E
EARTHQUAKES AND EMERGENCE OR
SUBMERGENCE OF CORAL REEFS
Frederick W. Taylor
John A. and Katherine G. Jackson School of Geosciences,
University of Texas at Austin, Austin, TX, USA
Synonyms
Coseismic displacement of coral reefs; Coseismic emergence or submergence of coral reefs
Definition
Earthquakes and emergence or submergence of coral
reefs: refers to vertical tectonic displacement of coral reefs
associated with an earthquake. Coseismic vertical motion
may cause submergence or raise the shallow part of reefs
to levels relative to sea level above where they can live.
The amount of vertical motion may be barely detectable
or can exceed 10 m. Subsidence is less obvious than uplift,
but both provide significant information regarding earthquakes and tectonic processes.
Introduction
Early geologists realized that crustal uplift and subsidence
as well as sea-level changes helped to create atolls and barrier reefs and emplace fossil coral reefs at elevations from
slightly above to hundreds of meters above sea level (e.g.,
Darwin, 1842; Guppy, 1887; Dana, 1890). However, the
relationship to earthquakes, and the causes, frequency,
rates, and amounts of vertical movement for each event
were matters of conjecture until examples of coseismic
reef uplift were described in scientific reports (e.g.,
Figure 1; Taylor et al., 2008). Today, we know that both
coseismic and aseismic mechanisms cause vertical
displacement, but coseismic movement is nearly
instantaneous and much more dramatic. In extreme cases,
uplift may be as great as $20 m. Coseismic uplift is generally easier to recognize and document than subsidence
because it causes emergence and mortality of coral and
other organisms raised higher than their highest level of
survival (HLS) (Taylor et al., 1987).
Coseismic reef uplift and subsidence have been
documented in two geologic settings: (1) Near volcanoes
along plate boundaries or intraplate hot spots where processes such as magma chamber inflation induce motion on
faults, earthquakes, and vertical motion (e.g., Newhall and
Dzurizin, 1988; Kaizuka, 1992; Geist et al., 1994; Amelung
et al., 2000) and (2) compressional tectonic settings along
plate boundaries where vertical surface displacement commonly accompanies fault rupture. Emerged coral reefs also
occur on restraining bends along the trace of strike-slip plate
boundaries as along the North American-Caribbean plate
boundary zone in Haiti (e.g., Dodge et al., 1983; Mann
et al., 1995). Just before final submission of this manuscript
significant reef uplift associated with a January 2010 earthquake along a strike-slip fault in southern Haiti has been
reported (personal communication, Roger Bilham). This
may be the first documented case of coseismic reef uplift
along a strike-slip fault system.
Today, coral reef emergence and submergence often are
measured and used to investigate aspects of the subduction process. The vertical displacements of coral reefs
record the amounts and distribution of elastic strain accumulation and its release as coseismic and aseismic slip.
Measurements of vertical motions provide direct information about the mechanical processes accompanying volcanism and fault slip.
Mysterious origin of emerged and submerged
coral reefs
Geologists have long been intrigued by the mysterious origins of atolls and emerged coral reefs and debated the
David Hopley (ed.), Encyclopedia of Modern Coral Reefs, DOI 10.1007/978-90-481-2639-2,
# Springer Science+Business Media B.V. 2011
EARTHQUAKES AND EMERGENCE OR
SUBMERGENCE OF CORAL REEFS
Frederick W. Taylor
John A. and Katherine G. Jackson School of Geosciences,
University of Texas at Austin, Austin, TX, USA
Synonyms
Coseismic displacement of coral reefs; Coseismic emergence or submergence of coral reefs
Definition
Earthquakes and emergence or submergence of coral
reefs: refers to vertical tectonic displacement of coral reefs
associated with an earthquake. Coseismic vertical motion
may cause submergence or raise the shallow part of reefs
to levels relative to sea level above where they can live.
The amount of vertical motion may be barely detectable
or can exceed 10 m. Subsidence is less obvious than uplift,
but both provide significant information regarding earthquakes and tectonic processes.
Introduction
Early geologists realized that crustal uplift and subsidence
as well as sea-level changes helped to create atolls and barrier reefs and emplace fossil coral reefs at elevations from
slightly above to hundreds of meters above sea level (e.g.,
Darwin, 1842; Guppy, 1887; Dana, 1890). However, the
relationship to earthquakes, and the causes, frequency,
rates, and amounts of vertical movement for each event
were matters of conjecture until examples of coseismic
reef uplift were described in scientific reports (e.g.,
Figure 1; Taylor et al., 2008). Today, we know that both
coseismic and aseismic mechanisms cause vertical
displacement, but coseismic movement is nearly
instantaneous and much more dramatic. In extreme cases,
uplift may be as great as $20 m. Coseismic uplift is generally easier to recognize and document than subsidence
because it causes emergence and mortality of coral and
other organisms raised higher than their highest level of
survival (HLS) (Taylor et al., 1987).
Coseismic reef uplift and subsidence have been
documented in two geologic settings: (1) Near volcanoes
along plate boundaries or intraplate hot spots where processes such as magma chamber inflation induce motion on
faults, earthquakes, and vertical motion (e.g., Newhall and
Dzurizin, 1988; Kaizuka, 1992; Geist et al., 1994; Amelung
et al., 2000) and (2) compressional tectonic settings along
plate boundaries where vertical surface displacement commonly accompanies fault rupture. Emerged coral reefs also
occur on restraining bends along the trace of strike-slip plate
boundaries as along the North American-Caribbean plate
boundary zone in Haiti (e.g., Dodge et al., 1983; Mann
et al., 1995). Just before final submission of this manuscript
significant reef uplift associated with a January 2010 earthquake along a strike-slip fault in southern Haiti has been
reported (personal communication, Roger Bilham). This
may be the first documented case of coseismic reef uplift
along a strike-slip fault system.
Today, coral reef emergence and submergence often are
measured and used to investigate aspects of the subduction process. The vertical displacements of coral reefs
record the amounts and distribution of elastic strain accumulation and its release as coseismic and aseismic slip.
Measurements of vertical motions provide direct information about the mechanical processes accompanying volcanism and fault slip.
Mysterious origin of emerged and submerged
coral reefs
Geologists have long been intrigued by the mysterious origins of atolls and emerged coral reefs and debated the
David Hopley (ed.), Encyclopedia of Modern Coral Reefs, DOI 10.1007/978-90-481-2639-2,
# Springer Science+Business Media B.V. 2011