Earth, Planets and Space

Table 1 Observed velocity reduction and aspect ratio and fluid fraction of H₂O-filled pores in the lower crust.

From: Deep crustal structure around the Atotsugawa fault system, central Japan: A weak zone below the seismogenic zone and its role in earthquake generation

	Atotsugawa fault system		Niigata-Kobe Tectonic Zone
	Pyroxene amphibolite	Hornblende-pyroxene gabbro	Pyroxene amphibolite	Hornblende-pyroxene gabbro
dlnV_p	−0.10	−0.13	−0.058	−0.088
dlnV_s	−0.11	−0.12	−0.085	−0.092
dlnV_s/dlnV_p	1.10	0.92	1.44	1.05
Aspect ratio	0.04–0.05	∼0.2	0.01–0.02	0.05–0.06
Volume fraction	2–3%	∼10%	∼0.8%	3–4%

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