 |
 |
|
|
|
Tectonic refers to
rock-deforming processes and resulting structures that occur over
large sections of the
lithosphere.
|
The tectonic plates
are the large, thin, relatively rigid plates that move relative to
one another on the outer surface of the Earth.
|
Teleseismic is
pertaining to earthquakes at distances greater than 1,000 km from
the measurement site.
|
Tensional
stress is the stress that tends to pull something apart.
It is the stress component perpendicular to a given
surface, such as a fault plane, that results from forces
applied perpendicular to the surface or from remote forces
transmitted through the surrounding rock.
(Image courtesy of Michael Kimberly,
North Carolina State Univ.)
|
Fault
A fault is a fracture
along which the blocks of
crust on either side have moved relative to one another
parallel to the fracture.
Dip-slip
Dip-slip faults
are inclined fractures where the blocks have mostly shifted
vertically. If the rock mass above an inclined fault moves down,
the fault is termed normal, whereas if the rock above the
fault moves up, the fault is termed reverse. A thrust
fault is a reverse fault with a dip of 45° or less. Oblique-slip
faults have significant components of different slip styles.
|
The time history is
the sequence of values of any time-varying quantity (such as a
ground motion measurement) measured at a set of fixed times. Also
termed time series.
|
A transform fault is
a special variety of strike-slip fault that accommodates relative
horizontal slip between other
tectonic elements, such as oceanic crustal plates. Often
extend from
oceanic ridges.
(From "This Dynamic Earth: The Story of Plate
Tectonics", U.S. Geological Survey.)
|
A traveltime curve is
a graph of arrival times, commonly
P or
S waves, recorded at different points as a function of
distance from the seismic
source. Seismic velocities within the earth can be computed
from the slopes of the resulting curves.
(Frank Wattenberg, Department of Mathematics,
Montana State University)
|
A tsunami is a sea
wave of local or distant origin that results from large-scale
seafloor displacements associated with large earthquakes, major
submarine slides, or exploding volcanic islands.
|
Tsunamigenic is
referring to those earthquakes, commonly along major
subduction-zone plate boundaries such as those bordering the
Pacific Ocean, that can generate tsunamis.
(Image from Western Region Coastal and Marine
Geology, U.S. Geological Survey)
|
The tsunami
magnitude, or Mt, is a number used to compare sizes of tsunamis
generated by different earthquakes and calculated from the
logarithm of the maximum amplitude of the tsunami wave measured by
a tide gauge distant from the tsunami source.
|
|
 |
|
