolute losses N_a to total losses N:

. (2.14)

Then the absolute loss of population in buildings during an earthquake can be determined by the formula:

(2.15)

where the index i determines the type of losses (total, irreversible or health (sanitary)).

Nowadays the methods of statistical analysis of earthquakes are extensively developed.

These methods allow to make fluctuations maps (average frequency of earthquakes of a given energy class at considered point) and also recurrence graphics (dependence of the earthquake frequency oт magnitude).

Analysis of seismic data allow to predict areas where a future earthquake will arise and also allow to evaluate maximum intensity of earthquake. So, it is the basic aim of seismic zoning. Maps of seismic zoning provide background for any reconstruction project in seismic areas.

Compliance with the norms of aseismic stability can significantly reduce the devastating effects of earthquakes on buildings and structures.

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