Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan

Earth, Planets and Space

Table 2 List of friction experiments with ash. \(\phi _{\mathrm{b (Ramdom)}}\) and \(\phi _{\mathrm{b (Compacted)}}\) are the gas fractions in the ash before and after imposing a normal stress, respectively

Temperature (\({^{\circ }}\hbox {C}\))	Sieve (\(\upmu \hbox {m}\))	Thickness (mm)	\({\upphi }_{\mathrm{b(Random)}}\)	\({\upphi }_{\mathrm{b(Compacted)}}\)	\(\upsigma _{\mathrm{N}}\) (kPa)	Results
950	<53	2.0	0.65	0.46	26	Sintered
950	53–1000	3.2	0.46	0.43	26	Partially sintered
950	<53	2.3	0.65	0.54	5.1	Sintered
700	\(<53\)	2.0	0.65	0.47	26	Powder
700	53–1000	3.0	0.46	0.40	26	Powder
500	<53	2.1	0.65	0.48	26	Powder
500	53–1000	2.8	0.46	0.37	26	Powder
500	<53	2.3	0.65	0.52	5.1	Powder

The thickness is the final value of the measurement, and \(\sigma _{\mathrm{N}}\) is the desired normal stress to be imposed