Earthquake-induced sediment failures on a 0.25° slope, Klamath River delta, California

Abstract

Research Article| October 01, 1982 Earthquake-induced sediment failures on a 0.25° slope, Klamath River delta, California Michael E. Field; Michael E. Field 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar James V. Gardner; James V. Gardner 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Anne E. Jennings; Anne E. Jennings 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Brian D. Edwards Brian D. Edwards 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information Michael E. Field 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 James V. Gardner 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Anne E. Jennings 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Brian D. Edwards 1U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1982) 10 (10): 542–546. https://doi.org/10.1130/0091-7613(1982)10<542:ESFOAS>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Michael E. Field, James V. Gardner, Anne E. Jennings, Brian D. Edwards; Earthquake-induced sediment failures on a 0.25° slope, Klamath River delta, California. Geology 1982;; 10 (10): 542–546. doi: https://doi.org/10.1130/0091-7613(1982)10<542:ESFOAS>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract On November 8, 1980, a major earthquake (magnitude 6.5 to 7.2) occurred 60 km off the coast of northern California. A survey of the area using high-resolution seismic-reflection and side-scan sonar equipment revealed the presence of extensive sediment failure and flows in a zone about 1 km wide and 20 km long that trends parallel to the shelf on the very gently sloping (< 0.25°) Klamath River delta. The failure zone is marked by a well-defined terrace that slopes seaward at about 0.02c and a prominent 1- to 2-m high, seaward-facing toe scarp on the outer margin of the terrace. This toe scarp is sinuous, appears to be nearly continuous for a distance of 20 km, and closely parallels the 60-m isobath. Evidence indicates that the toe scarp is the terminus of lateral spreads and lobes of sediment flows. Side-scan sonar records show evidence of gas vents and small (10 × 3 × 0.5 m high) pressure ridges formed seaward of and parallel to the sediment flow scarp. Indicators of liquefaction (sand boils and collapse craters) are present on the sediment flow terrace. Extensive sediment failure occurred on a sea-floor slope of less than 0.25°, and we can unequivocally pinpoint the cause as an earthquake of known location, magnitude, and time. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.