Basement Structure and Styles of Active Tectonic Deformation in Central Interior Alaska

Dixit, N. C.; Hanks, Catherine L.

doi:10.3390/geosciences11030127

Cited by 3 publications

(2 citation statements)

References 39 publications

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“…Previous studies on the TB report depths of 1.5 km to the basement (Dixit & Hanks, 2021; Trop & Ridgway, 2007). The high velocity in the basement can be explained by the Yukon–Tanana Terrane schist underlying the basin (Dixit & Hanks, 2021).…”

Section: Discussionmentioning

confidence: 95%

“…The high velocity in the basement can be explained by the Yukon–Tanana Terrane schist underlying the basin (Dixit & Hanks, 2021). Our profile (Figure 1b) does not extend north beyond the town of Nenana into the Nenana basin (NB), where sediments up to 8 km deep have been interpreted from borehole data and seismic reflection data in the NB (Dixit & Hanks, 2021; Van Kooten et al., 2012).…”

Section: Discussionmentioning

confidence: 99%

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The Crustal Magmatic Structure Beneath the Denali Volcanic Gap Imaged by a Dense Linear Seismic Array

Rabade,

Lin,

Tape

et al. 2023

JGR Solid Earth

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The crustal structure in south‐central Alaska has been influenced by terrane accretion, flat slab subduction, and a modern strike‐slip fault system. Within the active subduction system, the presence of the Denali Volcanic Gap (DVG), a ∼400 km region separating the active volcanism of the Aleutian Arc to the west and the Wrangell volcanoes to the east, remains enigmatic. To better understand the regional tectonics and the nature of the volcanic gap, we deployed a month‐long north‐south linear geophone array of 306 stations with an interstation distance of 1 km across the Alaska Range. By calculating multi‐component noise cross‐correlation and jointly inverting Rayleigh wave phase velocity and ellipticity across the array, we construct a 2‐D shear wave velocity model along the transect down to ∼16 km depth. In the shallow crust, we observe low‐velocity structures associated with sedimentary basins and image the Denali fault as a narrow localized low‐velocity anomaly extending to at least 12 km depth. About 12 km, below the fold and thrust fault system in the northern flank of the Alaska Range, we observe a prominent low‐velocity zone with more than 15% velocity reduction. Our velocity model is consistent with known geological features and reveals a previously unknown low‐velocity zone that we interpret as a magmatic feature. Based on this feature's spatial relationship to the Buzzard Creek and Jumbo Dome volcanoes and the location above the subducting Pacific Plate, we interpret the low‐velocity zone as a previously unknown subduction‐related crustal magma reservoir located beneath the DVG.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

The Crustal Magmatic Structure Beneath the Denali Volcanic Gap Imaged by a Dense Linear Seismic Array

Rabade,

Lin,

Tape

et al. 2023

JGR Solid Earth

View full text Add to dashboard Cite

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Basement structure of the Northern Foothills Fold and Thrust Belt and southern Fairbanks and Salcha, Alaska Seismic zones and their relation to large (M ≥ 6) earthquakes

Doser

Baker²

2023

Tectonophysics

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Seismic Response of Nenana Sedimentary Basin, Central Alaska

Smith

Tape

Tsai

2022

Bulletin of the Seismological Society of America

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Nenana basin in central Alaska is a long (90 km), narrow (12 km), and deep (7 km) sedimentary basin aligned with an active fault zone producing Mw≥6 earthquakes. From 2015 to 2019, 13 broadband seismic stations were deployed in the region as part of the Fault Locations and Alaska Tectonics from Seismicity project. These stations recorded a wide range of earthquakes, including Mw 3–4 directly below the basin as well as several regional earthquakes Mw>6. These 43 local and regional earthquakes, in addition to five teleseismic events and continuously recorded ambient noise, provide a data set that we use to quantify the response of Nenana basin to the seismic wavefield. We calculate spectral ratios between each station and a bedrock reference station for 48 earthquakes. We find amplification of 11–14 dB (amplification ratio 3.5–5.0) for low frequencies (0.1–0.5 Hz), and 8–15 dB (amplification ratio 2.5–5.6) for high frequencies (0.5–4.0 Hz) on the vertical component. At low frequencies, amplification of the earthquake wavefield agrees well with amplification of seismic noise, with both data sets exhibiting stronger amplification on the horizontal components, in comparison with the vertical component. Furthermore, stations overlying the deeper part of the basin exhibit stronger amplification, whereas stations at the margin of the basin exhibit minimal low-frequency amplification. At higher frequencies, amplification occurs at both deeper basin stations and also marginal basin stations. Our study establishes a catalog of diverse events for future theoretical and numerical studies that can use Nenana basin to better understand the complex influence of sedimentary basins on the seismic wavefield.

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Basement Structure and Styles of Active Tectonic Deformation in Central Interior Alaska

Cited by 3 publications

References 39 publications

The Crustal Magmatic Structure Beneath the Denali Volcanic Gap Imaged by a Dense Linear Seismic Array

The Crustal Magmatic Structure Beneath the Denali Volcanic Gap Imaged by a Dense Linear Seismic Array

Basement structure of the Northern Foothills Fold and Thrust Belt and southern Fairbanks and Salcha, Alaska Seismic zones and their relation to large (M ≥ 6) earthquakes

Seismic Response of Nenana Sedimentary Basin, Central Alaska

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