Figure 5 | Scientific Reports

Figure 5

From: Precursory worldwide signatures of earthquake occurrences on Swarm satellite data

Figure 5

Worldwide Statistical Correlation (WSC) in terms of a superposed epoch approach applied to electron density with threshold kt = 3.0 (a) or Y magnetic field with threshold kt = 2.5 (b) considering the DbA around the EQ epicentre and different ranges of magnitude values. Please note that the investigated time interval is 500 days (versus 90 days before and 30 days after in the previous analyses) before the EQ occurrences and each temporal bin is of 10 days (versus 2.4 days of previous analyses). Only the closest spatial band to the EQ epicentre is shown; for convenience colour palettes are not shown, although blue stands for the lowest density (close to zero) and brown for the largest density (that differs from case to case). Red ovals indicate the larger concentrations considered for the Rikitake law; yellow ovals are not taken into account for the reason given in the main text. (c) shows the Rikitake law for electron density Ne (black circles and thin fitting solid line) and Y magnetic field (empty circles and thin fitting dash line). Also the corresponding a and b coefficients are given, together with the upper and lower bounds of the Rikitake law for ground magnetic precursors45.

Back to article page