Environmental Engineering Reference
In-Depth Information
Table 14.1 Estimates of global, time-averaged
fluxes of magma in different tectonic
settings.
(a) Estimates of global time-averaged magmatic
fluxes (from Crisp, 1984 )
km 3 /yr,
intruded
km 3 /yr,
extruded
Tg/yr magma erupted
subaerially a
Setting
Arc magmatism
2.5
-
8
0.4
-
0.6
1,000
-
1,500
Continental intraplate
magmatism
0.1
-
1.5
0.03
-
0.1
75
-
250
Oceanic intraplate
magmatism
1.5
-
2
0.3
-
0.4
750
-
1,000
Ocean ridge magmatism
(submarine)
18
3
0
Total
22
-
30
3.7
-
4.1
1,800
-
2,800
(b) Global magmatic
fluxes in volcanic arcs
km 3 /yr
Tg/yr a
Method
0.4 b
Erupted tephra
ux
1000
1.7 c
Flux based on arc length and productivity
0.3
-
750
-
4300
3.4 d
Flux based on volcano productivity
1.7
-
4,300
-
8,500
(c) Time-averaged volcanic output rates, by
field or volcano (from White et al ., 2006 )
km 3 /yr
Tg/yr a
10 - 1
Flood basalts (during eruptive periods)
9 (
￿
2)
￿
2,200
￿
500
10 - 2
Oceanic volcanoes, other than
flood basalts
2.8 (
￿
0.4)
￿
70
￿
10
10 - 3
Continental volcanoes, other than
flood basalts
4.4 (
￿
0.8)
￿
11
￿
2
a Assuming magma density of 2,500 kg/m 3 .
b Based on explosive eruption rates over past 2,000 years (Pyle, 1995 ).
c For a global arc length of 33,000 km and a time-averaged magmatic
50) km 3
per Myr per km of arc, based on compilations of volcano size (southern volcanic zone,
Chile, past 500 kyr; Völker et al ., 2011 ; Central America, past 600 kyr; Carr et al ., 2007 ;
accounting for cumulate masses and tephra, Kutterolf et al ., 2008 ), and studies of
emplacement rates in the Sierra Nevada Batholith (Paterson et al ., 2011 ).
d Assuming 839 active arc volcanoes, and a magmatic
flux of (10
-
flux per volcano of
3km 3 per yr (Syracuse and Abers, 2006 ; White et al ., 2006 ).
(2
-
4)
￿
10
-
Here we focus on emissions direct to the atmosphere rather than those from
submarine activity. Table 14.2 summarises some of the characteristics of how
different subaerial types of volcanism inject gas into the atmosphere. While the
final environmental impacts of volcanic activity depend on many factors, here we
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