Focused exhumation along megathrust splay faults in Prince William Sound, Alaska

Haeussler, Peter J.; Armstrong, Phillip A.; Liberty, Lee M.; Ferguson, Kelly M.; Finn, S.; Arkle, Jeannette C; Pratt, Thomas L.

doi:10.1016/j.quascirev.2014.10.013

Cited by 27 publications

(55 citation statements)

References 46 publications

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“…Although the entire PWS region was uplifted in 1964, geodetic data show that central PWS has been gradually subsiding since the earthquake, consistent with a locked megathrust interface (Freymueller et al, 2008). The relatively moderate interseismic subsidence contrasts with the estimated millennial-scale exhumation rates of greater than 1 mm=yr recorded with thermochronology methods for rocks in the hanging wall of the Patton Bay megathrust splay fault (Arkle et al, 2013;Ferguson et al, 2015;Haeussler et al, 2015). Hence, coseismic uplift rates have outpaced interseismic subsidence rates in the hanging wall of these splay faults for PWS throughout the Quaternary record.…”

Section: Tectonic Setting and Earthquake Historymentioning

confidence: 78%

“…Crustalscale seismic refraction and reflection data provide evidence for underthrusting or duplexing of the Pacific plate beneath the Yakutat terrane, and for splay faults emerging at depth from a regional decollement (Brocher et al, 1994;Fruehn et al, 1999;Fuis et al, 2008;Liberty et al, 2013;Haeussler et al, 2015). Modeling of magnetic data provides compelling evidence that the trailing edge of the Yakutat terrane, marked by the slope magnetic anomaly (SMA), lies between Montague and Middleton Islands ( Fig.…”

Section: Tectonic Setting and Earthquake Historymentioning

confidence: 95%

“…Damage from ground shaking was widespread, and the associated tsunamis inundated coastline infrastructure as far away as northern California. Local tsunamis damaged the Alaska (Wilson and Hults, 2012;Liberty et al, 2013;Haeussler et al, 2015). Faults that slipped during the 1964 Great Alaska earthquake include the Patton Bay fault (PBF), Hanning Bay fault (HBF), and Cape Cleare fault (CCF).…”

Section: The 1964 Great Alaska Earthquakementioning

confidence: 99%

“…Brocher et al (1994) interpreted refraction data from this survey that utilized PWS island-based seismometers. Fruehn et al (1999), Liberty et al (2013), and Haeussler et al (2015) have published TACT reflection data that highlight plate boundary and splay fault geometries. We reprocessed the 7700-cubic-inch, 240-channel TACT-D segment of the reflection seismic profile within PWS for this study.…”

Section: Data Sourcesmentioning

confidence: 99%

“…Splay faults that extend from the subduction interface to the seafloor or land on the Alaska continental shelf accommodate the bulk of upper-plate coseismic motion for large earthquakes in the region, and these thrust faults strongly influence island formation in the PWS area (e.g., Plafker, 1969;Liberty et al, 2013;Haeussler et al, 2015). The only documented surface ruptures from the 1964 earthquake occurred on Montague Island in southwest PWS and on the adjacent Gulf of Alaska seafloor ( Fig.…”

Section: Introductionmentioning

confidence: 99%

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Landslides and Megathrust Splay Faults Captured by the Late Holocene Sediment Record of Eastern Prince William Sound, Alaska

Finn¹,

Liberty²,

Haeussler³

et al. 2015

Bulletin of the Seismological Society of America

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We present new marine seismic-reflection profiles and bathymetric maps to characterize Holocene depositional patterns, submarine landslides, and active faults beneath eastern and central Prince William Sound (PWS), Alaska, which is the eastern rupture patch of the 1964 M w 9.2 earthquake. We show evidence that submarine landslides, many of which are likely earthquake triggered, repeatedly released along the southern margin of Orca Bay in eastern PWS. We document motion on reverse faults during the 1964 Great Alaska earthquake and estimate late Holocene slip rates for these growth faults, which splay from the subduction zone megathrust. Regional bathymetric lineations help define the faults that extend 40-70 km in length, some of which show slip rates as great as 3:75 mm=yr. We infer that faults mapped below eastern PWS connect to faults mapped beneath central PWS and possibly onto the Alaska mainland via an en echelon style of faulting. Moderate (M w > 4) upper-plate earthquakes since 1964 give rise to the possibility that these faults may rupture independently to potentially generate M w 7-8 earthquakes, and that these earthquakes could damage local infrastructure from ground shaking. Submarine landslides, regardless of the source of initiation, could generate local tsunamis to produce large run-ups along nearby shorelines. In a more general sense, the PWS area shows that faults that splay from the underlying plate boundary present proximal, perhaps independent seismic sources within the accretionary prism, creating a broad zone of potential surface rupture that can extend inland 150 km or more from subduction zone trenches.

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Section: Tectonic Setting and Earthquake Historymentioning

confidence: 78%

Section: Tectonic Setting and Earthquake Historymentioning

confidence: 95%

Section: The 1964 Great Alaska Earthquakementioning

confidence: 99%

Section: Data Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Landslides and Megathrust Splay Faults Captured by the Late Holocene Sediment Record of Eastern Prince William Sound, Alaska

Finn¹,

Liberty²,

Haeussler³

et al. 2015

Bulletin of the Seismological Society of America

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Back-analysis of the paraglacial slope failure at Grewingk Glacier and Lake, Alaska

Lemaire,

Dufresne,

Hamdi

et al. 2023

Landslides

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The relationship between rock-slope failure and glacier retreat is complex, and paraglacial failures often lack clearly identified triggers. To better understand the role of glacier retreat in rock-slope failures, we analysed the processes that led to the October 1967 Grewingk landslide in Kachemak Bay State Park on the Kenai Peninsula, Southcentral Alaska. The rock material collapsed onto the glacier toe and into its pro-glacial lake and produced a tsunami wave that swept the outwash plain. On the day of the failure, rainfall and snowmelt were well within normal ranges, and seismic records show no significant shaking. Three years prior to the 1967 failure, the slope withstood the second largest earthquake ever recorded (Great Alaskan earthquake, MW 9.2). We reassessed the volume of the failure by differencing pre- and post-digital terrain models and found a value of 20–24 × 106 m3, which is four times smaller than a previous estimate. The back analysis of the Grewingk landslide is based on remote sensing data and field measurements including aerial satellite image analysis, detailed surveying and understanding of the structural geology, a kinematic analysis, and runout modelling. Our research provides an example of a major paraglacial failure that lacks an obvious trigger and points to several geological factors and changing environmental conditions that likely promote such failures. This study further indicates that the Grewingk landslide, pre-conditioned by the geometry of faults and joints, may have reached a critical stability state due to internal processes and the potential combined effects of seismic activity and glacier retreat prior to the collapse.

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Practical approaches to maximizing the resolution of sparker seismic reflection data

et al. 2018

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Focused exhumation along megathrust splay faults in Prince William Sound, Alaska

Cited by 27 publications

References 46 publications

Landslides and Megathrust Splay Faults Captured by the Late Holocene Sediment Record of Eastern Prince William Sound, Alaska

Landslides and Megathrust Splay Faults Captured by the Late Holocene Sediment Record of Eastern Prince William Sound, Alaska

Back-analysis of the paraglacial slope failure at Grewingk Glacier and Lake, Alaska

Practical approaches to maximizing the resolution of sparker seismic reflection data

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