Assessment of Continuous Soil Radon Data for the Identification of Anomalous Changes During Moderate Earthquakes of the Garhwal Himalaya

Session: Alpine-Himalayan Alpide Shallow Earthquakes and the Current and the Future Hazard Assessments [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Continuous measurement of radon data is being carried out since year 2007 at multi-parametric geophysical observatory (MPGO), Ghuttu for the purpose of earthquake precursory research. To examine the effect of earthquakes on radon data, we carried out a statistical analysis and results are presented in this paper. For this study, we selected 20 cases of moderate sized and bigger earthquakes which occurred within 300 km of epicentral distance from MPGO, Ghuttu. On the basis of availability of data, the period of this study is chosen between 01 January 2009 and 31 December 2017. Past radon data of more than a decade period highlight a high effect of rainfall precipitation on the radon emanation mainly of soil concentration. It is found that out of total 20 earthquakes, 10 events are occurred in the monsoon season when data of radon is fluctuating mostly due to rainfall precipitation. Therefore, it is difficult to isolate the variations in radon data due to seismic events. However, 10 cases of earthquakes are occurred in pre and post-monsoon seasons when there is no effect of rainfall on the radon data. Hence, the fluctuations due to earthquakes can be identified in the radon data. Out of these 10 cases, anomalous variations in radon data are observed in 2 cases of earthquakes. To examine these anomalous variations, statistical analysis of radon data is carried out by calculating mean (m) and then obtaining deviation (σ) from mean values. Changes in the radon concentration are treated anomalous for values exceeding one and two standard deviations (m±σ and m±2σ) from the mean value for the selected duration. The observed results are explained in the light of dilatancy- diffusion model.

Presenting Author: Vaishali Shukla

Authors