Anthony Lomax @ALomax@qoto.org
#Earthquake happenings+tidbits, maps, #MachineLearning... I'm ALomax Scientific: earthquake monitoring and analysis.
"seismicity is only the edges and shadows of complex, 3D space-time tectonic processes"
Car free for daily life since 1976.
Joined Nov 2022
We use NLL-SSST-coherence (https://doi.org/10.1029/2021JB023190) an enhanced, absolute-timing earthquake location procedure which uses 1) spatially-varying station time corrections to improve multi-scale precision and 2) waveform similarity to improve fine-scale precision.
Multi-scale smooth, planar or arcuate faults slip without geometric impediment, which likely influences earthquake initiation, rupture, rupture direction, and arrest. Extensive, smooth fault segments may even be necessary for large earthquake to occur.
@weareseismica While we image the Parkfield segment of the San Andreas Fault as a planar surface at seismogenic depth, we find the Central/Southern Calaveras fault is an arcuate surface which follows closely the circumference of a circle.
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
Large earthqueke Turkey, Syria
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
Large Earthquake
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
Climate Crisis
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
#Earthquake happenings+tidbits, maps, #MachineLearning... I'm ALomax Scientific: earthquake monitoring and analysis.
"seismicity is only the edges and shadows of complex, 3D space-time tectonic processes"
Car free for daily life since 1976.
Joined Nov 2022
