Seismic analysis and distribution of a bottom-simulating reflector (BSR) in the Chilean margin offshore of Valdivia (40° S)

Cristián Rodrigo, Emilio Vera, Antonio González-Fernández

Resultado de la investigación: Article

9 Citas (Scopus)

Resumen

Multi-channel seismic (MCS) reflection data recorded offshore from Valdivia (40° S), in the Chilean margin, were processed to obtain a seismic image to establish structural characteristics and relate them to the presence of the bottom-simulating reflector (BSR). Seismic structure velocity of the BSR was determined using 1-D forward modeling. Recorded seismograms for two representative common mid-point (CMP) gathers were compared with synthetics, using different physical parameters to fit the waveforms. Our results confirm the presence of gas hydrates above the BSR. The BSR spatial continuity appears to be either interrupted or irregular due to the presence of faults. Tectonic movements can change the gas hydrate stability zone and consequently the BSR disappears or becomes weaker. Structural and topographic factors, differences in concentration, vertical distribution characteristics and internal structure of gas hydrates can influence BSR amplitude behavior. Variability in the concentration, volume, and extra supply of free gas coming from faults could be the main factors in the change of BSR amplitudes. The inclusion of the attenuation factor in the modeling supports the existence of free gas below the BSR. It is possible that the free gas below the BSR is distributed in bubbles or "bags".

Idioma originalEnglish
Páginas (desde-hasta)1-10
Número de páginas10
PublicaciónJournal of South American Earth Sciences
Volumen27
N.º1
DOI
EstadoPublished - 1 feb 2009

Huella dactilar

gas hydrate
gas
forward modeling
seismogram
velocity structure
seismic reflection
bubble
vertical distribution
tectonics
modeling
distribution
analysis

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

Citar esto

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abstract = "Multi-channel seismic (MCS) reflection data recorded offshore from Valdivia (40° S), in the Chilean margin, were processed to obtain a seismic image to establish structural characteristics and relate them to the presence of the bottom-simulating reflector (BSR). Seismic structure velocity of the BSR was determined using 1-D forward modeling. Recorded seismograms for two representative common mid-point (CMP) gathers were compared with synthetics, using different physical parameters to fit the waveforms. Our results confirm the presence of gas hydrates above the BSR. The BSR spatial continuity appears to be either interrupted or irregular due to the presence of faults. Tectonic movements can change the gas hydrate stability zone and consequently the BSR disappears or becomes weaker. Structural and topographic factors, differences in concentration, vertical distribution characteristics and internal structure of gas hydrates can influence BSR amplitude behavior. Variability in the concentration, volume, and extra supply of free gas coming from faults could be the main factors in the change of BSR amplitudes. The inclusion of the attenuation factor in the modeling supports the existence of free gas below the BSR. It is possible that the free gas below the BSR is distributed in bubbles or {"}bags{"}.",
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Seismic analysis and distribution of a bottom-simulating reflector (BSR) in the Chilean margin offshore of Valdivia (40° S). / Rodrigo, Cristián; Vera, Emilio; González-Fernández, Antonio.

En: Journal of South American Earth Sciences, Vol. 27, N.º 1, 01.02.2009, p. 1-10.

Resultado de la investigación: Article

TY - JOUR

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AU - Vera, Emilio

AU - González-Fernández, Antonio

PY - 2009/2/1

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AB - Multi-channel seismic (MCS) reflection data recorded offshore from Valdivia (40° S), in the Chilean margin, were processed to obtain a seismic image to establish structural characteristics and relate them to the presence of the bottom-simulating reflector (BSR). Seismic structure velocity of the BSR was determined using 1-D forward modeling. Recorded seismograms for two representative common mid-point (CMP) gathers were compared with synthetics, using different physical parameters to fit the waveforms. Our results confirm the presence of gas hydrates above the BSR. The BSR spatial continuity appears to be either interrupted or irregular due to the presence of faults. Tectonic movements can change the gas hydrate stability zone and consequently the BSR disappears or becomes weaker. Structural and topographic factors, differences in concentration, vertical distribution characteristics and internal structure of gas hydrates can influence BSR amplitude behavior. Variability in the concentration, volume, and extra supply of free gas coming from faults could be the main factors in the change of BSR amplitudes. The inclusion of the attenuation factor in the modeling supports the existence of free gas below the BSR. It is possible that the free gas below the BSR is distributed in bubbles or "bags".

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