Earthquake early detection capabilities of different types of future-generation gravity gradiometers.
This repository contains codes used in Shimoda et al. (2021).
The perturbation of the gravitational field is computed based on the half-space model
developed by Harms (2016).
Then each component of the gravity gradient is approximated numerically as the
finite difference of the gravity perturbations at two closely located points.
Gravity strain h(t) is obtained by integrating the gravity gradient twice over time.
We consider an optimal matched-filter detection procedure.
The optimal matched-filters are the pre-whitened signal templates h(t).
Both the signal templates and the recorded data s(t) = h(t) + n(t), where n(t) is detector noise,
are whitened by deconvolving them by the power spectrum of the detector noise.
The matched-filter output is obtained by correlating the whitened template with the whitened data. The signal-to-noise ratio (SNR) is defined as the ratio between the matched-filter output and the standard deviation of the matched-filter applied to noise alone.
- Shimoda, T., Juhel, K., Ampuero, J. P., Montagner, J. P., & Barsuglia, M. (2021). Early earthquake detection capabilities of different types of future-generation gravity gradiometers. Geophysical Journal International, 224(1), 533-542.
- Harms, J. (2016). Transient gravity perturbations from a double-couple in a homogeneous half-space. Geophysical Journal International, 205(2), 1153-1164.