Shear-Wave Velocity Structure in Southeast Asia from the 2025 Mw 8.8 Kamchatka Earthquake Using Hilbert–Huang Transform

Kurniawan, Andri; Dani, Ilham; Erfani, Sandri

doi:10.70561/geocelebes.v9i2.47278

Open access Jurnal

Shear-Wave Velocity Structure in Southeast Asia from the 2025 Mw 8.8 Kamchatka Earthquake Using Hilbert–Huang Transform

JURNAL GEOCELEBES · Vol. 9 No. 2 (2025) · pp. 213–225

DOI: 10.70561/geocelebes.v9i2.47278
ISSN: 2579-5546, 2579-5821
Published: 2025-10-30
Publisher: Departemen Geofisika, FMIPA - Universitas Hasanuddin, Makassar
Language: en
License: creativecommons.org/licenses/by-nc-sa/4.0

Abstract

The 2025 Mw 8.8 Kamchatka earthquake generated long-period teleseismic surface waves recorded at stations in Australia (CTAO), Thailand (CHTO), and Indonesia (KAPI) at epicentral distances of ~6,400–8,200 km. These records provide a useful dataset to probe crust and upper-mantle structure across contrasting Southeast Asian tectonic domains. We apply the Hilbert–Huang Transform (HHT) to vertical seismograms to extract dispersion from non-stationary wave trains. Seismograms are decomposed by empirical mode decomposition, and dispersion ridges in the Hilbert spectrum are tracked to identify frequency-dependent group arrivals. Group-velocity curves are smoothed with a low-order polynomial, and dual-frequency anchors are used to enforce phase-velocity continuity. Group velocities increase from ~3.0 km/s at periods ≥150 s to ~5.5 km/s at 40–60 s, while phase velocities span 3.3–4.6 km/s. Phase-velocity curves initialized with CRUST1.0 are inverted for 1-D shear-wave velocity (Vs), indicating crustal thicknesses of ~30–40 km: thicker beneath CHTO, intermediate at CTAO, and thinner with a slower upper mantle beneath KAPI. These lithospheric variations are consistent with regional deformation inferred from GPS and InSAR. Overall, HHT yields stable dispersion measurements and reliable Vs models relative to global references, underscoring its utility in complex tectonic regions.

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Co-author	Organisation	Joint articles
Nailatussa'adah	Affiliation unknown	2
Rosna Amaliaatul Ma’rifah	Affiliation unknown	2
M. Rayya Andisa Putra	Affiliation unknown	2
Eka Andika	Affiliation unknown	2
Ahmad Zaenudin	Affiliation unknown	1
Niar Amalia	Affiliation unknown	1
Syamsurijal Rasimeng	Affiliation unknown	1
Ambrosius Hernawan Wibisono	Affiliation unknown	1
Restu Wildanu Ahadi	Affiliation unknown	1
Sultan Al Ghifari	Affiliation unknown	1
Anisa Amanda	Affiliation unknown	1
Rizki Buana Agustian	Affiliation unknown	1
Aksela Dian Fista	Affiliation unknown	1

Affiliations come from OpenAlex; journal OAI-PMH metadata carries none. Authors without an OpenAlex ID are matched by name, which can merge or split people.

Metadata source: OAI-PMH (metadata jurnal) https://journal.unhas.ac.id/index.php/geocelebes/oai, first harvested 3 Nov 2026, last seen 3 Nov 2026.

Original metadata (oai_dc)

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	<dc:title xml:lang="en">Shear-Wave Velocity Structure in Southeast Asia from the 2025 Mw 8.8 Kamchatka Earthquake Using Hilbert–Huang Transform</dc:title>
	<dc:creator xml:lang="en">Kurniawan, Andri</dc:creator>
	<dc:creator xml:lang="en">Dani, Ilham</dc:creator>
	<dc:creator xml:lang="en">Erfani, Sandri</dc:creator>
	<dc:subject xml:lang="en">crustal thickness</dc:subject>
	<dc:subject xml:lang="en">dispersion analysis</dc:subject>
	<dc:subject xml:lang="en">Hilbert–Huang Transform</dc:subject>
	<dc:subject xml:lang="en">Rayleigh waves</dc:subject>
	<dc:subject xml:lang="en">shear-wave velocity</dc:subject>
	<dc:subject xml:lang="en">Southeast Asia</dc:subject>
	<dc:description xml:lang="en">The 2025 Mw 8.8 Kamchatka earthquake generated long-period teleseismic surface waves recorded at stations in Australia (CTAO), Thailand (CHTO), and Indonesia (KAPI) at epicentral distances of ~6,400–8,200 km. These records provide a useful dataset to probe crust and upper-mantle structure across contrasting Southeast Asian tectonic domains. We apply the Hilbert–Huang Transform (HHT) to vertical seismograms to extract dispersion from non-stationary wave trains. Seismograms are decomposed by empirical mode decomposition, and dispersion ridges in the Hilbert spectrum are tracked to identify frequency-dependent group arrivals. Group-velocity curves are smoothed with a low-order polynomial, and dual-frequency anchors are used to enforce phase-velocity continuity. Group velocities increase from ~3.0 km/s at periods ≥150 s to ~5.5 km/s at 40–60 s, while phase velocities span 3.3–4.6 km/s. Phase-velocity curves initialized with CRUST1.0 are inverted for 1-D shear-wave velocity (Vs), indicating crustal thicknesses of ~30–40 km: thicker beneath CHTO, intermediate at CTAO, and thinner with a slower upper mantle beneath KAPI. These lithospheric variations are consistent with regional deformation inferred from GPS and InSAR. Overall, HHT yields stable dispersion measurements and reliable Vs models relative to global references, underscoring its utility in complex tectonic regions.</dc:description>
	<dc:publisher xml:lang="en">Departemen Geofisika, FMIPA - Universitas Hasanuddin, Makassar</dc:publisher>
	<dc:date>2025-10-30</dc:date>
	<dc:type>info:eu-repo/semantics/article</dc:type>
	<dc:type>info:eu-repo/semantics/publishedVersion</dc:type>
	<dc:type xml:lang="en">Peer-reviewed Article</dc:type>
	<dc:format>application/pdf</dc:format>
	<dc:identifier>https://journal.unhas.ac.id/index.php/geocelebes/article/view/47278</dc:identifier>
	<dc:identifier>10.70561/geocelebes.v9i2.47278</dc:identifier>
	<dc:source xml:lang="en">JURNAL GEOCELEBES; Vol. 9 No. 2: October 2025; 213–225</dc:source>
	<dc:source>2579-5546</dc:source>
	<dc:source>2579-5821</dc:source>
	<dc:language>en</dc:language>
	<dc:relation>https://journal.unhas.ac.id/index.php/geocelebes/article/view/47278/13674</dc:relation>
	<dc:rights xml:lang="en">Copyright (c) 2025 JURNAL GEOCELEBES</dc:rights>
	<dc:rights xml:lang="en">https://creativecommons.org/licenses/by-nc-sa/4.0</dc:rights>
</oai_dc:dc>