Determining spatio-temporal characteristics of Coseismic Travelling
Ionospheric Disturbances (CTID) in near real-time
Abstract
Earthquakes are known to generate ionospheric disturbances that are
commonly referred to as co-seismic travelling ionospheric disturbances
(CTID). In this work, for the first time, we present a novel method that
enables to automatically detect CTID in ionospheric GNSS-data, and to
determine their spatio-temporal characteristics (velocity and azimuth of
propagation) in near-real time (NRT), i.e., less than 15 minutes after
an earthquake. The obtained instantaneous velocities allow us to
understand the evolution of CTID and to estimate the location of the
CTID source in NRT. Furthermore, also for the first time, we developed a
concept of real-time travel-time diagrams that aid to verify the
correlation with the source and to estimate additionally the propagation
speed of the observed CTID. We apply our methods to the Mw7.4 Sanriku
earthquake of 09/03/2011 and the Mw9.0 Tohoku earthquake of 11/03/2011,
and we make a NRT analysis of the dynamics of CTID driven by these
seismic events. We show that the best results are achieved with
high-rate 1Hz data. While the first tests are made on CTID, our method
is also applicable for detection and determining of spatio-temporal
characteristics of other travelling ionospheric disturbances that often
occur in the ionosphere driven by many geophysical phenomena.