Waveform inversion of the ultra-long-period seismic event associated with ground tilt motion during an eruption of Mount Kusatsu–Shirane, Japan, on January 23, 2018

Earth, Planets and Space

Table 2 Summary of the waveform inversion results

Candidate	(x, y, z) [m]	(θ, φ) [°]	E	N_max [10¹⁵ N m]	ΔV [10⁵ m³]	L [m]	W [m]	Δd [m]	Δt [s]
(a)	(− 2200, 600, 1000)	(15, 35)	0.419	18.58	28.81	2311	1618	0.770	5.7
(b)	(200, − 2600, 600)	(20, 60)	0.437	4.55	7.06	1446	1012	0.482	8.9
(c)	(600, − 3400, − 200)	(30, 85)	0.439	1.61	2.50	1023	716	0.341	9.7
(d)	(− 600, − 200, 1400)	(90, 90)	0.263	2.18	3.38	1131	792	0.377	8.4
(e)	(200, − 1400, 1000)	(25, 90)	0.259	6.73	10.44	1648	1153	0.549	11.2
(f)	(1000, − 3400, − 200)	(25, 95)	0.251	1.86	2.88	1073	751	0.358	12.2
(g)	(− 1000, − 600, 1000)	(90, 95)	0.486	2.44	3.79	1175	823	0.392	11.2
(h)	(− 1400, 1400, 1000)	(15, 0)	0.484	18.87	29.26	2323	1626	0.774	10.0
(i)	(− 1000, 200, 1800)	(15, 55)	0.395	18.10	28.07	2291	1604	0.764	14.6
(j)	(200, − 600, 1800)	(25, 45)	0.387	17.01	26.39	2245	1571	0.748	13.1
(k)	(− 1000, − 3000, − 1000)	(65, 65)	0.394	1.56	2.41	1011	708	0.337	15.3

Here, (x, y, z) indicates the source location; (θ, φ) indicates the crack orientation; E indicates the residual value; N_max indicates the maximum moment amplitude of the source time function; ΔV indicates the volume change; L, W, Δd indicate the length, width, and aperture change of the crack; and Δt indicates the time difference between the start of the eruption and the maximum amplitude of the source time function