A Statistical approach to study the propagation conditions in the Atmosphere prior to some seismic events.

Abstract:

In the present paper, a statistical approach is applied to the derived Refractivity Gradient data, from COSMIC-FORMOSAT mission to understand its long term variation and to identify the anomalous behavior before, on and after two Earthquakes. The data obtained for epicenter region of two Earthquakes that had occurred on 11 August 2012 (38.31° N, 46.86° E) and on16 April 2013 in Iran (28.10°N, 62.05°E) are considered here for the study. Four different statistical approaches: Cumulative Distribution Function, β₀ Parameter, Chi-Square Variance Test, and inter quartile range (IQR) are applied to know the statistical behavior of the Refractivity Gradient and thus the propagation conditions in the atmosphere. It is seen that atmospheric refractivity gets modified from 8 to 4 days prior to the earthquake around the epicenter exceeding the confidence level, β₀ parameter also increases for the month of occurrence of the Earthquake indicating anomalous propagation conditions.