Deformed submarine terraces in Puget Sound, Pacific Northwest, indicate only one M >~7.5 earthquake on the Seattle fault zone in the past 11,000 yr
Geology
Links
- More information: Publisher Index Page (via DOI)
- Download citation as: RIS | Dublin Core
Abstract
Submerged marine terraces in Puget Sound, deformed across the Seattle fault zone (SFZ), indicate that only one earthquake as large as M~7.5 has occurred in at least the past 11 kyr. Previous paleoseismic studies document a M~7.5 earthquake between 923–4 CE, which uplifted coastal marine terraces by as much as 8 m. We demonstrate that this earthquake was the only such event since ~11 ka by mapping and quantifying deformation of older marine terraces, now submerged in Puget Sound. The submerged terraces, attributed to a late-glacial sea-level lowstand, record both glacial isostatic rebound and tectonic deformation. Vertical offset of the ~11 ka terraces within the SFZ is comparable to that of the marine terraces uplifted in 923 CE, implying no additional large (M>~7.5) earthquake on the SFZ since ~11 ka. This result implies a longer recurrence interval than current hazard estimates, which assumes recurrence of M>7.1 events every 5 kyr. Our mapping of SFZ deformation since ~11 ka also supports fault segmentation and contiguous block uplift between the Seattle and Tacoma fault zones.
Suggested Citation
Davis, E.J., Crider, J.G., Haugerud, R.A., Roland, E., and Moore, G., 2026, Deformed submarine terraces in Puget Sound, Pacific Northwest, indicate only one M >~7.5 earthquake on the Seattle fault zone in the past 11,000 yr: Geology, v. 54, no. 6, p. 495-500, https://doi.org/10.1130/G53496.1.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Deformed submarine terraces in Puget Sound, Pacific Northwest, indicate only one M >~7.5 earthquake on the Seattle fault zone in the past 11,000 yr |
| Series title | Geology |
| DOI | 10.1130/G53496.1 |
| Volume | 54 |
| Issue | 6 |
| Publication Date | February 27, 2026 |
| Year Published | 2026 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Earthquake Science Center |
| Description | 6 p. |
| First page | 495 |
| Last page | 500 |
| Country | United States |
| State | Washington |
| Other Geospatial | Puget Sound |