Geology and geologic hazards of offshore Eel River basin, northern California continental margin

Writing a Rosetta Stone: Insights into Continental‐Margin Sedimentary Processes and Strata

“…The largest feature on the Eel margin (~90 km 2 ) with the outward appearance of failure is known as the 'Humboldt Slide' (Field et al, 1980), but its origin is controversial. It is found in an amphitheatre-like depression between 220-m and 650-m water depth (Fig.…”

“…The profiles suggest that the greatest failure was in the middle of the 'slide', and that it underwent a small amount of downslope translation with shallow rotation, creating gentle compression folds at its base. Deeper profiles show older deposits of similar character and imply a long history of such events (Field et al, 1980). The multibeam surveys also document many pockmarks, interpreted as evidence of gas escape from the seabed (Yun et al, 1999), and many erosive gullies on the rim of the feature (above 380-m water depth, see Fig.…”

Submarine landslides: Selected studies in the U.S. Exclusive Economic Zone

“…centrations of dissolved methane-rich gas were collected from within and upslope of the slide zone. Sources of information are as follows: gas hydrate zone ; gas hydrate samples (Brooks and others, 1991); gas anomalies (Field and others, 1980;Field and Kvenvolden, unpublished data); gas measurements (Field and Kvenvolden, 1987); and Humboldt Slide Zone (Field, Clarke, and White, 1980;Field, Gardner, and others, 1987;Lee and others, 1981).…”

Sonographs of submarine sediment failure caused by the 1980 earthquake off northern California

“…This Neogene alibi lower Quaternary sequence is truncated by a Pleistocene erosional unconformity and Overlain by undeformed seaward-dipping sediment of late Pleistocene and Holocene, age.' Off ~he' Klar0ath River, this upper Quaternary sediment attains a i.hi6kness of 20 to 50 m in water depths of 30 to 70 m [7]. The sediment unit is lobate in plan and presumably is derived largely from sediment delivered to the coast by the Klamath River, a major contributor of sediment to the northwestern U.S. Continental shelf.…”

“…The sediment unit is lobate in plan and presumably is derived largely from sediment delivered to the coast by the Klamath River, a major contributor of sediment to the northwestern U.S. Continental shelf. Principal surficial sediment types on the shelf are muddy sand shoreward of about the 60 L m isobath ~nd sandy-clayey silt from there seaward [7,8]. …”