Crescent City Tsunami Deposits: Sand Mine Marsh, 1700 A.D. Cascadia subduction zone earthquake generated tsunami

I collected some cores in the Crescent City region. The sedimentary evidence of the 1700 A.D. Cascadia subduction zone earthquake and tsunami is preserved in these cores. Watch the video below.

Here is a composite of the two cores that I collected. The top of the core is on the left.

  • YT link for the embedded video below:
    Here is the Narrative for the above video:

  • What many interpret to be the sedimentary evidence of a Cascadia subduction zone earthquake generated tsunami. The earthquake probably happened in the early evening of January 26, 1700 A.D.
  • The tsunami deposit has been described by several researchers, beginning with Gary Carver and his graduate students.
  • Their report to Pacific Gas and Electric was submitted in 1998. They presented their findings of tsunami deposits in Humboldt and Del Norte Counties.
  • These gray literature results were later presented in a Pacific Cell Friends of the Pleistocene 2006 Field Trip Guidebook.
  • In 2011, Curt Petersen and his coauthors published these and more results. Here is a map from Petersen et al., 2011 showing the study area in the Crescent City region. Petersen and his coauthors collected sediment cores in three marshes: The Elk River Marsh, the Anchor Way Marsh, and the Sand Mine Marsh.
  • Here is a map of the Sand Mine Marsh area and sediment core correlation diagram for some of the cores plotted on the map. The tsunami deposit “TSL # 1” is interpreted as the 1700 AD tsunami deposit.
  • Here is a series of X-Ray images of one of these cores. The vertical axis is depth. The horizontal axis is the width of the core. Darker gray is less dense and lighter gray is denser. The thickest and most dense material is labeled TSL # 1.
  • This map shows the location of the Carver et al. (1998) cores in green. The location of the core that I present next in this video is displayed as a light blue dot and labeled 15-smw-01. This core is located in a similar location as the Petersen et al. (2011) cores cc18 and VB12.
  • Here are two cores that I collected at the same location. The core on the left is 60 mm in diameter, the core on the right is 30 mm in diameter.
  • Now we scroll from the top of the core, down section. The entire core section is plotted on the right as before.
  • Here is the top of the TSL # 1 deposit.
  • Here is the base of TSL # 1 deposit.
  • Here we see the entire TSL # 1 deposit. Note the sharp contact at the base of this sandy deposit.
Category(s): cascadia, College Redwoods, earthquake, education, geology, HSU, plate tectonics, subduction, tsunami

One Response to Crescent City Tsunami Deposits: Sand Mine Marsh, 1700 A.D. Cascadia subduction zone earthquake generated tsunami

  1. Wonder what it was like in Samoa on that day.

2 Responses in other blogs/articles

  1. […] I recently collected a core with a thick sandy deposit that is hypothesized to be the sedimentary deposit that was the result of tsunami deposition following the 1700 A.D. Cascadia subduction zone earthquake. Here is my post about that core. […]

  2. […] I recently collected a core with a thick sandy deposit that is hypothesized to be the sedimentary deposit that was the result of tsunami deposition following the 1700 A.D. Cascadia subduction zone earthquake. Here is my post about that core. […]

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