Study of pre-seismic thoron anomaly using empirical mode decomposition based Hilbert–Huang transform at Indo-Burman subduction region

Estimation of 238U and 232Th in soil and water of prominent fault region of Mizoram

“…This observation ignites opti-mism among researchers to predict earthquakes by monitoring radon anomaly and soon it becomes a global phenomenon that continues till dates [5-11, 37-39, 47-53]. Uncertainty and inaccuracy in prediction remained the main issue of present-day researchers, which is very well visible from some recent reports [37][38][39][47][48][49][50][51][52][53]. Chowdhury et al [38] and Sahoo et al [39] from the east and north India, respectively observed unpredicted earthquakes and false radon anomaly peaks, though they observed a positive correlation between them.…”

“…Although extensive work has been done; radon monitoring and especially estimating its parent nuclei still has uncertainties reflected as well in the above recent reports [27][28][29][30][31][32][33][34][35][36]. The main problem is that the radon exhalation process was influenced by several external factors such as physicochemical features of the soil (such as grain size, density, porosity, permeability etc), geophysical factors (morphology and movement of groundwater and nature of aquifers) and meteorological factors (temperature, pressure, humidity, rainfall and wind speed) [16,17,[37][38][39]. Without preventing or removing the external influence, the obtained result may be ambiguous and will lead to the wrong estimation.…”

“…To handle the meteorological problem, the meteorological data were as well measured in-situ online along with the radon data. A ZnS(Ag) alpha scintillation counter named SMARTRnDuo developed and calibrated by Bhabha Atomic Research Centre, Mumbai (India) was used for measuring the radon and thoron data [16,17,37]. It was equipped with a device for recording temperature, humidity and pressure data automatically.…”

“…Since the isotope pair data were generated in an active fault they were also suitable for identifying geophysical phenomena of the region like seismic activity. The first officially recorded radon anomaly before seismic activity was in 1966 before the Tashkent earthquake in Russia [37]. This observation ignites opti-mism among researchers to predict earthquakes by monitoring radon anomaly and soon it becomes a global phenomenon that continues till dates [5-11, 37-39, 47-53].…”