[IGSSTATION-8930] Additional information about the Myanmar earthquake
Freymueller, Jeffrey
freymuel at msu.edu
Thu Apr 3 15:10:00 UTC 2025
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An addendum to IGSSTATION-8929.
The latest information (from satellite image cross-correlation) shows that the rupture length for this earthquake was about 500 km, which is exceptionally long for an event of this magnitude, and this length is well outside of the usual scaling relationships. It is a remarkably long rupture, in fact, and one of the longest single fault strike-slip rupture ever, perhaps even the longest yet observed that did not involve multiple distinct faults. This also means that the width (in depth) of the rupture was probably lower than normal in the scaling relationships as well. And as a result, prediction error is likely to be larger than usual – although because all of the IGS sites are quite distant the displacements will likely be small, as predicted by the IGS-RF calculation.
But if you see a larger-then-normal difference between the IGS-RF prediction and what you observe, it is a consequence of the unusual nature of the earthquake.
The most recent version of the USGS finite fault model (version 3) includes information from one satellite image correlation data set, but not yet the SAR image correlation or InSAR (data covering part of the fault are now available as of yesterday). I expect that the USGS will continue to update and the model will become more accurate.
https://earthquake.usgs.gov/earthquakes/eventpage/us7000pn9s/finite-fault
If you scroll down to the Downloads section on that page and expand it, you can find a file with predicted displacements on a grid, but the grid does not cover much more than Myanmar so I think CMUM is the only IGS site included. They also provide an input file for the Coulomb software, which can be used to compute displacements at any point you want, although with an elastic half-space approximation.
Jeff
--------------
Dr. Jeffrey T. Freymueller
Endowed Chair for Geology of the Solid Earth
Department Chair
Dept. of Earth and Environmental Sciences
Michigan State University
URL: https://msu.edu/~freymuel/
From: IGSSTATION <igsstation-bounces at lists.igs.org> on behalf of igs-rf at ign.fr <igs-rf at ign.fr>
Date: Thursday, April 3, 2025 at 8:58 AM
To: igsstation at lists.igs.org <igsstation at lists.igs.org>
Subject: [IGSSTATION-8929] Possible co-seismic displacements: BNEU, CMUM, CUSV, CUUT, LHAZ, NIUM, NKAY, PBR4, SHLG, TOAY, TONG
# Author : Paul Rebischung
# Contact : igs-rf at ign.fr
# Subject : Possible co-seismic displacements: BNEU, CMUM, CUSV, CUUT, LHAZ, NIUM, NKAY, PBR4, SHLG, TOAY, TONG
#
# This is a notification that recent earthquake(s) may have induced noticeable displacements of one or more IGS stations.
#
# This message and the table below were generated automatically based on the following procedure:
# * The Global Centroid-Moment-Tensor (CMT) catalog (https://urldefense.com/v3/__https://www.globalcmt.org/__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h-KD0jbug$ ) is scanned every day for new earthquakes.
# * For every new earthquake, the width, length and slip of the rupture are estimated from:
# - Yen & Ma (2012; https://urldefense.com/v3/__https://doi.org/10.1785/0120100046)'s__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h-5NJT0GQ$<https://urldefense.com/v3/__https:/doi.org/10.1785/0120100046)'s__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h-5NJT0GQ$> scaling law if the earthquake magnitude is less than 7.6;
# - Mai & Beroza (2000; https://urldefense.com/v3/__https://doi.org/10.1785/0119990126)'s__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h_fbt1WlQ$<https://urldefense.com/v3/__https:/doi.org/10.1785/0119990126)'s__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h_fbt1WlQ$> scaling law it the earthquake magnitude is larger.
# (See justification for these choices in Métivier et al., 2014; https://urldefense.com/v3/__https://doi.org/10.1002/2014JB011280__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h9cNea-JQ$<https://urldefense.com/v3/__https:/doi.org/10.1002/2014JB011280__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h9cNea-JQ$> .)
# * For every new earthquake, based on its estimated CMT and rupture parameters, co-seismic displacements are calculated
# at all IGS stations using Okada (1985; https://urldefense.com/v3/__https://doi.org/10.1785/BSSA0750041135)'s__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h8ZX_nGCA$<https://urldefense.com/v3/__https:/doi.org/10.1785/BSSA0750041135)'s__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h8ZX_nGCA$> approach. Given that the CMT inversion
# from seismic waves gives rise to two possible solutions for the rupture plane, two possible co-seismic displacements
# are calculated for every station and earthquake.
# * If any calculated 3D co-seismic displacement of an IGS station exceeds 1 mm, it is included in the table below.
#
# Warning : The co-seismic displacements thus calculated rely on several coarse approximations. They should not be used as
# estimates of the actual co-seismic displacements, but only as rough orders of magnitude.
#
# The column "RF?" in the table below indicates whether each station is part of the current IGS reference frame (IGb20),
# hence might need to stop being used as a reference frame station after the earthquake.
#
# The successive co-seismic displacements thus calculated are compiled in a cumulative table available at:
# https://urldefense.com/v3/__ftp://igs-rf.ign.fr/pub/coseismic/IGS_coseismic.dat__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h8qCkbrfA$<https://urldefense.com/v3/__ftp:/igs-rf.ign.fr/pub/coseismic/IGS_coseismic.dat__;!!HXCxUKc!0jZXX41TyTmxA0_4_0HEhRfU4A52P7_rgixqmBMYj6mDWdfTHmMZc0ryyKdxshcvrqby3h8qCkbrfA$>
#
#__________station_________ ___________________________earthquake_____________________________ dist_ _____displacement1_____ _____displacement2_____
#sta_ lon[deg] lat[deg] RF? date_______________ Mw_ location________________ lon[deg] lat[deg] d[km] dE[mm]_ dN[mm]_ dH[mm]_ dE[mm]_ dN[mm]_ dH[mm]_
#-----------------------------------------------------------------------------------------------------------------------------------------------------------
BNEU 101.917 21.644 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 620 1.3 -1.9 -0.6 1.4 -1.9 -0.6
CMUM 98.932 18.761 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 479 6.0 -5.2 -2.8 5.9 -5.1 -2.8
CUSV 100.534 13.736 Yes 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 1041 1.0 -0.8 -0.5 1.0 -0.8 -0.5
CUUT 100.534 13.736 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 1041 1.0 -0.8 -0.5 1.0 -0.8 -0.5
LHAZ 91.104 29.657 Yes 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 977 -1.1 0.9 -0.6 -1.1 0.9 -0.6
NKAY 105.153 17.719 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 1077 1.2 -0.9 -0.6 1.2 -0.9 -0.6
PBR4 92.712 11.637 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 1203 0.6 0.8 0.3 0.6 0.8 0.4
SHLG 91.913 25.674 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 576 -4.0 3.4 -2.1 -4.0 3.4 -2.0
TOAY 106.627 16.073 No 2025-03-28 06:20:54 7.7 Myanmar 95.920 22.010 1304 0.8 -0.7 -0.4 0.9 -0.7 -0.4
NIUM -169.927 -19.077 Yes 2025-03-30 12:18:46 7.0 Tonga Islands -174.110 -20.500 465 -1.1 -0.4 0.2 -1.1 -0.4 0.2
TONG -175.179 -21.145 No 2025-03-30 12:18:46 7.0 Tonga Islands -174.110 -20.500 132 12.9 7.4 1.0 12.7 7.0 1.7
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