The 1998–1999 seismic series at Deception Island volcano, Antarctica

Ibáñez, Jesús M.; Carmona, Enrique; Almendros, Javier; Saccorotti, Gilberto; Pezzo, E. Del; Abril, Miguel; Ortiz, R.

doi:10.1016/s0377-0273(03)00247-6

Cited by 56 publications

(70 citation statements)

References 31 publications

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“…Our interpretation of these apparent slowness vector results in terms of source position and characteristics is limited basically by the use of a single seismic array and our poor knowledge of the seismic velocity structure. Single‐array source locations rely on a proper representation of wave propagation through the medium [ Goldstein and Chouet , ; Almendros et al , ; Ibáñez et al , ], and thus, they are severely affected by uncertainties in the velocity model. On the other hand, multiple arrays allow for quantitative estimates of source locations [ Almendros et al , , ; Metaxian et al , ; La Rocca et al , ; Saccorotti et al , ; Di Lieto et al , ; Ryberg et al , ; Inza et al , ].…”

Section: Discussionmentioning

confidence: 99%

Array analysis of the seismic wavefield of long‐period events and volcanic tremor at Arenal volcano, Costa Rica

et al. 2014

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We use wavefield decomposition methods (time domain cross correlation and frequency domain multiple‐signal classification) to analyze seismic data recorded by a dense, small‐aperture array located 2 km West of Arenal volcano, Costa Rica, and operated during 2.5 days. The recorded wavefield is dominated by harmonic tremor and includes also spasmodic tremor and long‐period (LP) events. We find that the initial stages of LP events are characterized by three different wave arrivals. These arrivals propagate with similar back azimuths pointing to the volcano summit (∼80°N) and increasing apparent slowness of 0.4, 1.1, and 1.7 s/km. Spasmodic tremors cannot be regarded as coherent signals. On the contrary, harmonic tremors are highly coherent, characterized by the stability of the apparent slowness vector estimates. Apparent slowness lays in the range 1–2 s/km. Back azimuths point in the general direction of the volcano but with a large variability (40–120°N). Nevertheless, there are long‐term variations and evidences of multiple simultaneous components in the harmonic tremor wavefield. These observations suggest that LP events and tremor are generated in a shallow source area near the volcano summit, although they do not share exactly the same source region or source processes. The tremor source is located in the shallowest part of the plumbing system, beneath the lava crust. This dynamic region is subject to complex fluctuations of the physical conditions. Degassing events at different locations of this region might generate variable seismic radiation patterns. The effects of topography and heterogeneous shallow structure of the volcano may amplify these variations and produce the wide directional span observed for volcanic tremor. On the other hand, the LP source seems to be more repeatable. LP events are likely triggered by fragmentation of the fluid flow in a slightly deeper portion of the volcanic conduits.

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Section: Discussionmentioning

confidence: 99%

Array analysis of the seismic wavefield of long‐period events and volcanic tremor at Arenal volcano, Costa Rica

et al. 2014

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“…The study of the seismic activity of the volcano is probably the most active and productive research line, as reported by Tejedo et al (2014). There are many results that help us better understand the dynamic and volcanological framework of the area, such as Vila et al (1992), , Ibáñez et al (1997Ibáñez et al ( , 2000Ibáñez et al ( , 2003, Saccorotti et al (2001), Martinez-Arevalo et al (2003), Benitez et al (2007), Carmona et al (2010Carmona et al ( , 2012Carmona et al ( , 2014, and García-Yeguas et al (2010). One of the objectives of these seismic studies is to provide 2D or 3D structure of the area, by using active or passive data as has been done by Ben-Zvi et al (2009), Zandomeneghi et al (2009), and Prudencio et al (2013).…”

Section: Introductionmentioning

confidence: 99%

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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“…In order to emphasize the performance of the RelSE method, we use both ACC and RelSE slowness vector estimates (Tables 1 and 2, respectively). The S ‐ P times and velocity model are the same used by Ibáñez et al [2003b]. Figure 16 shows the calculated source locations.…”

Section: Discussionmentioning

confidence: 99%

“…Figure 16 shows the calculated source locations. ACC solutions (solid dots) were already obtained by Ibáñez et al [2003b] in their analyses of the 1999 Deception Island earthquakes. They are contained within a small region northeast of the array site.…”

Section: Discussionmentioning

confidence: 99%

“…For this work, we take advantage of the fact that some of the Deception Island earthquakes display very similar waveforms. Although site effects at a seismic station may induce resembling waveforms for virtually any earthquake, the occurrence of earthquakes with very different waveforms as well [ Ibáñez et al , 2003b] ensures that waveform similarity is intrinsically associated with the earthquake source. E. Carmona et al (Characterization of fracture systems using precise array locations of earthquake multiplets recorded at Deception Island volcano, Antarctica, manuscript in preparation, 2004) grouped the earthquake data set in multiplets using the equivalence‐class approach [ Aster and Scott , 1993; Maurer and Deichmann , 1995] and a cross‐correlation technique [ Saccorotti et al , 2002] that compares both the P and S waveforms recorded at the central station of the array.…”

Section: Application To Real Datamentioning

confidence: 99%

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Precise determination of the relative wave propagation parameters of similar events using a small‐aperture seismic array

2004

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[1] We propose a method to determine accurately the relative wave propagation parameters (apparent slowness and propagation azimuth) of a cluster of seismic events with similar waveforms recorded on a seismic array. This relative slowness estimate (RelSE) method is based on precise measurements of the delays among arrivals of different earthquakes to each of the array receivers. Delays are determined using interpolations of the cross-correlation functions of the earthquake waveforms. Accurate relative slowness vectors are estimated using a least squares fit of the observed delays to the delays corresponding to the arrivals of plane wave fronts. We tested the method using both synthetics and real data, in order to understand its resolution capabilities in presence of seismic noise and to assess the uncertainty regions associated with the slowness vector estimates. From these analyses, we establish a procedure to determine the 90% uncertainty regions associated with the estimates of relative slowness vectors. As an example of application of the RelSE method, we analyzed a multiplet composed of 16 similar earthquakes recorded during the 1999 seismic crisis at Deception Island volcano, Antarctica. Using a conventional slowness estimate method produces virtually the same result for every earthquake, because of the large uncertainties. Alternatively, using the RelSE method reduces the uncertainties of the estimates and allows to resolve the detailed distribution of (relative) apparent slowness vectors. Our results show that the slowness vectors are aligned within a narrow, north-south trending band, which represents a clue toward the features of the source region and/or source distribution. We repeated the procedure using different earthquakes as master events. The estimated distribution of slowness vectors is similar in every case, which demonstrates that our results are independent of the choice of reference event.INDEX TERMS: 7299 Seismology: General or miscellaneous; 7203 Seismology: Body wave propagation; 7215 Seismology: Earthquake parameters; 7230 Seismology: Seismicity and seismotectonics; 7280 Seismology: Volcano seismology (8419); KEYWORDS: seismic arrays, slowness vectors, multiplet analysis, Deception Island volcano Citation: Almendros, J., E. Carmona, and J. Ibáñez (2004), Precise determination of the relative wave propagation parameters of similar events using a small-aperture seismic array,

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The 1998–1999 seismic series at Deception Island volcano, Antarctica

Cited by 56 publications

References 31 publications

Array analysis of the seismic wavefield of long‐period events and volcanic tremor at Arenal volcano, Costa Rica

Array analysis of the seismic wavefield of long‐period events and volcanic tremor at Arenal volcano, Costa Rica

The 3D Attenuation Structure of Deception Island (Antarctica)

Precise determination of the relative wave propagation parameters of similar events using a small‐aperture seismic array

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