Abstract The Indian Ocean earthquake of 26 December 2004 led to significant
ground deformation in... more Abstract The Indian Ocean earthquake of 26 December 2004 led to significant ground deformation in the Andaman and Nicobar region, accounting for !800 km of the rupture. Part of this article deals with coseismic changes along these islands, observable from coastal morphology, biological indicators, and Global Positioning System (GPS) data. Our studies indicate that the islands south of 10" N latitude coseismically subsided by 1–1.5 m, both on their eastern and western margins, whereas those to the north showed a mixed response. The western margin of the Middle Andaman emerged by #1 m, and the eastern margin submerged by the same amount. In the North Andaman, both western and eastern margins emerged by #1 m. We also assess the pattern of long-term deformation (uplift/subsidence) and attempt to reconstruct earthquake/tsunami history, with the available data. Geological evidence for past submergence includes dead mangrove vegetation dating to 740 ! 100 yr B.P., near Port Blair and peat layers at 2–4 m and 10–15 m depths observed in core samples from nearby locations. Preliminary paleoseismological/tsunami evidence from the Andaman and Nicobar region and from the east coast of India, suggest at least one predecessor for the 2004 earthquake 900–1000 years ago. The history of earthquakes, although incomplete at this stage, seems to imply that the 2004-type earthquakes are infrequent and follow variable intervals.
Changes beneath a volcano can be observed through position changes in a GPS network, but distingu... more Changes beneath a volcano can be observed through position changes in a GPS network, but distinguishing the source of site motion is not always straightforward. The records of continuous GPS sites provide a favorable data set for tracking magma migration. Dense ...
In 2005 a repeat GPS campaign was conducted at 12 sites on Mt.Veniaminof Volcano and the surround... more In 2005 a repeat GPS campaign was conducted at 12 sites on Mt.Veniaminof Volcano and the surrounding region. A previous survey in 2002 provided initial locations for the sites. The deformation that occurred in the three years between the two surveys consist of ∼24 cm of ...
During the past 5-10 Ma, the Yakutat terrane has been colliding with and subducting beneath the A... more During the past 5-10 Ma, the Yakutat terrane has been colliding with and subducting beneath the Alaskan part of the North American Plate. Modeling of GPS data and analysis of deep-crustal structure bolster a hypothesized connection between the terrane collision and seismogenesis. GPS data collected near Prince William Sound indicate that forearc subsidence following the 1964 Great Alaska Earthquake (Mw=9.2)
Abstract The Indian Ocean earthquake of 26 December 2004 led to significant
ground deformation in... more Abstract The Indian Ocean earthquake of 26 December 2004 led to significant ground deformation in the Andaman and Nicobar region, accounting for !800 km of the rupture. Part of this article deals with coseismic changes along these islands, observable from coastal morphology, biological indicators, and Global Positioning System (GPS) data. Our studies indicate that the islands south of 10" N latitude coseismically subsided by 1–1.5 m, both on their eastern and western margins, whereas those to the north showed a mixed response. The western margin of the Middle Andaman emerged by #1 m, and the eastern margin submerged by the same amount. In the North Andaman, both western and eastern margins emerged by #1 m. We also assess the pattern of long-term deformation (uplift/subsidence) and attempt to reconstruct earthquake/tsunami history, with the available data. Geological evidence for past submergence includes dead mangrove vegetation dating to 740 ! 100 yr B.P., near Port Blair and peat layers at 2–4 m and 10–15 m depths observed in core samples from nearby locations. Preliminary paleoseismological/tsunami evidence from the Andaman and Nicobar region and from the east coast of India, suggest at least one predecessor for the 2004 earthquake 900–1000 years ago. The history of earthquakes, although incomplete at this stage, seems to imply that the 2004-type earthquakes are infrequent and follow variable intervals.
Changes beneath a volcano can be observed through position changes in a GPS network, but distingu... more Changes beneath a volcano can be observed through position changes in a GPS network, but distinguishing the source of site motion is not always straightforward. The records of continuous GPS sites provide a favorable data set for tracking magma migration. Dense ...
In 2005 a repeat GPS campaign was conducted at 12 sites on Mt.Veniaminof Volcano and the surround... more In 2005 a repeat GPS campaign was conducted at 12 sites on Mt.Veniaminof Volcano and the surrounding region. A previous survey in 2002 provided initial locations for the sites. The deformation that occurred in the three years between the two surveys consist of ∼24 cm of ...
During the past 5-10 Ma, the Yakutat terrane has been colliding with and subducting beneath the A... more During the past 5-10 Ma, the Yakutat terrane has been colliding with and subducting beneath the Alaskan part of the North American Plate. Modeling of GPS data and analysis of deep-crustal structure bolster a hypothesized connection between the terrane collision and seismogenesis. GPS data collected near Prince William Sound indicate that forearc subsidence following the 1964 Great Alaska Earthquake (Mw=9.2)
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ground deformation in the Andaman and Nicobar region, accounting for !800 km
of the rupture. Part of this article deals with coseismic changes along these islands,
observable from coastal morphology, biological indicators, and Global Positioning
System (GPS) data. Our studies indicate that the islands south of 10" N latitude
coseismically subsided by 1–1.5 m, both on their eastern and western margins,
whereas those to the north showed a mixed response. The western margin of the
Middle Andaman emerged by #1 m, and the eastern margin submerged by the same
amount. In the North Andaman, both western and eastern margins emerged by #1 m.
We also assess the pattern of long-term deformation (uplift/subsidence) and attempt
to reconstruct earthquake/tsunami history, with the available data. Geological evidence
for past submergence includes dead mangrove vegetation dating to 740 !
100 yr B.P., near Port Blair and peat layers at 2–4 m and 10–15 m depths observed
in core samples from nearby locations. Preliminary paleoseismological/tsunami evidence
from the Andaman and Nicobar region and from the east coast of India, suggest
at least one predecessor for the 2004 earthquake 900–1000 years ago. The history of
earthquakes, although incomplete at this stage, seems to imply that the 2004-type
earthquakes are infrequent and follow variable intervals.
ground deformation in the Andaman and Nicobar region, accounting for !800 km
of the rupture. Part of this article deals with coseismic changes along these islands,
observable from coastal morphology, biological indicators, and Global Positioning
System (GPS) data. Our studies indicate that the islands south of 10" N latitude
coseismically subsided by 1–1.5 m, both on their eastern and western margins,
whereas those to the north showed a mixed response. The western margin of the
Middle Andaman emerged by #1 m, and the eastern margin submerged by the same
amount. In the North Andaman, both western and eastern margins emerged by #1 m.
We also assess the pattern of long-term deformation (uplift/subsidence) and attempt
to reconstruct earthquake/tsunami history, with the available data. Geological evidence
for past submergence includes dead mangrove vegetation dating to 740 !
100 yr B.P., near Port Blair and peat layers at 2–4 m and 10–15 m depths observed
in core samples from nearby locations. Preliminary paleoseismological/tsunami evidence
from the Andaman and Nicobar region and from the east coast of India, suggest
at least one predecessor for the 2004 earthquake 900–1000 years ago. The history of
earthquakes, although incomplete at this stage, seems to imply that the 2004-type
earthquakes are infrequent and follow variable intervals.