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S-wave modelling of the Showa-Shinzan lava dome in Usu Volcano, Northern Japan, from seismic observations.
- Source :
-
Geophysical Journal International . Sep2022, Vol. 230 Issue 3, p1662-1678. 17p. - Publication Year :
- 2022
-
Abstract
- To obtain an internal S -wave velocity structure, we conducted a passive seismic campaign with 21 1-Hz seismometers on and around the Showa-Shinzan lava dome, which emerged during the 1943–1945 eruption of Usu Volcano, Japan. Before the campaign, we calibrated seismometers and found slight phase-response differences between seismometers of less than 1–2°. After the campaign, we extracted seismic wavefield by taking cross-correlations of vertical-component ambient noise records between seismic sites. We developed a new method to measure phase velocities of the Rayleigh wave automatically by assuming layered structure and finally obtained 1-D S -wave velocity models in summit, roof and base regions. The obtained S -wave velocity right beneath the intruded lava dome is higher than that in surrounding areas by a few tens of per cent down to a few hundred metres below sea level, indicating narrow but deep existence of the root of the lava dome. The obtained S -wave velocity at depths shallower than ∼50 m inside the lava dome in the summit area was ∼1 km s−1, significantly lower than that predicted from the density of  2.3 × 103 kg m−3 estimated in previous muon-radiography studies and a conventional scaling, indicating the effect of cracking in the lava dome. [ABSTRACT FROM AUTHOR]
- Subjects :
- *LAVA domes
*SHEAR waves
*VOLCANOES
*RAYLEIGH waves
*PHASE velocity
Subjects
Details
- Language :
- English
- ISSN :
- 0956540X
- Volume :
- 230
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Geophysical Journal International
- Publication Type :
- Academic Journal
- Accession number :
- 158364611
- Full Text :
- https://doi.org/10.1093/gji/ggac111