Earthquake Analysis over the Equatorial Region by Using the Critical Frequency Data and Geomagnetic Index

Abstract

This paper focuses on the variation of the ionosphere in the F2 layer over
the equatorial region during seismic event. The critical frequency of the
F2 layer, fcF2, shows that there is relationship between the variation of the
ionosphere and the occurrence of an earthquake. This fcF2 was obtained
from the ground-based ionosonde that has been stationed in Wireless and
Radio Science Centre, UTHM. Two statistical techniques, which are the
median and mean based techniques, were used to examine the possible
relationship between the occurrence of the earthquake with the variations
of the fcF2. For this research, two strong earthquakes phenomena occurred
in Indonesia were chosen. The results obtained shows that there is strong
relationship between the fcF2 and the occurrence of earthquake. Then, fitting
method from Matlab was applied to the respective fcF2 data some days before
and after the earthquake in order to obtain an analytical equation which
can be used as a precursor for the occurrence of an earthquake. However,
2 different earthquakes gave 2 different equations though. Other than
ionospheric disturbances, the earthquake also affects the Earth’s magnetic
field, which can be measured using geomagnetic index, Kp. However, the
Kp does not correlate very well with the variation of the fcF2 during an
earthquake.