Table 4.

Published Whole Rock and Glass Compositions for Lavas Emplaced During Etna's 1983 and 1991–93 Flank Eruptions^a

	Eruption
	1983		1991–93
	Whole Rock	Glass	Whole Rock	Glass
Source reference	1	2	3	4
Number of analyses	18	3	20	2
SiO2	46.8	50.4	47.9	51.8
TiO2	1.8	1.9	1.7	2.0
Al2O3	17.7	16.8	17.9	16.0
Fe2O3	3.6	–	3.3	4.6
FeO	6.8	10.4	7.0	6.5
MnO	0.2	0.2	0.2	0.2
MgO	5.7	3.2	5.4	3.0
CaO	10.7	7.6	10.0	6.9
Na2O	3.7	5.1	3.8	5.7
K2O	1.8	3.5	1.9	3.4
P2O5	0.5	–	0.4	–
Total	99.3	99.2	99.5	100.0
Viscosity at Tliquid [Bottinga and Weill, 1972]	17	27	20	19
Viscosity at Tliquid [Shaw, 1972]b	23	75	32	81
Viscosity at Tliquid (equation (2))	12	12	12	12
Viscosity at Terupt (method 1, Bottinga and Weill [1972])	417	662	491	466
Viscosity at Terupt (method 2, Shaw [1972])b	75	201	81	218
Viscosity at Terupt (method 3, equation (3))	305	305	305	305

^aAverages are given from the referenced sources. Fluid viscosities for each average composition are given at liquidus (T_liquid = 1160°C) and eruption temperatures (T_erupt = 1080°C). To assess the fluid viscosity at liquidus and upon eruption (subliquidus) temperature, we apply the same methods as followed in Table 2, with the input parameters set appropriate to Etna. Source references: 1, Armienti et al. [1984]; 2, Cristofolini et al [1987]; 3, Tonarini et al. [1995]; and 4, Armienti et al. [1994a].

^bCalculated using 0.4 wt % H₂O.