A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska

Haeussler, Peter J.; Liberty, Lee M.; Finlayson, David P.; Geist, Eric L.; Labay, Keith A.; Byerly, Michael

doi:10.1016/j.epsl.2016.01.008

Cited by 32 publications

(25 citation statements)

References 29 publications

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“…Apart from the realization that MTDs are an important stratigraphic component of continental margins (they can reach ~70% of their total volume of sediments; Maslin et al, ; Moscardelli & Wood, ), this study has significant implications to, at least, four key aspects: (1) when accurately calculating the volumes of MTDs, a piece of information that is important to the modeling of sediment transport and distribution processes in deepwater margins; (2) when modeling tsunami height and distribution, as the initial volume of failed sediment (Text S1), together with water depth, initial sediment acceleration, sediment type, and slope gradient, are important parameters influencing the magnitude of landslide‐triggered tsunamis (Locat et al, ). Most published data, using only imaged volumes (Vm) for MTDs, have consistently returned modeled tsunami magnitudes that are lower than their witnessed heights, e.g., the 1998 Papua New Guinea (Synolakis et al, ), the 1929 Grand Banks (Fine et al, ), and the 1964 southern Alaska (Brothers et al, ) tsunamis. For example, the modeled height for the 1998 Papua New Guinea tsunami was 20%–50% lower than the values observed in the field (Synolakis et al, ), a result of systematic underestimations of the volume of MTDs associated with the tsunami; (3) deepwater cables can be disrupted by landslide‐generated turbidity currents (Carter et al, ; Pope et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…(2) when modeling tsunami height and distribution, as the initial volume of failed sediment (Text S1), together with water depth, initial sediment acceleration, sediment type, and slope gradient, are important parameters influencing the magnitude of landslide-triggered tsunamis (Locat et al, 2004). Most published data, using only imaged volumes (Vm) for MTDs, have consistently returned modeled tsunami magnitudes that are lower than their witnessed heights, e.g., the 1998 Papua New Guinea (Synolakis et al, 2002), the 1929 Grand Banks (Fine et al, 2005), and the 1964 southern Alaska (Brothers et al, 2016) tsunamis. For example, the modeled height for the 1998 Papua New Guinea tsunami was 20%-50% lower than the values observed in the field (Synolakis et al, 2002), a result of systematic underestimations of the volume of MTDs associated with the tsunami; (3) deepwater cables can be disrupted by landslide-generated turbidity currents (Carter et al, 2012;Pope et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

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True Volumes of Slope Failure Estimated From a Quaternary Mass‐Transport Deposit in the Northern South China Sea

Sun

Alves

et al. 2018

Geophysical Research Letters

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Submarine slope failure can mobilize large amounts of seafloor sediment, as shown in varied offshore locations around the world. Submarine landslide volumes are usually estimated by mapping their tops and bases on seismic data. However, two essential components of the total volume of failed sediments are overlooked in most estimates: (a) the volume of subseismic turbidites generated during slope failure and (b) the volume of shear compaction occurring during the emplacement of failed sediment. In this study, the true volume of a large submarine landslide in the northern South China Sea is estimated using seismic, multibeam bathymetry and Ocean Drilling Program/Integrated Ocean Drilling Program well data. The submarine landslide was evacuated on the continental slope and deposited in an ocean basin connected to the slope through a narrow moat. This particular character of the sea floor provides an opportunity to estimate the amount of strata remobilized by slope instability. The imaged volume of the studied landslide is ~1035 ± 64 km3, ~406 ± 28 km3 on the slope and ~629 ± 36 km3 in the ocean basin. The volume of subseismic turbidites is ~86 km3 (median value), and the volume of shear compaction is ~100 km3, which are ~8.6% and ~9.7% of the landslide volume imaged on seismic data, respectively. This study highlights that the original volume of the failed sediments is significantly larger than that estimated using seismic and bathymetric data. Volume loss related to the generation of landslide‐related turbidites and shear compaction must be considered when estimating the total volume of failed strata in the submarine realm.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

True Volumes of Slope Failure Estimated From a Quaternary Mass‐Transport Deposit in the Northern South China Sea

Sun

Alves

et al. 2018

Geophysical Research Letters

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“…There are significant differences in the deposits of this STS landslide with purely submarine landslides in other Alaskan fjords (Table ; see Brothers et al, ; Haeussler et al, , ; Lee et al, , ; Parsons et al, ; Ryan et al, ). As discussed earlier, submarine landslide deposits tend to have a broad lobate front, in contrast to the more pointed front of the Taan Fiord deposit.…”

Section: Signature Of An Sts Landslide Discussionmentioning

confidence: 89%

“…The acoustic signature of the deposits is commonly transparent or chaotic with low amplitudes. Based on seismic images of submarine landslide deposits, previous studies have imaged erosion at the flow base and evidence that the slide volume grows through inclusion of sediment along the transport path (Aarseth et al, 1989;Brothers et al, 2016;Haeussler et al, 2007Haeussler et al, , 2013Hampton et al, 1996;Locat & Lee, 2002;Ryan et al, 2010).…”

Section: 1029/2018jf004608mentioning

confidence: 99%

Submarine Deposition of a Subaerial Landslide in Taan Fiord, Alaska

et al. 2018

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A large subaerial landslide entered Taan Fiord, Alaska, on 17 October 2015 producing a tsunami with runup to 193 m. We use LiDAR data to show the slide volume to be 76 + 3/−4 million cubic meters and that 51,000,000 m3 entered Taan Fiord. In 2016, we mapped the fjord with multibeam bathymetry and high‐resolution seismic data. Landslide and postlandslide deposits extend 6 km downfjord, are up to 70 ± 11 m thick, and have a total volume of ~147,000,000 m3. Seismic data image a blocky landslide unit and two units deposited immediately after the landslide. The blocky landslide unit is ~65,000,000 m3. We infer it consists dominantly of subaerially derived material and secondarily of fjord floor sediment. The overlying units are likely megaturbidites presumably deposited within minutes to days after the landslide. We infer that these deposits dominantly consist of fjord floor material mobilized and suspended as the slide entered and traveled downfjord. The lower postlandslide unit is up to 35 ± 6 m thick, and the upper unit is up to 12 ± 3 m thick. These deposits are distinctive and will leave a lasting record of the event. This subaerial‐to‐submarine landslide deposit is distinct from other submarine landslide deposits studied in Alaskan fjords because it has a much greater thickness, larger and more angular blocks, distinctive postlandslide megaturbidites, and a higher‐amplitude acoustic signature of the blocky deposit. The tight constraints on the landslide source and deposit volumes, topography, bathymetry, and tsunami runup heights and flow directions should make this a benchmark site for landslide‐tsunami models.

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“…The region of differential uplift is where tsunamis can be set into motion. A trans-Pacific tsunami resulting from slip on faults that splay from the megathrust were responsible for deaths across the eastern Pacific Ocean in 1964; however, local tsunamis arriving on mainland Alaska and key islands were also engendered from both tectonic and landslide sources (Plafker, 1969;Ryan et al, 2011;Haeussler et al, 2015;Brothers et al, 2016). Figure 2 delimits the Gulf of Alaska segments that have been proposed based largely from paleoseismic studies (Carver and Plafker, 2008;Briggs et al, 2014;Shennan et al, 2014;Kelsey et al, 2015).…”

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confidence: 99%

Earthquake Segment Boundaries and Tsunamigenic Faults of the Kodiak Segment, Alaska-Aleutian Subduction Zone

Ramos¹

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The final reading approval of the thesis was granted by Lee M. Liberty, M.S. Chair of the Supervisory Committee. The thesis was approved by the Graduate College. The northeast Kodiak segment boundary is defined by the subducting 58° fracture zone, which can be traced below the forearc using magnetic and gravitational fields.Subduction of this feature is expressed on post-1964 seismicity, is consistent with oblique shortening, and manifests itself within the upper plate as the Portlock Anticline.The southwest segment boundary marks the transition between the Kodiak and Semidi segments. It is shown to be a region that shifts from significant margin erosion to a region of imbricate thrusting and margin growth. These two zones are bound by fracture zone subduction. I furthermore independently constrain and compliment vii paleoseismological models of joint Kodiak and Semidi segment rupture by identifying and characterizing a through-going marine fault zone across this segment boundary.Finally, I revisit the source mechanisms for the local tsunami that inundated the Kodiak Islands as a result of the 1964 earthquake. I provide a new tsunamigenic source model that suggests discrete uplift of the Kodiak Islands shelf fault system and illuminate its along-strike rupture variability throughout the Holoecene epoch.My findings suggest segment boundaries across Kodiak have a clear geophysical expression and a multi-dataset approach is necessary to decipher tectonic controls on megathrust segmentation.

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A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska

Cited by 32 publications

References 29 publications

True Volumes of Slope Failure Estimated From a Quaternary Mass‐Transport Deposit in the Northern South China Sea

True Volumes of Slope Failure Estimated From a Quaternary Mass‐Transport Deposit in the Northern South China Sea

Submarine Deposition of a Subaerial Landslide in Taan Fiord, Alaska

Earthquake Segment Boundaries and Tsunamigenic Faults of the Kodiak Segment, Alaska-Aleutian Subduction Zone

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