Glossary - The Solid Earth - page 662

potential energy energy a body has by virtue of its position.
polarization of shear waves vertically polarized S-waves, termed SV, have their particle
motion in the plane containing the source, the receiver and the centre of the Earth.
Horizontally polarized S-waves, termed SH, have their particle motion orthogonal to this
plane.
primary waves see body waves.
P-waves see body waves.
quartz crystals of silicon dioxide, SiO 2 .
radioactive decay spontaneous decay of nucleus of an atom.
range horizontal distance between a shot point and receiver.
Rayleigh wave surface wave for which the particle motion is in the vertical plane that
includes the direction of propagation of the wave.
REE rare-earth element; the fifteen metallic elements with atomic numbers 57-71: La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.
refraction bending of rays (light or sound) when they pass from one medium to another.
refractory mineral or element that remains solid during partial melting.
rift region where the crust has split apart, usually marked by a rift valley (e.g., East African
Rift, Rhine graben).
right-lateral fault, dextral fault fault on which the displacement is such that, to an observer
on the ground, the opposite side is displaced to the right.
scalar quantity that has a magnitude but not a direction.
secondary waves another name for S-waves. See body waves.
sedimentary rocks rock made up of fragments of other rocks, usually resulting from the
action of wind, water or ice.
seismic discontinuity surface within the Earth at which the seismic P- and/or S-wave
velocities change.
seismicity distribution of earthquakes in space and time.
seismograph, seismometer instrument that measures motion of the ground.
seismology study of earthquakes and the passage of seismic waves through the Earth.
serpentine group of minerals in the family (Mg,Fe) 3 Si 2 O 5 (OH) 4 , formed by the hydration of
ferromagnesium-rich silicates (e.g., olivine and pyroxene).
serpentinization alteration of olivine to serpentine by hydration.
shale fine-grained sedimentary rock.
silicate large class of minerals containing silicon and oxygen as SiO 4 ; they make up most of
the Earth's crust.