Attenuation and source parameters at Deception Island (South Shetland Islands, Antarctica)

Vilà, Joaquim; Correig, Antoni M.; Martı́, Joan

doi:10.1007/bf00878633

Cited by 23 publications

(26 citation statements)

References 21 publications

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“…1) and is characterized by a significant sesimic activity, mainly represented by small magnitude local events. Main general geophysical and seismic features of Deception Island have been deduced by ORTIZ et al (1992) and VILA et al (1992VILA et al ( , 1995. It is of interest for the present study that, averaged over a few days, the rate of energy release is constant, suggesting a stationary event occurrence.…”

Section: Introductionmentioning

confidence: 66%

“…In order to define a physical model compatible with these characteristics of the seismicity, it is also necessary to consider three main geophysical observations made in previous studies of Deception Island ORTIZ et al, 1992;VILA et al, 1995): 1) The energy flux is constant: there is a constant energy release and also a constant supply of energy from the magma sources and from the tectonic movements.…”

Section: Discussionmentioning

confidence: 99%

“…The general trends of the seismicity of Deception Island have been studied by VILA et al (1992VILA et al ( , 1995, and indicate that the rate of energy release, averaged over a few days, remains constant and is of the order of 3.0× 10 6 jouls/day. The Gutenberg-Richter distribution for local events reveals an average value b= 1.4 .…”

Section: General Features Of Deception Island and Selection Of Datamentioning

confidence: 99%

“…The Gutenberg-Richter distribution for local events reveals an average value b= 1.4 . In VILA et al (1995), an estimation of the attenuation and of source parameters was done. With respect to the attenuation, an abnormally high value was found; in terms of the intrinsic Q(f) fitted to a power law Q(f)= Q 0 f p , the following average values were obtained: Q 0 10 and p 1.3.…”

Section: General Features Of Deception Island and Selection Of Datamentioning

confidence: 99%

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Analysis of the Temporal Occurrence of Seismicity at Deception Island (Antarctica). A Nonlinear Approach

Correig

Urquizú

Vilà

et al. 1997

Pure and Applied Geophysics

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Deception Island is characterized by small magnitude local events with constant energy flux and very low stress drop. To obtain information about its origin, an interevent time series of 546 events, corresponding to an observational period of two month, has been analyzed. From a statistical point of view, data satisfies a Weibull distribution and presents clustering. A rescaled range analysis reveals that data are not independent, i.e. have memory, and the correlation dimension saturates at 2.2; as a consequence, the system can be modeled as a nonlinear iterative equation with three degrees of freedom that presents chaotic behavior. Taking into account that the average interevent time is of the order of 130 minutes, too short to be only due to tectonic activity, the above results indicate that some other mechanism may coexist with the regional tectonic one. According to several geological and geophysical observations, we suggest that most of the local events may be originated by pressure waves generated by a sudden change of phase, of sea and fresh water infiltrated into the main fractures and faults and also from shallow and confined water-saturated layers.

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Section: Introductionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: General Features Of Deception Island and Selection Of Datamentioning

confidence: 99%

Section: General Features Of Deception Island and Selection Of Datamentioning

confidence: 99%

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Analysis of the Temporal Occurrence of Seismicity at Deception Island (Antarctica). A Nonlinear Approach

Correig

Urquizú

Vilà

et al. 1997

Pure and Applied Geophysics

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“…It should be pointed out that the high-frequency observed in tremor seismograms may be detected only close to the source because of the high seismic attenuation of most volcanic areas (Q as low as 11, see e.g. Vila et al, 1995). Therefore, the source must be located very close to the array site.…”

Section: Introductionmentioning

confidence: 99%

Array tracking of the volcanic tremor source at Deception Island, Antarctica

Almendros¹,

Ibáñez²,

Alguacil³

et al. 1997

Geophysical Research Letters

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Abstract. We have found experimental evidence which shows that the volcanic tremor recorded at Deception Island (South Shetland Islands, Antarctica) is a superposition in time of overlapping hybrid events. We studied data from a small aperture seismic array. Data analysis for tremor and hybrids included: (1) spectral analysis; (2) apparent slowness and back-azimuth determination by using the zero-lag cross-correlation method; and (3) polarization analysis. Both types of events share these common features: (a) two dominant spectral bands at frequencies 1-3 Hz (the most energetic) and 4-8 Hz; (b) several coherent phases with the same back-azimuth to the source and apparent slowness along the whole signal; (c) in the high frequency band, the apparent slowness is very low (around 0.17 s/km), indicating the propagation of body waves; (d) in the low frequency band, the apparent slowness is high (around 1.6 s/km), consistent with the presence of surface waves; and (e) clear P-wave onset followed by a complex pattern of Rayleigh waves. Therefore, both types of events are strongly related because they share the same source region, the same wave-propagation properties, and the same wave composition. Moreover, several arrivals, that resemble a single hybrid event, have been found along the tremor signals. Due to these reasons, we hypothesize that volcanic tremor of Deception Island is a superposition of hybrid type events. The source of both types could be the interaction between thaw water and hot materials in a shallow aquifer.

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The 3D Attenuation Structure of Deception Island (Antarctica)

et al. 2015

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The seismic and volcanological structure of Deception Island (Antarctica) is an intense focus topic in Volcano Geophysics. The interpretations given by scientists on the origin, nature, and location of the structures buried under the island strongly diverge. We present a high-resolution 3D P-wave attenuation tomography model obtained by using the coda normalization method on 20,293 high-quality waveforms produced by active sources. The checkerboard and synthetic anomaly tests guarantee the reproduction of the input anomalies under the island down to a depth of 4 km. The results, once compared with our current knowledge on the geological, geochemical, and geophysical structure of the region, depict Deception as a piecemeal caldera structure coming out of the Bransfield Trough. Highattenuation anomalies contouring the northeastern emerged caldera rim correlate with the locations of sediments. In our interpretation, the main attenuation contrast, which appears under the collapsed southeastern caldera rim, is related to the deeper feeding systems. A unique P-wave high-attenuation spherical-like anomaly in the inner bay extends between depths of 1 and 3 km. The northern contour of the anomaly coincides with the calderic rim both at 1 and 2 km, while smaller anomalies connect it with deeper structures below 3 km, dipping toward the Bransfield Trough. In our interpretation, the large upper anomaly is caused by a high-temperature shallow (1-3 km deep) geothermal system, located beneath the sediment-filled bay in the collapsed blocks and heated by smaller, deeper contributions of molten materials (magma) rising from southeast.

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Attenuation and source parameters at Deception Island (South Shetland Islands, Antarctica)

Cited by 23 publications

References 21 publications

Analysis of the Temporal Occurrence of Seismicity at Deception Island (Antarctica). A Nonlinear Approach

Analysis of the Temporal Occurrence of Seismicity at Deception Island (Antarctica). A Nonlinear Approach

Array tracking of the volcanic tremor source at Deception Island, Antarctica

The 3D Attenuation Structure of Deception Island (Antarctica)

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