Lahar characteristics as a function of triggering mechanism at a seasonally snow-clad volcano: contrasting lahars following the 2014 phreatic eruption of Ontake Volcano, Japan

Kataoka, Kyoko S.; Matsumoto, Takane; Saito, Takeshi; Kawashima, Katsuhisa; Nagahashi, Yoshitaka; Iyobe, Tsutomu; Sasaki, Akihiko; Suzuki, Keisuke

doi:10.1186/s40623-018-0873-x

Earth, Planets and Space

Table 4 Results of XRF (bulk chemistry) of ashfall, rain-triggered lahar and ROS-triggered lahar deposits, and pre-eruptive fluvial deposits

From: Lahar characteristics as a function of triggering mechanism at a seasonally snow-clad volcano: contrasting lahars following the 2014 phreatic eruption of Ontake Volcano, Japan

Lithology	Sample name	SiO₂ (wt%)	TiO₂	Al₂O₃	Fe₂O ^a₃	MnO	MgO	CaO	Na₂O	K₂O	P₂O₅	SO ^b₃	Others	Total
FP method for sediments analyzed by Rigaku RIX 1000
September 2014 primary deposits
Ashfall	On-1	57.03	0.87	16.46	5.62	0.03	0.53	1.37	1.11	2.12	0.30	14.29	0.25	100.00
Ash could deposits	On-44	56.13	0.61	14.65	5.31	0.04	1.12	4.18	1.29	1.90	0.36	14.23	0.19	100.00
October 2014 rain-triggered lahar (Cohesive debris flow) deposits
Muddy	On-2	56.77	0.95	15.24	6.12	0.05	0.91	3.16	1.07	2.27	0.37	12.90	0.19	100.00
Muddy	On-3	55.40	1.03	13.68	7.12	0.06	0.89	3.62	1.72	2.07	0.33	13.91	0.18	100.00
Muddy	On-4	58.66	0.93	15.45	5.49	0.05	0.95	3.20	1.17	2.21	0.36	11.34	0.18	100.00
Muddy	On-5	59.62	0.97	13.38	6.24	0.04	0.64	2.95	1.11	1.92	0.29	12.66	0.18	100.00
Muddy	On-6	57.80	1.07	14.46	6.80	0.08	1.20	3.65	1.94	2.16	0.32	10.34	0.18	100.00
Muddy	On-13	57.89	0.88	15.36	5.94	0.06	0.99	3.43	1.38	2.31	0.29	11.26	0.21	100.00
Muddy	On-18	58.16	0.96	15.45	5.43	0.05	0.88	2.68	1.49	2.25	0.36	12.11	0.18	100.00
Muddy	On-34	57.57	0.87	15.98	5.73	0.05	0.97	3.15	1.47	2.20	0.36	11.49	0.16	100.00
Muddy	On-45	56.90	0.80	15.50	5.51	0.06	1.03	3.33	1.37	2.10	0.32	12.79	0.28	100.00
April 2015 rain-on-snow-triggered lahar deposits
Sandy	On-16	61.05	1.00	15.66	5.90	0.09	1.10	4.29	1.82	2.41	0.29	6.21	0.18	100.00
Sand-gravel	On-19	65.65	0.91	15.53	4.55	0.07	0.67	3.32	1.76	2.73	0.33	4.31	0.17	100.00
Sandy	On-26	64.92	0.64	16.67	4.72	0.11	1.00	5.05	2.89	2.95	0.29	0.62	0.14	100.00
Sand-gravel	On-51	60.26	1.06	14.80	5.85	0.06	1.00	3.20	2.07	2.58	0.28	8.65	0.19	100.00
April 2015 rain-on-snow-triggered lahar deposits (mud drape)
Muddy	On-21	57.75	0.77	18.31	5.81	0.03	1.09	1.58	1.10	2.20	0.53	10.69	0.15	100.00
Pre-eruptive fluvial deposits
Sandy	On-7	61.90	1.14	15.80	6.85	0.14	1.31	5.25	2.44	2.60	0.36	2.08	0.15	100.00
Sandy	On-11	63.89	0.97	16.07	5.87	0.11	1.08	4.99	2.28	2.63	0.34	1.58	0.20	100.00
Sandy	On-17	65.68	0.78	15.45	5.27	0.11	0.97	4.15	2.38	3.03	0.37	1.65	0.16	100.00
Sandy	On-22	66.35	0.67	15.68	4.73	0.10	0.98	4.71	2.97	3.14	0.27	0.27	0.14	100.00
Sand-gravel	On-33	66.57	0.99	15.34	4.44	0.08	0.90	3.80	1.82	2.75	0.28	2.83	0.20	100.00
Sand-gravel	On-43	64.38	1.01	15.67	4.90	0.08	0.99	4.01	1.65	2.63	0.36	4.11	0.21	100.00
Shirakawa deposits
Muddy	On-23	61.81	0.70	15.06	5.18	0.05	0.98	2.97	1.55	2.34	0.27	8.94	0.16	100.00
Sandy	On-24	60.73	0.78	16.08	5.36	0.07	0.99	3.92	2.38	2.45	0.43	6.66	0.16	100.00

Sample name	As (ppm)	Ba	Co	Cr	Cu	Nb	Ni	Pb	Sr	V	Zn	Total
Calibration method for sediments analyzed by Rigaku RIX 2000
September 2014 primary deposits
On-1	24	475	16	37	13	8	10	13	528	198	72	1654
On-44	15	495	13	36	15	8	8	16	551	127	100	1652
October 2014 rain-triggered lahar (Cohesive debris flow) deposits
On-2	16	462	17	36	12	8	10	10	540	200	73	1636
On-3	15	487	16	39	13	9	8	12	546	195	85	1685
On-4	12	457	14	62	12	8	13	12	545	190	72	1659
On-5	16	425	17	36	13	9	11	12	531	184	75	1591
On-6	14	482	17	36	11	10	10	10	557	202	83	1690
On-13	14	479	15	34	12	9	9	11	533	182	70	1627
On-18	13	463	13	34	10	9	7	12	532	193	55	1614
On-34	15	456	12	33	12	9	8	13	547	188	66	1635
On-45	16	473	15	35	14	9	12	11	546	187	78	1645
April 2015 rain-on-snow-triggered lahar deposits
On-16	10	468	13	34	10	10	11	11	590	185	75	1669
On-19	8	529	8	28	9	9	8	13	529	165	61	1659
On-26	3	554	9	27	8	9	8	13	603	119	77	1697
On-51	12	488	12	34	12	9	10	11	550	202	59	1673
April 2015 rain-on-snow-triggered lahar deposits (mud drape)
On-21	21	508	13	33	13	8	8	16	572	195	68	1727
Pre-eruptive fluvial deposits
On-7	6	489	13	35	9	11	11	10	564	213	96	1732
On-11	5	511	10	28	9	9	9	12	597	182	77	1712
On-17	5	566	9	28	7	10	10	12	533	155	75	1704
On-22	3	591	11	26	7	11	10	14	546	122	82	1731
On-33	7	520	9	30	6	10	8	11	507	188	65	1663
On-43	8	496	10	31	9	10	10	10	546	200	67	1668
Shirakawa deposits
On-23	10	503	8	27	9	8	6	13	527	110	54	1529
On-24	9	519	9	29	11	8	8	13	579	143	66	1655

^aTotal iron oxide as Fe₂O₃; ^btotal sulfur as SO₃

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