Numerical simulations to explain the coseismic electromagnetic signals: a case study for a M5.4 aftershock of the 2016 Kumamoto earthquake

Earth, Planets and Space

Table 1 Properties of the used water-saturated porous materials

Properties	p_w1	p_w2
Porosity ϕ (%)	15	45
Solid density ρ_s (10³ kg/m³)	2.75	2.7
Static permeability k₀ (10⁻¹² m²)	1.0	10.0
Solid bulk modulus K_s (GPa)	60.0	8.0
Frame bulk modulus K_fr (GPa)	34.0	5.0
Shear modulus G (GPa)	22.0	2.5
Fluid viscosity η (10⁻³ Pa s)	0.2	0.4
Salinity C₀ (10⁻³ mol/L)	5	2
Tortuosity α_∞	2	1.5
Bulk conductivity σ (S/m)	0.042	0.017
Fast P wave quality factor Q_pf	320	160
S wave quality factor Q_s	240	120

Parameters such as fluid density ρ_f = 1.0 × 10³ kg/m³, fluid bulk modulus K_f = 2.2 GPa, fluid permittivity κ_f = 80 and solid permittivity κ_s = 4 are used for all water-saturated porous materials