The 1964 Prince William Sound earthquake: Joint inversion of tsunami and geodetic data

Johnson, Jodi; Satake, Kenji; Holdahl, Sanford R.; Sauber, Jeanne

doi:10.1029/95jb02806

Cited by 180 publications

(193 citation statements)

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“…West of Montague Island, the subducting Yakutat slab is absent and the Pacific Plate subducts directly beneath the North American plate [e.g., Brocher et al, 1994;EberhartPhillips et al, 2006]. The PWS asperity, defined as a region of high moment release [e.g., Lay et al, 1982;Scholz and Campos, 2012], was centered beneath the southwest end of Montague Island near a prominent magnetic high that defines the western boundary of the subducted Yakutat terrane (Figure 1) [Bruns, 1983;Griscom and Sauer, 1990;Brocher et al;1994;Johnson et al, 1996;Zweck et al, 2002;Eberhart-Phillips et al, 2006].…”

Section: Introductionmentioning

confidence: 99%

“…The earthquake rupture extended over an area approximately 800 km long by 250 km wide and generated tsunamis that devastated local communities across southern Alaska and damaged distant communities along the North American coast (Figure 1) [Plafker, 1969]. The earthquake initiated beneath the area immediately north of Prince William Sound (PWS) but ruptured across a region of low seismic coupling to activate a second asperity near Kodiak Island [e.g., Plafker, 1969;Christensen and Beck, 1994;Johnson et al, 1996;Zweck et al, 2002;Suito and Freymueller, 2009]. Here we examine deformation of the young sediment apron that lies above this subduction zone system to document the cumulative slip distribution for earthquakes over the past 10-15 kyr.…”

Section: Introductionmentioning

confidence: 99%

“…[3] The 1964 rupture had two high moment release areas with about 21 m of slip beneath PWS and 15 m of slip near Kodiak Island [Johnson et al, 1996]. The megathrust beneath PWS is the contact between the subducting Yakutat terrane and the overlying accretionary complex, referred to as the Prince William terrane [Brocher et al, 1994].…”

Section: Introductionmentioning

confidence: 99%

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Megathrust splay faults at the focus of the Prince William Sound asperity, Alaska

et al. 2013

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[1] High-resolution sparker and crustal-scale air gun seismic reflection data, coupled with repeat bathymetric surveys, document a region of repeated coseismic uplift on the portion of the Alaska subduction zone that ruptured in 1964. This area defines the western limit of Prince William Sound. Differencing of vintage and modern bathymetric surveys shows that the region of greatest uplift related to the 1964 Great Alaska earthquake was focused along a series of subparallel faults beneath Prince William Sound and the adjacent Gulf of Alaska shelf. Bathymetric differencing indicates that 12 m of coseismic uplift occurred along two faults that reached the seafloor as submarine terraces on the Cape Cleare bank southwest of Montague Island. Sparker seismic reflection data provide cumulative Holocene slip estimates as high as 9 mm/yr along a series of splay thrust faults within both the inner wedge and transition zone of the accretionary prism. Crustal seismic data show that these megathrust splay faults root separately into the subduction zone décollement. Splay fault divergence from this megathrust correlates with changes in midcrustal seismic velocity and magnetic susceptibility values, best explained by duplexing of the subducted Yakutat terrane rocks above Pacific plate rocks along the trailing edge of the Yakutat terrane. Although each splay fault is capable of independent motion, we conclude that the identified splay faults rupture in a similar pattern during successive megathrust earthquakes and that the region of greatest seismic coupling has remained consistent throughout the Holocene.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Megathrust splay faults at the focus of the Prince William Sound asperity, Alaska

et al. 2013

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“…Tsunamigenic-earthquake sources from the AleutianAlaska margin include earthquakes in 1957, 1964, and 1965(e.g. Johnson and Satake, 1993Johnson et al, 1994Johnson et al, , 1996Wesson et al, 2007).…”

Section: Tsunamigenic-earthquake Scenarios and Fault Modelsmentioning

confidence: 99%

Tsunami hazard potential for the equatorial southwestern Pacific atolls of Tokelau from scenario-based simulations

Orpin

Rickard

Gerring

et al. 2016

Nat. Hazards Earth Syst. Sci.

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Abstract. Devastating tsunami over the last decade have significantly heightened awareness of the potential consequences and vulnerability of low-lying Pacific islands and coastal regions. Our appraisal of the potential tsunami hazard for the atolls of the Tokelau Islands is based on a tsunami source-propagation-inundation model using Gerris Flow Solver, adapted from the companion study by Lamarche et al. (2015) for the islands of Wallis and Futuna. We assess whether there is potential for tsunami flooding on any of the village islets from a selection of 14 earthquake-source experiments. These earthquake sources are primarily based on the largest Pacific earthquakes of M w ≥ 8.1 since 1950 and other large credible sources of tsunami that may impact Tokelau. Earthquake-source location and moment magnitude are related to tsunami-wave amplitudes and tsunami flood depths simulated for each of the three atolls of Tokelau. This approach yields instructive results for a community advisory but is not intended to be fully deterministic. Rather, the underlying aim is to identify credible sources that present the greatest potential to trigger an emergency response.Results from our modelling show that wave fields are channelled by the bathymetry of the Pacific basin in such a way that the swathes of the highest waves sweep immediately northeast of the Tokelau Islands. Our limited simulations suggest that trans-Pacific tsunami from distant earthquake sources to the north of Tokelau pose the most significant inundation threat. In particular, our assumed worst-case scenario for the Kuril Trench generated maximum modelledwave amplitudes in excess of 1 m, which may last a few hours and include several wave trains. Other sources can impact specific sectors of the atolls, particularly distant earthquakes from Chile and Peru, and regional earthquake sources to the south. Flooding is dependent on the wave orientation and direct alignment to the incoming tsunami.Our "worst-case" tsunami simulations of the Tokelau Islands suggest that dry areas remain around the villages, which are typically built on a high islet. Consistent with the oral history of little or no perceived tsunami threat, simulations from the recent Tohoku and Chile earthquake sources suggest only limited flooding around low-lying islets of the atoll. Where potential tsunami flooding is inferred from the modelling, recommended minimum evacuation heights above local sea level are compiled, with particular attention paid to variations in tsunami flood depth around the atolls, subdivided into directional quadrants around each atoll. However, complex wave behaviours around the atolls, islets, tidal channels and within the lagoons are also observed in our simulations. Wave amplitudes within the lagoons may exceed 50 cm, increasing any inundation and potential hazards on the inner shoreline of the atolls, which in turn may influence evacuation strategies. Our study shows that indicative simulation studies can be achieved even with only basic field information. In part, this ...

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“…One remarkable exception to this was the Alaskan earthquake of 1964, for which the presence of Montague and Middleton Islands between the Alaskan coast and the Aleutian Trench provided unique land-based observations of slip on "splay faults" (see , e.g. Figure lb) which branch upward from the plate boundary [Plafker, 1972;Johnson et al, 1996]. The potential for rupture to partition along such splay faults may be an important factor in assessing the seismic and tsunami risk associated with subduction zone earthquakes [Fukao, 1979].…”

Section: Introductionmentioning

confidence: 99%

Possible splay fault slip during the 1946 Nankai earthquake

Cummins¹,

Kaneda²

2000

Geophysical Research Letters

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Abstract. This paper considers seafloor deformation associated with the 1946 Nankai earthquake, which occurred in the Nankai Trough subduction zone off the coast of southwest Japan. We note that recent high-resolution determinations of the slip distribution, assumed to be confined to the plate boundary, result in a pronounced maximum in seafloor displacement midway between the coast of Shikoku and the trough axis. We show that this feature could be due to slip on a splay fault rather than the plate boundary. Such a model for the western part of the slip distribution is able to account for the main features of the tsunamigenic seafloor deformation obtained in previous studies, with a maximum slip consistent with the plate convergent rate and history of earthquake recurrence at the Nankai Trough.

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The 1964 Prince William Sound earthquake: Joint inversion of tsunami and geodetic data

Cited by 180 publications

References 27 publications

Megathrust splay faults at the focus of the Prince William Sound asperity, Alaska

Megathrust splay faults at the focus of the Prince William Sound asperity, Alaska

Tsunami hazard potential for the equatorial southwestern Pacific atolls of Tokelau from scenario-based simulations

Possible splay fault slip during the 1946 Nankai earthquake

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