specfem

vertical displacement of station AB.HASN

vertical displacement of station AB.YNKD

vertical displacement of station IU.GNI

air strike reported on June 22, 2025, 2:30am local time (23:00 UTC on 2025-06-21) - not much visible in available data at closest stations AB.HASN, AB.YNKD and IU.GNI (~500-800 km away from Fordow site). main signal visible between 21:45-22:15 UTC is a Mw6.0 earthquake (epicenter in Japan)

#specfem3d peak-ground motion (PGV) shakemap of the time-reversal simulation of the Birch glacier collapse. it should highlight the event site - but sometimes things are not so simple.

#specfem3d time-reversal simulation of the Birch glacier collapse. Reinjecting seismic data from all available Swiss broadband stations together with the velocity model from Diehl et al. (2021) pinpoints the source of all that seismic energy...

YouTube video by ChEESE CoE SPECFEM Code: Advancing Seismic Wave Simulation

New ChEESE Codes Interview: SPECFEM!

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Spectral accelerations (SA) at the Bangkok building collapse site based on the synthetics of the updated USGS finite-fault solution of the Myanmar Mw7.7 earthquake #specfem3d #USGS

#shakemovie simulation with the updated USGS finite-fault solution of the Myanmar Mw7.7 #earthquake w/ USGS Vs30 and EarthScope EMC FWEA23 (Liu et al. 2024) model #specfem3d #USGS #EarthScope #blender

PGV shakemap for the Myanmar Mw7.7 earthquake using the updated version of the USGS finite-fault solution

PGV shakemap for the Myanmar Mw7.7 #earthquake based on the updated version of the USGS finite-fault solution #specfem3d #shakemap #USGS

PGV shakemap for the Myanmar Mw7.7 earthquake

PGV shakemap for the Myanmar Mw7.7 #earthquake based on USGS finite-fault solution #specfem3d #shakemap

2025-03-28 Myanmar Mw7.7 #earthquake - shakemovie simulation w/ USGS finite-fault solution and IRIS EMC GLAD-M35 (Cui et al. 2024) model #specfem3d #shakemovie #geoscience #USGS #EarthScope #blender #b3d

Last Friday, two strong Mw6.2 earthquakes struck near Panama and Alaska - just ~3 minutes apart - followed by a smaller Mw5.7 quake. As if Panama and Alaska decided to sync up.. here’s a #shakeMovie visualization - watch as they light up the Earth with some nice fringes #specfem3dGLOBE

screenshot of google scholar page of SPECFEM hitting 30k+ citations

#SPECFEM codes hit 30,000+ citations!

awkward moment. when your simulation software has a bigger social circle than you do and your code is more popular than you’ll ever be. 🙂 well done Dimitri.

specfem.org

:) right, that’s really more due to the choice of using an integer to represent your date rather than a Fortran limit. the same would’ve happened using other programming languages such as C/C++, C#, Java, .. as they all use mostly 32-bit integers by default these days.

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The global CMT project 2004–2010: Centroid-moment tensors for 13,017 earthquakes Earthquake moment tensors reflecting seven years of global seismic activity (2004–2010) are presented. The results are the product of the global centr…

sure, happy to provide more details 🙂

the differences here with the wavefronts are due to differences in the earthquake source description, i.e., between a single centroid (CMT) source www.sciencedirect.com/science/arti...

vs. a finite-fault description earthquake.usgs.gov/data/finitef...

for comparison, this simulation is using the same mesh resolution, but with flat topography and just a single centroid-moment tensor (CMT) source. the noisy scattering pattern is mostly due to the USGS finite-fault solution that uses 147 single point sources with interfering wavefields.

might be - this is still a very simplistic model and the finite-element mesh is rather coarse. the spectral-element method however doesn't necessarily need further smoothing.

I guess part of the grid structure you notice is also just due to the visualization...

:) not all of it are artifacts - the main numerical noise are the small reflections of the absorbing boundaries, mostly visible after the strong surface waves hit the box walls. the overalll small-scale scattering you see is not artifacts, but scattering due to the strong topography in this region.

Peak-Ground Velocity (PGV) shakemap for the Shigatse Mw 7.1 earthquake.

PGV shakemap for the Shigatse Mw 7.1 #earthquake based on USGS finite-fault solution #specfem3d #shakemap

2025-01-07 Shigatse Mw 7.1 #earthquake - shakemovie simulation w/ USGS finite-fault solution and IRIS EMC GLAD-M35 (Cui et al. 2024) model #specfem3d #shakemovie #geoscience #USGS #IRIS #EarthScope #blender #b3d

PGV shakemap using USGS VS30 near-surface model in local simulation for the city of Freiburg, Germany, of the Waldkirch 2004 Mw4.7 event

PGV shakemap without VS30 near-surface model of the Waldkirch 2004 Mw4.7 event

Peak-Ground Velocity (PGV) maps do care about small-scale effects - here's using the local simulation with and without the USGS VS30 near-surface velocity model (background regional model from IRIS EMC LSP_Eucrust1.0, Lu et al. 2018)

#specfem3d example of computing the shaking of the 2004 Dec. 5 Waldkirch event (~Mw4.7) in the nearby city of Freiburg, Germany, by injecting the regional wavefield into a very small-scale local simulation (grid point spacing ~15m) - wavefield injection from regional into local SPECFEM3D

interesting, thanks for checking it out!

hi Jay, is there any data/information about land subsidence or sea level rise at the coasts of Efate island or in particular at Port Vila?

my simulations with the USGS finite-fault solutions show a 10cm subsidence at Port Vila… that’s quite a sea level rise over night.

Peak Ground Velocity (PGV) shakemap for the Vanuatu Mw 7.3 earthquake

PGV shakemap for the Vanuatu Mw 7.3 #earthquake based on USGS finite-fault solution #specfem3d #shakemap

2024-12-17 Vanuatu Mw 7.3 #earthquake - shakemovie simulation w/ USGS finite-fault solution and IRIS EMC GLAD-M35 (Cui et al. 2024) model #specfem3d #science #USGS #IRIS #blender #b3d

nice to see that Ebru and Dave’s Earth model visualization made an impression 🙂 #specfem3d_globe

here’s a visualization of seismic waves generated by this finite-fault solution bsky.app/profile/spec...

PGV shakemap for the 2024-04-02 Taiwan Mw 7.4 earthquake

PGV shakemap for the 2024-04-02P Hualien City, Taiwan Mw 7.4 earthquake based on USGS finite-fault solution #specfem3d #earthquake #shakemap