ShakeMap Scenario Catalog for Selected Quaternary Active Faults in Washington State
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Description
Event Selection
These scenarios provide generalized realizations of potential shaking effects from possible future earthquakes on a select number of known Quaternary active faults in Washington State. Input parameters discussed below and in Table 1 were developed in collaboration with the Washington State Geological Survey (WGS).
Fault Selection
The 24 fault segments providing source parameters for the scenarios in this archive are a subset of active or potentially active faults in the state. Not all faults in each region capable of producing a large magnitude earthquake have an associated scenario in this archive. USGS and WGS scientists selected exemplary faults which may produce an earthquake of a high enough magnitude to damage human structures (a "major earthquake") and also have the best-defined fault parameters for the modeling process. The modeled faults are proximal to populated regions and critical infrastructure; they give planners and emergency managers examples of likely shaking during a major earthquake. They may also be used to project the level of damage during such earthquakes for planning purposes.
For all but the Mount St. Helens seismic zone, Toe Jam fault, and Latah fault, fault source geometries are from the 2023 National Seismic Hazard Model (NSHM) source model (Hatem et al., 2021). Table 1 provides additional references used for fault trace location and geometry not included in the 2023 NSHM source model. Multi-fault rupture scenarios were generated based on published scientific studies that consider multi-fault ruptures guided computation of more complex scenarios (e.g. Seattle fault zone/Saddle Mountain in Table 1).
Earthquake Parameters
Earthquake hypocenters originate in the center of each fault plane segment. Preferred magnitudes are estimated in Styron and Sherrod (2021); if this source provided no estimate, we applied empirical scaling relations in Wesnousky (2008) based on fault trace length (see Table 1).
Ground Motion Models
A weighted combination of ground motion models for reference rock conditions that is consistent with the 2018 version of the USGS national seismic hazard maps constrained the ground motion shaking intensity parameters for each modeled rupture. More details are available in the documentation for the 2014 update of the NSHM and in the metadata for each scenario.
We have employed the OpenQuake hazard library (Pagani et al., 2014) implementation of the ground motion models. OpenQuake hazardlib provides a broad range of well-tested open-source models.
The ground motion parameters in ShakeMap are converted from the average horizontal component, which is given by most ground motion models, to the peak horizontal component. This is necessary for consistency with real-time ShakeMaps. Additional details are discussed in this section of the ShakeMap manual (Worden et al., 2020).
| Scenario Name | Length (km) | Depth (km) | Slip Sense | Reference | Hypocenter Latitude | Hypocenter Longitude | Depth (km) | Moment Magnitude | Reference |
|---|---|---|---|---|---|---|---|---|---|
| Birch Bay fault | 23 | 15 | Reverse | Hatem et al. (2021) | 48.905 | -122.653 | 7.5 | 6.9 | Styron and Sherrod (2021) |
| Boulder Creek fault | 16 | 15 | Reverse | Hatem et al. (2021) | 48.875 | -122.078 | 7.5 | 6.6 | Styron and Sherrod (2021) |
| Canyon River - Saddle Mountain fault | 75 | 15 | Reverse | Hatem et al. (2021) | 47.418 | -123.181 | 7.5 | 7 | Styron and Sherrod (2021) |
| Darrington Devils fault | 80 | 15 | Reverse | Hatem et al. (2021) | 48.384 | -122.191 | 7.5 | 7.1 | Styron and Sherrod (2021) |
| Entiat Fault | 59 | 15 | Reverse | Hatem et al. (2021) | 47.687 | -120.573 | 7.5 | 7.1 | Wesnousky (2008) |
| Gales Creek fault | 56 | 15 | Strike-slip | Hatem et al. (2021) | 45.374 | -123.107 | 7.5 | 7.2 | Wesnousky (2008) |
| Horse Heaven Hills fault | 64 | 15 | Reverse | Hatem et al. (2021) | 46.121 | -119.943 | 7.5 | 7.2 | Wesnousky (2008) |
| Lake Creek - Boundary Creek - Sadie Creek fault | 52 | 15 | Strike-slip | Hatem et al. (2021) | 48.07 | -123.633 | 7.5 | 6.7 | Styron and Sherrod (2021) |
| Latah fault* | 29 | 15 | Strike-slip | Hamilton et al. (2004); Wicks et al. (2009) | 47.67 | -117.461 | 7.5 | 6.8 | Wesnousky (2008) |
| Manastash fault | 48 | 15 | Reverse | Hatem et al. (2021) | 46.794 | -120.664 | 7.5 | 7.1 | Wesnousky (2008) |
| Mount St. Helens Seismic zone** | 43 | 15 | Strike-slip | Waite and Moran (2009) | 46.229 | -122.213 | 7.5 | 7 | Wesnousky (2008) |
| Rattlesnake Mountain fault | 36 | 15 | Reverse | Hatem et al. (2021) | 47.532 | -121.916 | 7.5 | 6.9 | Wesnousky (2008) |
| Saddle Mountains fault | 91 | 15 | Reverse | Hatem et al. (2021) | 46.733 | -119.75 | 7.5 | 7 | Wesnousky (2008) |
| Seattle fault zone (frontal fault) | 71 | 15 | Reverse | Hatem et al. (2021) | 47.533 | -122.403 | 7.5 | 7.5 | Styron and Sherrod (2021) |
| Seattle fault zone/Saddle Mountain | 150 | 15 | Reverse | Hatem et al. (2021) | 47.533 | -122.403 | 7.5 | 7.8 | Black et al. (2023) |
| Spencer Canyon fault | 70 | 15 | Reverse | Hatem et al. (2021) | 47.773 | -120.051 | 7.5 | 7.2 | Wesnousky (2008) |
| Southern Whidbey Island fault | 170 | 15 | Reverse | Hatem et al. (2021) | 48.086 | -122.487 | 7.5 | 7.2 | Styron and Sherrod (2021) |
| Tacoma fault | 35 | 5 | Reverse | Hatem et al. (2021) | 47.412 | -122.739 | 7.5 | 7.1 | Styron and Sherrod (2021) |
| Seattle fault zone - Toe Jam fault | 53 | 15 | Reverse | Nelson et al. (2014); Pratt et al. (2015) | 47.599 | -122.509 | 2.5 | 6.8 | Styron and Sherrod (2021) |
| Topponish Ridge - Mill Creek fault | 57 | 15 | Reverse | Hatem et al. (2021) | 46.268 | -120.559 | 7.5 | 7.5 | Wesnousky (2008) |
| Utsalady Point East fault | 23 | 15 | Reverse | Hatem et al. (2021) | 48.328 | -122.611 | 7.5 | 6.7 | Styron and Sherrod (2021) |
| Utsalady Point West fault | 53 | 15 | Strike-slip | Hatem et al. (2021) | 48.375 | -123.112 | 7.5 | 6.7 | Styron and Sherrod (2021) |
| Wallula fault zone | 113 | 15 | Reverse | Hatem et al. (2021) | 46.103 | -119.1 | 7.5 | 7.1 | Wesnousky (2008) |
*Not included in the 2023 NSHM Source Model.
**Fault trace derived from seismicity.
References
- Black, B. A., Pearl, J. K., Pearson, C. L., Pringle, P. T., Frank, D. C., Page, M. T., ... & Sherrod, B. L. (2023). A multifault earthquake threat for the Seattle metropolitan region revealed by mass tree mortality. Science advances, 9(39), eadh4973.
- Hamilton, M.M., Derkey, R.E., and Stradling, D.F., 2004, Geologic map of the Spokane Southwest 7.5-minute quadrangle, Spokane County, Washington, Washington Division of Geology and Earth Resources, Open File Report 2004-4.
- Hatem, A. E., Collett, C. M., Briggs, R. W., Gold, R. D., Angster, S. J., Field, E. H., & Powers, P. M. (2022). Simplifying complex fault data for systems-level analysis: Earthquake geology inputs for US NSHM 2023. Scientific data, 9(1), 506.
- Nelson, A. R., Personius, S. F., Sherrod, B. L., Kelsey, H. M., Johnson, S. Y., Bradley, L. A., & Wells, R. E. (2014). Diverse rupture modes for surface-deforming upper plate earthquakes in the southern Puget Lowland of Washington State. Geosphere, 10(4), 769-796.
- Pagani, M., Monelli, D., Weatherill, G., Danciu, L., Crowley, H., Silva, V., Henshaw, P., Butler, L., Nastasi, M., Panzeri, L. and Simionato, M. (2014). OpenQuake engine: An open hazard (and risk) software for the global earthquake model. Seismological Research Letters, 85(3), pp.692-702.
- Pratt, T. L., Troost, K. G., Odum, J. K., & Stephenson, W. J. (2015). Kinematics of shallow backthrusts in the Seattle fault zone, Washington State. Geosphere, 11(6), 1948-1974.
- Styron, R. H., & Sherrod, B. (2021). Improving paleoseismic earthquake magnitude estimates with rupture length information: application to the Puget Lowland, Washington State, USA. Bulletin of the Seismological Society of America, 111(2), 1139-1153.
- Waite, G. P., & Moran, S. C. (2009). VP Structure of Mount St. Helens, Washington, USA, imaged with local earthquake tomography. Journal of Volcanology and Geothermal Research, 182(1-2), 113-122.
- Wesnousky, S. G. (2008). Displacement and geometrical characteristics of earthquake surface ruptures: Issues and implications for seismic-hazard analysis and the process of earthquake rupture. Bulletin of the Seismological Society of America, 98(4), 1609-1632.
- Wicks, C., Weaver, C., Bodin, P., & Sherrod, B. (2013). InSAR Evidence for an active shallow thrust fault beneath the city of Spokane Washington, USA. Journal of Geophysical Research: Solid Earth, 118(3), 1268-1276.
- Worden, C.B., E. M. Thompson, M. Hearne, and D.J. Wald (2020). ShakeMap Manual Online: technical manual, user's guide, and software guide, U. S. Geological Survey. https://ghsc.code-pages.usgs.gov/esi/shakemap/. DOI: https://doi.org/10.5066/F7D21VPQ .