Anthony Lomax @ALomax@qoto.org

Now out in @weareseismica, our paper "Major California faults are smooth across multiple scales at seismogenic depth" https://seismica.library.mcgill.ca/article/view/324
Our relocated seismicity images faults at seismogenic depth as smooth, planar or arcuate surfaces across the sub-km to 10’s of km scales.

Map views of the relocated seismicity 2000-present with NCSS 2013 Mw5.7 fault plane (violet) from https://earthquake.usgs.gov/earthquakes/eventpage/nc71996906/moment-tensor
NCSS 2023 Mw5.5 fault plane (yellow) from https://earthquake.usgs.gov/earthquakes/eventpage/nc73886731/moment-tensor

Quick seismo-tectonic interpretation of high-precision relocations of the Mw5.5 2023-05-11 Lake Almanor, CA earthquake sequence and background seismicity since 2000: Normal-faulting 2023 mainshock rupture towards the NW; oblique, normal + strike-slip splay and 2013 faulting to the SE.

The NCSS 2013 Mw5.7 fault plane matches the tabular spread of most 2013 aftershocks (violet). The Mw5.7 event has oblique, right-lateral + extensional faulting.

The relocated seismicity and fault planes show non-coplanar but adjoining 2013 and 2023 faulting.

Apr 18, 1906 San Francisco earthquake: Sparse timing data (including quick reading of wall clocks by local observers!) are sufficient to estimate the hypocenter location within about 10-20km (red cloud) - the epicenter is quite near San Francisco. https://pubs.geoscienceworld.org/ssa/bssa/article/95/3/861/103179/A-Reanalysis-of-the-Hypocentral-Location-and

Apr 18, 1906 San Francisco earthquake: my work on the likely hypocenter location & complex ruptures in the focal region https://pubs.geoscienceworld.org/ssa/bssa/article/98/2/846/350139/Location-of-the-Focus-and-Tectonics-of-the-Focal

The 1906 M7.8 California earthquake occurred 117 years ago: 1906-04-18 13h12mUTC. Here is recent seismicity (1984-2022) west of San Francisco. The 1906 hypocenter was likely in the yellow box, perhaps within the deep, linear trend of recent earthquakes (yellow).

Precise, NLL-SSST-coherence earthquake relocations for the 2023 Mw7.8 and Mw7.6, Kahramanmaraş-Gaziantep, Turkey earthquake sequence (including 2020 Mw 6.8 Elazığ, Turkey sequence). Seismic arrival data from https://afad.gov.tr. Details & catalog available at: https://doi.org/10.5281/zenodo.7699881

M7.8 #earthquake #Turkey #Syria
The distance between the two blue markers in this map is ~330km. Some events to the SW could be on separate faults, events further to the NE may be triggered (???) or around the end of a (very long) main rupture (???). http://udim.koeri.boun.edu.tr/zeqmap/hgmmapen.asp

M 7.8 #earthquake SE Turkey
https://earthquake.usgs.gov/earthquakes/eventpage/us6000jllz/executive

And the corresponding map view.

High-precision relocations of M≥2 1982 to 2021/12 done with NLL-SSST-coherence (https://doi.org/10.1029/2021JB023190), past year done with NLL-SSST.

Earthquake arrival data from service.ncedc.org/fdsnws

UPDATED: 2022-12-20 M6.4 #earthquake near Ferndale, CA: Seismicity since M6.4 (red), the past year (cyan) and back to 1982 (blue-purple). 2022-12-20 M6.4 events may be in upper part of down-going, Gorda plate or in lower part of over-riding North American plate.

And, since seismicity is only the edges and shadows of complex, 3D space-time tectonic processes, the best is an animated view in 3D!

M6.4 #earthquake near Ferndale, CA: Seismicity for today (red), the past year (orange) and back to 1982 (green-blue-purple). Views from above/south/east. Today's events may be in upper part of down-going, Gorda plate.

Unusual location for a moderate size #earthquake:
M5.7 Gabon 2022.12.04-09:53UTC
http://alomax.free.fr/projects/early-est//events/hypo.1670147597541.map.html

Mwp6.1 #earthquake Baja California, Mexico 2022.11.22-16:39UTC http://early-est.alomax.net
Somewhat unusual location for an M6 earthquake, clearly to the southwest of the main San Andreas and Gulf of California plate boundary faults.

Location and First-motion mechanism: Mwp6.8 #earthquake Southwest of Sumatra, Indonesia http://early-est.alomax.net http://alomax.free.fr/projects/early-est/events/hypo.1668778608226.html

5°C above average today (SE France). Seems it has generally been 3-5°C above average this year. This is fine?
#ClimateCrisis #Climate
https://meteofrance.com/changement-climatique