Physical parameters (5): Geometry of magma
reservoirs
Controversy between petrologists and seismologists
Old magma chamber exists:
Petrological observations:
Skaergaard (Greenland), Stillwater
(US),
Bushweld (South Africa)
Horizontal extent: 10 to 100 km
Vertical extent: few km to 10 km
Aseismic zones mark zones rich
in liquid but no
large reservoir
is seismically observed
A plexus of dikes ?
+ existence of
potential levels for « horizontal » magma
accumulation, with a shallow
reservoir and deep ones