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#seismichazard

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💧🌏 Greg Cocks

The 2023 US 50-State National Seismic Hazard Model - Overview And Implications
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usgs.gov/programs/earthquake-h <-- USGS technical article
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doi.org/10.1177/87552930231215 <-- shared paper
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@USGS @FEMA

A map from the 2018 United States Seismic Hazard Model showing highest hazard in red and lowest hazard in gray. Damage from various earthquakes around the U.S. is shown in the photographs. Larger versions of each photo can be found at: 2001 M6.8 Nisqually, Washington, 2014 M6.0 South Napa, California, 1994 M6.7 Northridge, California, 1975 M7.7 Kalapani, Hawaii, 2011 M5.8 Mineral, Virginia, and 2018 M7.1 Anchorage, Alaska.
maps - The 2023 Modified Mercalli Intensity (MMI) hazard maps of the conterminous United States showing estimates of earthquake shaking in terms of (1) 50% probability of exceedance (PE) in 50 years (somewhat likely), (b) 10% PE in 50 years (uncommon), and (c) 2% PE in 50 years (rare).
maps - Maps show faults, zones applied in the CEUS, and zones of ground-motion model (GMM) amplification for the 2023 50-State National Seismic Hazard Model. The inset map is a close-up view of the New Madrid seismic zone area (orange dashed boundary). Spatial boundaries include potentially induced earthquakes for the update and the previous 2018 zones, 2023 central and eastern United States (CEUS)–western United States (WUS) attenuation boundary update and 2018 boundary, WUS basins, and two areas of uniform seismicity. Fault sections for the WUS (Hatem et al., 2022a, 2022b) and for Alaska from Bender et al. (2021) are shown colored according to slip rates. Fault sections in the CEUS are not shown according to slip rates but all slip rates are less than 0.2 mm/year. The Alaska megathrust is represented by 14 segmented zones. Damaging earthquake locations are shown in all three maps. In addition, we show seismicity for Alaska (M7+) and Hawaii (M5+) (Petersen et al., 2021; Rukstales et al., 2021)....
maps and charts - Normalized probability density function grids of seismicity-based earthquake rates (no fault models) are displayed for (a) the western United States (WUS), (b) the central and eastern United States (CEUS), (c) Alaska, and (d) Hawaii...
Public
💧🌏 Greg Cocks

Deep Structure of Siletzia in the Puget Lowland - Imaging an Obducted Plateau and Accretionary Thrust Belt With Potential Fields
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doi.org/10.1029/2022TC007720 <--shared paper
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[I used to live, work as an engineering geologist and scuba dive in Puget Sound & beyond – including on the expressions of the Seattle Fault…]

imagery / photos - aerial - remotesensing sensing - LiDAR - the expression of the Seattle Fault on southern Bainbridge Island
map and model - Fold and thrust belt interpretation superimposed on the aeromagnetic map shown in Figure 4. Interpreted reverse faults bear hachures. Unadorned, solid lines show the positions of other boundaries, many of which we interpret as the boundary between the upper and lower Crescent Formations, especially where they are positioned parallel to and between two reverse faults. All lines closely follow linear maximum gradients identified from the pseudogravity map (Figure 5), however, dotted lines indicate linear features that are less certain. Solid boundaries and reverse faults in the Olympic Mountains (bordering the area marked as mapped upper and lower Crescent Formations) also have geologic mapping support. Labels identify major tectonic elements corresponding to the text and the light brown lines indicate the positions of the geophysical models in Figures 8-10. KA, Kingston arch; SFZ (gray area), Seattle fault zone; SU, Seattle uplift.
graphic / map - hillshade and annotations showing the Seattle Fault Zone, Puget Sound
map and model - Contoured isostatic residual gravity in milligals (mGal) for the Puget Lowland. Contour interval is 5 mGal, and small crosses show location of data points constraining the gravity grid. The bold contour highlights the potential shape of the Seattle basin as discussed in the text. Blue-outlined transparent polygons are waterways. Brown lines show locations of models in Figures 8-10 (A–A′, B–B′, and C–C′, respectively). Thick, gray lines (labeled 1, 2, and 3) show potential locations of the Siletzia eastern boundary from pseudogravity gradient analysis shown in Figure 5 and discussed in the text; the solid line (3) indicates the most likely position. EB, Everett basin; EO, small Eocene basin; HC, Hood Canal; KA, Kingston arch; M, Monroe; MB, Muckleshoot basin; NB, North Bend; OS, metasediments of the Olympic accretionary core; PP, Pulali Point; PS, Puget Sound; RF, Rattlesnake Mountain fault zone; S, Seattle; SB, Seattle basin; SFG, Seattle fault gravity gradient; SU, Seattle uplift; SWIF, Southern Whidbey Island fault; TB, Tacoma basin.
Public
Doug Bostrom

"The potency of earthquakes in each country, we define as the sum of fatalities reported divided by the number of earthquakes that generated the associated disasters. Thus, the potency measures the size of the disaster generated by an average fatal earthquake in each country."

Unexpected?

"The leaders in the list of potency are Haiti, Azerbaijan, Syria and Israel, all with potencies above 20,000 fatalities per average earthquake."

#SeismicHazard
#OpenAccess
link.springer.com/article/10.1

SpringerLinkEarthquake fatalities and potency - Natural HazardsWe have compiled a new catalogue of earthquake fatalities for the world, covering the period 856 BC to March 2022, listing 2795 reports. We estimate that the reporting of fatal earthquakes is complete for events with more than 16 fatalities since 1927. The total number of fatalities recorded is 8,336,526. 117 countries have reported at least one earthquake with one fatality or more. 77 and 52 countries have reported more than 100 and 1000 earthquake fatalities, respectively. Caution has to be exercised in estimating what earthquake disasters are in store for a given country because the 95 year period of high quality recording is about an order of magnitude shorter than return times of great earthquakes. Nevertheless, we introduce the earthquake potency for a country, defined as the sum of recorded fatalities divided by the number of earthquakes that it took to accumulate them, which equals the average earthquake disaster size in a given country, in units of fatalities per event. Potency is listed based on all known fatal earthquakes and also based on those since 1927. Both lists have their shortcomings, but provide estimates of what size of future earthquake disaster is likely in store for a particular country. For rescue purposes, it is important to realize that small earthquake, M 5 ± 0.5, can cause significant numbers of fatalities.
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Dr. Tiegan Hobbs

Hi! I’m a research scientist at the Geological Survey of Canada and adjunct professor at the University of British Columbia and the University of Victoria. I study #earthquakes and focus mostly on #SeismicRisk and #ActiveTectonics. I’m interested in #Paleoseismology #Neotectonics #Seismology #Geodesy and #SeismicHazard.

I’m also chair of the #AGU Hazards Equity Working Group, a Fast Reports editor at @weareseismica and a Building Equity & Capacity committee member for #SZ4D.

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