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Legend to Fault Names
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EPGFZ:
Enriquillo-Plantain Garden fault zone
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SFZ:
Septentrional fault zone
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H-BCZ:
Hispaniola-Bahamas collision zone
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NPRSFZ:
North Puerto Rico Slope fault zone
Caribbean Plate Characteristics
The Caribbean plate is a rigid
lithospheric, oceanic plate that behaves like a continental plate,
probably due to its unusually thick oceanic crust (Burke et al., 1984.
It has several features of active deformation, uncommon to oceanic plates.
These include numerous intraplate earthquakes, intraplate faulting
affecting young sediments, and strike-slip mechanisms for intraplate
earthquakes and intraplate volcanism (Burke et al., 1984).
Hispaniola and Jamaica
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Faults
striking north of west are
linked with thrusting and folding, while faults striking south of west
are a result of extension with pull-apart segments (Burke et al, 1984).
This provides evidence that the motion of North America with respect to the Caribbean is
E-W (Burke et al, 1984).
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Shallow, moderate, intraplate earthquakes,
near Jamaica and the
Virgin Islands, are
caused by internal deformation of the North American plate.
Concentrations of these earthquakes take place at depths up to 200 km.
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North Hispaniola fault
movement offshore of north Hispaniola
is estimated to be 4±3 mm/yr (Dixon, et al, 1998).
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Septentrional fault movement in northern Dominican Republic is at a
rate of 8±3 mm/yr (Dixon et al, 1998).
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Enriquillo fault movement in southern Dominican Republic and Haiti is 8±4 mm/yr (Dixon et al, 1998).
Puerto Rico
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Puerto Rico lies inside a transition
zone between subduction to the east and a transform zone to
the west (Prentice et al, 1997).
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North Puerto Rico Slope
fault zone (50-100 km off the
coast of northern Puerto Rico) is the major structure associated with
this transform boundary (Prentice et al, 1997). This boundary
travels west of Puerto Rico and is exposed on Hispaniola island as the
Septentrional fault zone (Prentice et al, 1997). West of
Hispaniola, it continues as a complex system of submarine left-lateral
faults that extends across the Caribbean Sea to Central America
(Prentice et al, 1997).
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Most of the earthquakes in
the north-central Caribbean occur south of the Puerto Rico trench
with virtually no seismicity beneath the southern Bahamas (except
beneath the western edge of the Silver Bank collision zone) (Dolan et
al., 1998).
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Shallow- to deep-focus
earthquakes occur beneath eastern Hispaniola and Puerto Rico, but only
shallow-focus quakes occur west of 71°W (Dolan et al., 1998). This
change coincides with the leading, western edge of the Silver-Navidad
bank collision zone.
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