We assume that the depth of the lower limit of the fault plane of each fault is same as the bottom depth of the seismogenic zone.
For flow parallel to the plane of the fault our analysis shows that the fault zone is dominated by broad areas of low to moderate permeability, interspersed with a number of spatially discrete, high-permeability flow paths.
Based on these results, seismic slip during the mainshock is inferred to have occurred on Faults 1 through 4. Therefore, these best-fit planes of Faults 1 through 4 can be defined as the "mainshock fault".
These faults have a displacement vector of 1/2〈001〉 lying in the plane of the fault.
The updated finite-fault estimate converged to a fault plane along the Futagawa fault segment, which was the conjugate fault plane of the previous fault model estimates.
In Jagla's model, the "forest" is the plane of a fault cutting through Earth's crust, divided into a 10,000-by-10,000 grid.
The estimated fault was, however, an auxiliary fault plane of the Hinagu fault (Additional file 3: Figure S3).
The strike-slip fault planes of Hinagu fault zone are noticeable also in the vertical cross sections in Fig. 9 showing hypocenters of the Kumamoto earthquakes as inferred by Kato et al. (2016).
The quantities (2a) and (2b) represent the length and width of each fault plane estimated in "Estimation of fault planes" section.
