Dip angles of active faults from the surface to the seismogenic zone inferred from a 2D numerical analysis of visco-elasto-plastic models: a case study for the Osaka Plain

Earth, Planets and Space

Table 1 Comparison between the geological observations and model results

Model	Sedimentary layer thickness (m)						Sedimentation rate (m/kyr)		Basement depth (m)			Vertical displacement rate (m/kyr)
	Lower Tanaka F.			Upper Tanaka F. + Namba F.			Lower Tanaka F.		Basement depth (m)			Vertical displacement rate (m/kyr)
	OD-1*	Um*	OD-3*	OD-1	Um	OD-3	Um	OD-3	OD-1	Um	OD-3	Uemachi fault	Ikoma fault
Geological observations
	400¹	250¹	450¹	250¹	0¹	250¹	0.3–0.5¹	0.5–0.8¹	~ 1500¹	800¹	~ 1600²	0.3¹–0.4³	0.5–1⁴
Linear Uemachi case (dip angle of 40°, Fig. 10)
Mean** (n = 3)	398 ± 0	339 ± 8	418 ± 17	262 ± 0	212 ± 17	280 ± 27	0.51 ± 0.01	0.62 ± 0.02	1553 ± 11	1184 ± 32	1582 ± 56	0.17 ± 0.01	0.76 ± 0.04
Linear Uemachi case (dip angle of 30°, Fig. 11a)
Mean (n = 3)	398 ± 0	285 ± 12	341 ± 12	262 ± 0	157 ± 11	207 ± 20	0.43 ± 0.02	0.51 ± 0.02	1552 ± 11	998 ± 20	1364 ± 36	0.27 ± 0.02	0.71 ± 0.08
Curved Uemachi case (Fig. 11b)
Mean (n = 3)	398 ± 0	247 ± 11	357 ± 9	262 ± 0	138 ± 7	227 ± 7	0.37 ± 0.02	0.53 ± 0.01	1552 ± 11	850 ± 6	1481 ± 12	0.30 ± 0.01	0.74 ± 0.04
More curved Uemachi case (Fig. 11c)
Mean (n = 3)	398 ± 0	325 ± 10	428 ± 11	262 ± 0	183 ± 11	266 ± 17	0.49 ± 0.01	0.64 ± 0.02	1553 ± 11	1116 ± 26	1699 ± 39	0.19 ± 0.01	0.76 ± 0.12
Sato et al. (2009) model (Fig. 12b)
Mean (n = 3)	398 ± 0	173 ± 34	329 ± 16	262 ± 0	65 ± 28	173 ± 28	0.26 ± 0.05	0.49 ± 0.02	1552 ± 11	727 ± 71	1404 ± 49	0.40 ± 0.05	0.71 ± 0.07

^* OD-1, Um and OD-3 represent the location of the OD-1, OD-9 and OD-3 core sites, respectively
^** Mean represents arithmetic mean (± 1σ standard deviation) derived from the simulation results with different random seeds
¹Uchiyama et al. (2001)
² Osaka Prefecture (2004)
³Headquarters for Earthquake Research Promotion of MEXT (2001)
⁴Shimokawa et al. (1997)