New GPS constraints on the motion of the Yakutat Block

Fletcher, Hilary J.; Freymueller, J. T.

doi:10.1029/1999gl005346

Cited by 71 publications

(76 citation statements)

References 18 publications

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“…The E edge of yak with NA is marked by the Fairweather transform fault. Relative to NA, yak is moving 50.3 ± 0.8 mm/yr at an azimuth of N 22.9 ± 0.6° W, which was measured at the community of Yakutat, Alaska [5,32,33]. PAC is theoretically predicted to be moving 50.9 mm/yr at an azimuth of N14.6°W at this same location relative to NA.…”

Section: The "Yak" Part Of the Yakutat Platementioning

confidence: 76%

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The Active Yakutat (Kula?) Plate and Its Southcentral Alaska Megathrust and Intraplate Earthquakes

Reeder¹

2016

JEASE

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Alaska geology and plate tectonics have not been well understood due to an active Yakutat plate, believed to be part of the remains of an ancient Kula plate, not being acknowledged to exist in Alaska. It is positioned throughout most of southcentral Alaska beneath the North American plate and above the NNW subducting Pacific plate. The Kula? plate and its eastern spreading ridge were partially "captured" by the North American plate in the Paleocene. Between 63 Ma and 32 Ma, large volumes of volcanics erupted from its subducted N-S striking spreading ridge through a slab window. The eruptions stopped at 32 Ma, likely due to the Pacific plate flat-slab subducting from the south beneath this spreading ridge. At 28 Ma, magmatism started again to the east; indicating a major shift to the east of this "refusing to die" spreading ridge. The captured Yakutat plate has also been subducting since 63 Ma to the WSW. It started to change to WSW flat-slab subduction at 32 Ma, which stopped all subduction magmatism in W and SW Alaska by 22 Ma. The Yakutat plate subduction has again increased with the impact/joining of the coastal Yakutat terrane from the ESE about 5 Ma, resulting in the Cook Inlet Quaternary volcanism of southcentral Alaska. During the 1964 Alaska earthquake, sudden movements along the southcentral Alaska thrust faults between the Yakutat plate and the Pacific plate occurred. Specifically, the movements consisted of the Pacific plate moving NNW under the buried Yakutat plate and of the coastal Yakutat terrane, which is considered part of the Yakutat plate, thrusting WSW onto the Pacific plate. These were the two main sources of energy release for the E part of this earthquake. Only limited movement between the Yakutat plate and the North American plate occurred during this 1964 earthquake event. Buried paleopeat age dates indicate the thrust boundary between the Yakutat plate and North American plate will move in about 230 years, resulting in a more "continental" type megathrust earthquake for southcentral Alaska. There are, therefore, at least two different types of megathrust earthquakes occurring in southcentral Alaska: the more oceanic 1964 type and the more continental type. In addition, large "active" WSW oriented strike-slip faults are recognized in the Yakutat plate, called slice faults, which represent another earthquake hazard for the region. These slice faults also indicate important oil/gas and mineral resource locations.

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Section: The "Yak" Part Of the Yakutat Platementioning

confidence: 76%

“…It has been argued to be an oceanic plateau that has docked against NA and then move N. Most likely, yak is the remains of an inactive PAC-KULA ridge that did not subduct under Alaska during the Eocene-Oligocene when the rest of the KULA-PAC ridge did. Relative to NA, yak is moving 5 cm/yr NNW [5,32,33] at its E end (Fig. 1).…”

Section: David Publishingmentioning

confidence: 99%

The Active Yakutat (Kula?) Plate and Its Southcentral Alaska Megathrust and Intraplate Earthquakes

Reeder¹

2016

JEASE

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“…4.3.1) (Fletcher and Freymueller, 1999). This high convergence rate is expressed by high seismicity between Prince William Sound and the Alaska panhandle, which has generated some of the largest earthquakes including the M 9.2 Prince William Sound earthquake in 1964 (e.g.…”

Section: The St Elias Mountain Rangementioning

confidence: 99%

Seismic and non-seismic influences on coastal change in Alaska--Fieldtrip guide and conference abstracts, 5th International Conference of IGCP 588

Barlow¹,

Koehler²

2015

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“…The 1973 Cross Sound earthquake sequence, however, suggests that at least the southeastern end of the Transition fault zone is seismogenic (DOSER and LOMAS, 2000). GPS/Geodesy studies (FLETCHER and FREYMUELLER, 1999) suggest that $ 20 mm/yr of convergence must occur offshore of the Yakutat region, most likely upon the Transition fault zone. Plate motion analysis by PAVLIS et al (2004) indicates that 10 to 30 mm/yr of convergence must be accommodated across the Transition fault zone and/or the Yakutat foothills.…”

Section: Yakutat Regionmentioning

confidence: 99%

“…2), which marks the southern edge of the Yakutat block, in regional tectonics is also debated. BRUNS (1985) suggests the Transition fault zone has not been active since Miocene, but seismological (e.g., PE´REZ and JACOB, 1980;DOSER and LOMAS, 2000), GPS/ geodesy studies (FLETCHER and FREYMUELLER, 1999) and plate motion analysis suggest at least parts of the fault zone may currently be active. This complex region is the site of two great earthquakes occurring in 1899.…”

Section: Introductionmentioning

confidence: 99%

Relocations of Earthquakes (1899–1917) in South-Central Alaska

Doser

2006

Pure appl. geophys.

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I have relocated 18 earthquakes occurring in the south-central Alaska region between 1899 and 1917 using a bootstrap relocation technique. Locations of events within the Yakutat region suggest that the 1899 sequence began on 4 September with a M S = 7.9 event within the area of the Pamplona fault zone/western Transition fault zone, rupturing the western portion of the North American/Pacific plate interface. A M S = 7.4 event on 10 September appears to have ruptured the offshore portion of the plate interface to the east of the 4 September event. This was followed by a M S = 8.0 event that likely ruptured the onshore and down-dip portion of the plate interface. A M S = 7.0 event in 1908 may have ruptured a small portion of the plate interface between the 4 September and 10 September events. Events occurring between 1911 and 1916 in the Prince William Sound region appear to be slab events occurring in similar locations to more recent seismicity. Within the Kodiak region the 1900 earthquake of M S = 7.7 has a location consistent with the rupture of the Kodiak asperity which also ruptured during the 1964 great Alaska earthquake. Other large magnitude Kodiak events appear to be associated with regions of recent seismicity, including the Karluk Lake area of southwestern Kodiak Island and the Albatross Basin located offshore southeast of Kodiak Island. Space-time seismicity patterns since 1899 indicate that magnitude 6 to7 events have occurred with regularity in the Kodiak Island region; that there has been a lack of magnitude ‡ 6 events in the Prince William Sound region since 1964, and that the Yakutat region has remained notably quiescent at the magnitude ‡ 6 level.

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New GPS constraints on the motion of the Yakutat Block

Cited by 71 publications

References 18 publications

The Active Yakutat (Kula?) Plate and Its Southcentral Alaska Megathrust and Intraplate Earthquakes

The Active Yakutat (Kula?) Plate and Its Southcentral Alaska Megathrust and Intraplate Earthquakes

Seismic and non-seismic influences on coastal change in Alaska--Fieldtrip guide and conference abstracts, 5th International Conference of IGCP 588

Relocations of Earthquakes (1899–1917) in South-Central Alaska

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