4 Results
4.1 Multibeam bathymetry and seismic profiles offshore Icy Point
As it approaches Icy Point from the south, the final 50 km of the Queen
Charlotte fault is a subtle, straight seafloor lineament and exhibits no
significant bends or steps along strike (Brothers et al., 2020). This
section of the fault adjoins the hypocenter of the 1958 Fairweather
earthquake and may have initiated the rupture that propagated
northwestward onto the Fairweather fault. Although the fault cuts late
Holocene basin fill deposited to the east in Palma Bay, the western side
of the fault is characterized by elevated topography for
>50 km south of Icy Point. Within 10 km of Icy Point,
seafloor bathymetry (Figure 2c) and seismic reflection profiles (Figure
5) show contractional structures that underlie the elevated topography
west of the Queen Charlotte fault. The vertical expression of the fault
ends within ~1 km offshore Icy Point where it steps 3 km
east to the primary strand of the Fairweather fault. Seismic profiles,
described next, suggest that the Queen Charlotte fault may bend
~10° to the west and merge with a shallow, 25°
east-dipping reverse fault aligned with the Finger Glacier fault mapped
onshore (Figure 2c). Offshore, the east-dipping reverse fault forms an
up-to-the-northeast scarp that wraps around the southwestern flank of
Icy Point; onshore the Finger Glacier fault vertically offsets Terrace B
(Hmt-B) and an alluvial fan (Hf) deposited by the Finger Glacier outwash
stream (Figure 4). No lateral offset on the Finger Glacier fault has
been documented.