the site several years after the event. Later, Taylor et al.
(1980, 1987) mapped the uplift with hundreds of systematic measurements of emerged corals and used the data
to analyze seismic slip. Maximum uplift for the 1965
event as measured in 1976 was $1.2 m. Additional
coseismic uplift of Northern Malakula reefs occurred in
association with a July 1994 earthquake south of Malakula
Island (Calmant et al., 1999). Also, Pelletier et al. (2000)
measured uplift of Ambrym Island, Vanuatu, near
a back-arc reverse-fault earthquake in 1999.
In some cases, maximum coseismic reef uplift or subsidence may be only a few centimeters or less, as discovered
by Pandolfi et al. (1994) following a May 1992 M $7.2
earthquake along the northeast coast of Papua New Guinea.
Other scientific reports of coseismic reef uplift include the
Caribbean coast of Costa Rica (Plafker and Ward, 1992)
and the Solomon Islands (Taylor et al., 2008). However,
the most spectacular reports of coseismic reef uplift are for
the great M w $9.1 26 December 2004 Sumatra-Andaman
earthquake that ruptured from northern Sumatra northward
past the Andaman and Nicobar Islands producing uplift up
to 1.5 m on some islands (Bilham et al., 2005; Meltzner
et al., 2006; Rajendran et al., 2007). Subsequently on 28
March 2005, an adjacent area of the forearc ruptured
beneath Nias Island causing uplift as great as 3 m, but over
a smaller area (Briggs et al., 2006).
Informed by the historical reports of volcanogenic
coseismic uplifts near Yasur Volcano (Lawrie, 1898;
Mawson, 1905) on Tanna Island, Vanuatu, Chen et al.
(1995) measured a combined uplift of $20 m based on
well-preserved branching corals and heads on the forest
floor. Uranium-series and radiocarbon dating confirmed that
the corals died $1878 A.D. and documented several previous uplifts that sum to $160 m cumulatively over the past
$1,100 years, possibly related to magma chamber inflation.
Most if not all of this uplift was confined to the Yenkahe
horst area and is not detectable elsewhere on Tanna Island.
Earthquakes may have accompanied uplift of coastal
volcanic Mount Suribachi on Iwo Jima (Newhall et al.,
1998) and $6 m of 1954 uplift of Urvina Bay, on the volcanic Isabela Island, Galapagos (Couffer, 1956; Colgan and
Malmquist, 1987) may have been accompanied by earthquakes. A M $6.5 earthquake occurred on 4 June 1954 near
Urvina Bay (Geist et al., 1994). Even apparently aseismic
uplift of volcanic islands is often accompanied by at least
small earthquakes as at Iwo Jima (Ukawa et al., 1998).
Scientific significance of coseismically emerged
coral reefs
Measurements of the amount and geography of coastal
uplift and subsidence associated with the great 1960 Chile
and 1964 Alaska earthquakes (e.g., Plafker, 1965; Plafker
and Savage, 1970) demonstrated that vertical displacement could provide critical information about subduction
processes at convergent plate boundaries. Subsequently,
several coseismic reef uplifts have been used to investigate the physical parameters of earthquake faulting.
The amounts and timing of recent and ancient coral reef
emergence or submergence events in both volcanic settings and near potentially active faults provides a basis
for forecasting the probability of future events (e.g., Sieh
et al., 2008). Volcanically related coseismic uplifts may
serve as a measure of subsurface volcanic activity such
as magma chamber inflation and help scientists to understand the deformation processes affecting volcanic edifices (e.g, Geist et al., 1994; Amelung et al., 2000).
Most reported coseismic vertical reef displacements
have occurred in association with thrust-type earthquakes
in subduction zones, usually on the main interplate
megathrust or decollement. However, the 1992 coseismic
uplift of part of the Huon Peninsula reef occurred where
the Australian continent has collided with an island arc
and probably occurred on a fault developed to accommodate collision deformation rather than being on the
interplate megathrust. The 1999 coseismic uplift of the
eastern part of Ambrym Island in Vanuatu was related to
a M w 7.5 event on a steeply dipping backthrust reverse
fault accommodating eastward displacement of several
segments of the central Vanuatu arc system (Pelletier
et al., 2000; Regnier et al., 2003).
Crustal displacement associated with seismic fault rupture represents the release of elastic energy stored in the
lithosphere that accumulated during the interseismic
period preceding the earthquake. Rupture of most convergent margin faults typically involves both horizontal and
vertical coseismic displacements that are greatest overlying and adjacent to the fault, but also extending many tens
of kilometers beyond the rupture zone. The amount and
geographic distribution of vertical displacement may
enable mapping of the rupture zone geometry and an
assessment of the nature of interplate slip along the
megathrust (e.g., Plafker and Savage, 1970; Taylor et al.,
1987; Sieh et al., 1999; Briggs et al., 2006; Chlieh et al.,
2007; Sieh et al., 2008). Scientists used corals and shorelines to document the geographic pattern of subsidence
and uplift as great as 1.5–2 m following the great M w
$9.1 26 December 2004 Aceh earthquake (Bilham et al.,
2005; Meltzner et al., 2006; Subarya et al., 2006;
Rajendran et al., 2007). The measurements of uplift and
subsidence constrained the temporal and spatial extent of
the earthquake rupture geometry and processes (Subarya
et al., 2006).
Where elastic strain release on a thrust fault or
megathrust culminates in coseismic uplift and subsidence
of the forearc, one can assume that the event represents
only one stage in the greater long-term earthquake cycle
of repeated elastic strain accumulation and coseismic
release (e.g., Plafker and Savage, 1970; Savage, 1983;
Sieh et al., 2008). Elastic strain typically accumulates for
tens or even thousands of years prior to coseismic rupture;
while strain accumulates there is slow subsidence over the
locked part of a thrust fault zone, opposite to the direction
of coseismic uplift (e.g., Savage, 1983). Thus, an area of
coseismic coral reef uplift is likely to become an area of
interseismic coral reef subsidence. If the system was
EARTHQUAKES AND EMERGENCE OR SUBMERGENCE OF CORAL REEFS
329
(1980, 1987) mapped the uplift with hundreds of systematic measurements of emerged corals and used the data
to analyze seismic slip. Maximum uplift for the 1965
event as measured in 1976 was $1.2 m. Additional
coseismic uplift of Northern Malakula reefs occurred in
association with a July 1994 earthquake south of Malakula
Island (Calmant et al., 1999). Also, Pelletier et al. (2000)
measured uplift of Ambrym Island, Vanuatu, near
a back-arc reverse-fault earthquake in 1999.
In some cases, maximum coseismic reef uplift or subsidence may be only a few centimeters or less, as discovered
by Pandolfi et al. (1994) following a May 1992 M $7.2
earthquake along the northeast coast of Papua New Guinea.
Other scientific reports of coseismic reef uplift include the
Caribbean coast of Costa Rica (Plafker and Ward, 1992)
and the Solomon Islands (Taylor et al., 2008). However,
the most spectacular reports of coseismic reef uplift are for
the great M w $9.1 26 December 2004 Sumatra-Andaman
earthquake that ruptured from northern Sumatra northward
past the Andaman and Nicobar Islands producing uplift up
to 1.5 m on some islands (Bilham et al., 2005; Meltzner
et al., 2006; Rajendran et al., 2007). Subsequently on 28
March 2005, an adjacent area of the forearc ruptured
beneath Nias Island causing uplift as great as 3 m, but over
a smaller area (Briggs et al., 2006).
Informed by the historical reports of volcanogenic
coseismic uplifts near Yasur Volcano (Lawrie, 1898;
Mawson, 1905) on Tanna Island, Vanuatu, Chen et al.
(1995) measured a combined uplift of $20 m based on
well-preserved branching corals and heads on the forest
floor. Uranium-series and radiocarbon dating confirmed that
the corals died $1878 A.D. and documented several previous uplifts that sum to $160 m cumulatively over the past
$1,100 years, possibly related to magma chamber inflation.
Most if not all of this uplift was confined to the Yenkahe
horst area and is not detectable elsewhere on Tanna Island.
Earthquakes may have accompanied uplift of coastal
volcanic Mount Suribachi on Iwo Jima (Newhall et al.,
1998) and $6 m of 1954 uplift of Urvina Bay, on the volcanic Isabela Island, Galapagos (Couffer, 1956; Colgan and
Malmquist, 1987) may have been accompanied by earthquakes. A M $6.5 earthquake occurred on 4 June 1954 near
Urvina Bay (Geist et al., 1994). Even apparently aseismic
uplift of volcanic islands is often accompanied by at least
small earthquakes as at Iwo Jima (Ukawa et al., 1998).
Scientific significance of coseismically emerged
coral reefs
Measurements of the amount and geography of coastal
uplift and subsidence associated with the great 1960 Chile
and 1964 Alaska earthquakes (e.g., Plafker, 1965; Plafker
and Savage, 1970) demonstrated that vertical displacement could provide critical information about subduction
processes at convergent plate boundaries. Subsequently,
several coseismic reef uplifts have been used to investigate the physical parameters of earthquake faulting.
The amounts and timing of recent and ancient coral reef
emergence or submergence events in both volcanic settings and near potentially active faults provides a basis
for forecasting the probability of future events (e.g., Sieh
et al., 2008). Volcanically related coseismic uplifts may
serve as a measure of subsurface volcanic activity such
as magma chamber inflation and help scientists to understand the deformation processes affecting volcanic edifices (e.g, Geist et al., 1994; Amelung et al., 2000).
Most reported coseismic vertical reef displacements
have occurred in association with thrust-type earthquakes
in subduction zones, usually on the main interplate
megathrust or decollement. However, the 1992 coseismic
uplift of part of the Huon Peninsula reef occurred where
the Australian continent has collided with an island arc
and probably occurred on a fault developed to accommodate collision deformation rather than being on the
interplate megathrust. The 1999 coseismic uplift of the
eastern part of Ambrym Island in Vanuatu was related to
a M w 7.5 event on a steeply dipping backthrust reverse
fault accommodating eastward displacement of several
segments of the central Vanuatu arc system (Pelletier
et al., 2000; Regnier et al., 2003).
Crustal displacement associated with seismic fault rupture represents the release of elastic energy stored in the
lithosphere that accumulated during the interseismic
period preceding the earthquake. Rupture of most convergent margin faults typically involves both horizontal and
vertical coseismic displacements that are greatest overlying and adjacent to the fault, but also extending many tens
of kilometers beyond the rupture zone. The amount and
geographic distribution of vertical displacement may
enable mapping of the rupture zone geometry and an
assessment of the nature of interplate slip along the
megathrust (e.g., Plafker and Savage, 1970; Taylor et al.,
1987; Sieh et al., 1999; Briggs et al., 2006; Chlieh et al.,
2007; Sieh et al., 2008). Scientists used corals and shorelines to document the geographic pattern of subsidence
and uplift as great as 1.5–2 m following the great M w
$9.1 26 December 2004 Aceh earthquake (Bilham et al.,
2005; Meltzner et al., 2006; Subarya et al., 2006;
Rajendran et al., 2007). The measurements of uplift and
subsidence constrained the temporal and spatial extent of
the earthquake rupture geometry and processes (Subarya
et al., 2006).
Where elastic strain release on a thrust fault or
megathrust culminates in coseismic uplift and subsidence
of the forearc, one can assume that the event represents
only one stage in the greater long-term earthquake cycle
of repeated elastic strain accumulation and coseismic
release (e.g., Plafker and Savage, 1970; Savage, 1983;
Sieh et al., 2008). Elastic strain typically accumulates for
tens or even thousands of years prior to coseismic rupture;
while strain accumulates there is slow subsidence over the
locked part of a thrust fault zone, opposite to the direction
of coseismic uplift (e.g., Savage, 1983). Thus, an area of
coseismic coral reef uplift is likely to become an area of
interseismic coral reef subsidence. If the system was
EARTHQUAKES AND EMERGENCE OR SUBMERGENCE OF CORAL REEFS
329