Appendix A
A volume calculation model (Kereszturi et al., 2013) was applied to the Al-Du’aythah cones, where
erosion is relatively low to moderate, no products are covered by younger eruptions, and different
volcanic units can be defined. These units are 1) Stratified, country rock-rich deposits, 2) Massive
scoriaceous deposits, and 3) Lava flows (Fig. 8). Diatremes were not considered. Percentages of
juvenile rock and inter- and intra-particle void spaces used for calculations are shown in Table A1
(see Kereszturi et al., 2013 for details). Due to burial of the initial phreatomagmatic phase of cones
2-4, a correction was applied. The corrected phreatomagmatic bulk volumes were derived as: Vtuff corr
= Vtuff + (Aburied×5) where the Vtuff is the volume of the exposed tuff deposits, and Aburied is the burial
area. A 5 m constant was used in agreement with the thickness measured on the field of the
exposed phreatomagmatic units. In the volume calculations a high resolution Light Detection and
Ranging (LiDAR) DSM was used. The volcanic unit boundaries were mapped out on the field, and
later verified on the derivative products of the LiDAR DSM, such as hillshade and slope angle maps.
The elevation points along the margin of each volcanic unit were extracted to use these points in
modelling of the contact zone between volcanic deposits and pre-eruptive country rocks. Using
these elevation points, this contact zone was approximated by a Triangulated Irregular Network
(TIN) model. The cone height was defined as absolute height between the LiDAR DSM and the
modelled base around each cone. The cone and crater diameter values obtained from the field were
verified as the average from the major and minor axis of the best-fit ellipse. The slope angles were
calculated for the cones from the LiDAR DSM by an unweighted, linear filter [e.g. PREWITT filter;
(Prewitt, 1970)] (Fig. 8A). Finally, bulk eruptive volumes were calculated as the space enclosed
between the LiDAR DSM and an interpreted volcanic unit distribution based on the field work as
shown in Fig. 8B; then bulk volumes were corrected to Dense Rock Equivalent (DRE) values (Table
A2).
Table A1. Estimated percentages used for DRE volume corrections in the Al-Du’aythah cones.
Volcanic unit
Lava flow
Massive
scoriaceous
deposits
Stratified,
country-rich
deposits
Country-rock
content
(%)
0
First step
Inter-particle
void space
(%)
5
Volcanic
content
(%)
95
Second step
Intra-particle
DRE juvenile
void space
content
(%)
(%)
10
90
0
50
50
50
50
70
10
20
5
95
Table A2. Morphometry parameters and calculated volumes for the four cones of the Al-Du’aythah cones.
Shape descriptor
Cone height
Major
Diameter
Minor
crater
Mean
Major
Diameter
Minor
cone
Mean
Mean
Slope
Median
Mode
Amassive deposits
Alava flow
Area
Astratified deposits
Aburied
ATOTAL
Vmassive deposits
Vlava low
Bulk
Vstratified deposits
volume
Vstratified deposits corrected
VTOTAL
Vmassive deposits
Vlava flow
DRE
volume
Vstratified deposits corrected
VTOTAL
Unit
m
m
m
m
m
m
m
degree
degree
degree
10-3 km2
10-3 km2
10-3 km2
10-3 km2
10-3 km2
10-6 km3
10-6 km3
10-6 km3
10-6 km3
10-6 km3
10-6 km3
10-6 km3
10-6 km3
10-6 km3
Cone 1
39
43
33
38
215
147
181
28
29
31
21
0
0
0
21
300
0
0
0
300
75
0
0
75
Cone 2
35
96
65
81
261
177
219
24
26
29
24
0
15
24
39
200
0
35
121
356
50
0
30
80
Cone 3
36
100
98
99
204
155
179
24
23
35
36
5
11
36
52
374
12
17
182
585
94
10
38
141
Cone 4
26
107
43
75
171
161
166
19
19
19
24
20
9
24
53
244
40
18
121
423
61
35
26
122
References
Kereszturi G, Németh K, Cronin S J, Agustín-Flores J, Smith I E & Lindsay J (2013) A model for
calculating eruptive volumes for monogenetic volcanoes - Implication for the
Quaternary Auckland Volcanic Field, New Zealand. J Volcanol Geotherm Res 266:16-33
Prewitt, J M (1970) Object enhancement and extraction. Picture processing and
Psychopictorics, 10, 15-19.