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  • 1
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    Modelling of the April 5, 2003 Stomboli (Italy), paroxysmal eruption from the inversion of broadband seismic data (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On April 5, 2003, one of the largest eruptions in the last decades was observed at Stromboli volcano, Italy. The eruption occurred in a period of increased volcanic activity, following a first explosion in December 2002, which interrupted the typical moderate “Strombolian” behaviour. We present an exhaustive analysis of the available broadband seismic data and relate them to the observed eruption phases. Prominent features of the seismic signals include an ultra long period signal starting a few tens of seconds prior to the explosive eruption as well as a strong energetic signal a few seconds after the onset of the eruption. Both signals are not exactly synchronized with the other geophysical observations. We present a detailed study of those signals using spectral and particle motion techniques. We estimate eruption parameters and seismic source characteristics by different inversion approaches. Results clearly indicate that the paroxysmal eruption was triggered by a shallow slow thrust-faulting dislocation event with a moment magnitude of Mw=3.0 and possibly associated with a crack that formed previously by dike extrusion. At least one blow-out phase during the paroxysmal explosion could be identified from seismic signals with an equivalent moment magnitude of Mw=3.7 and is represented by a vertical linear vector dipole and two weaker horizontal linear dipoles in opposite direction, plus a vertical force.
    Description: Published
    Description: 164-178
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; source inversion ; volcano seismology ; paroxysm ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Modeling of the source mechanism of the April 5, 2003 paroxysmal eruption at Stromboli volcano (Italy) by the inversion of broadband seismic data (2007)
    Details
    Publication Date: 2017-04-04
    Description: Abstract: On April 5, 2003, one of the largest eruptions in the last decades was observed at Stromboli volcano, Italy. The eruption occurred in a period of anomalous volcanic activity, after a previous explosion in December 2002 interrupted the typical moderate "Strombolian" behaviour. An exhaustive analysis of the available broadband seismic data is here presented and related to the observed eruption phases. Prominent features of the seismic signals include a very long period signal a few tens of seconds prior to the explosive eruption, as well as a strong energetic signal a few seconds after the onset of the eruption.
    Description: Published
    Description: San Francisco
    Description: 3.1. Fisica dei terremoti
    Description: open
    Keywords: source inversion ; Stromboli ; volcano seismology ; paroxysm ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 3
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    Interaction of seismic and airwaves recorded at Stromboli volcano (2007)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Explosion-quake seismograms recorded at Stromboli show that seismic phases with a high-amplitude and high-frequency content propagate with a velocity of approximately 330 m/s - the sound speed. The analysis of seismograms, recorded at a distance of 500 m from one of the three active vents, shows for the first onset a low frequency and particle motion characteristics of a p-wave, which loses its longitudinal polarization with the onset of the air-wave. Recording the explosion-quake simultaneously with a microphonewe would ascertain that the high frequency onset coincides with the air-wave's. In order to better understand the seismic wavefield generated by the atmospheric pressure, we performed a controlled source experiment at Stromboli using a seismic gun. Seismograms with the same two phases and particle motions comparable with the volcanic seismic data were obtained. A second experiment demonstrated, that the air-wave propagates at least in the uppermost 1m of the gound. We suggest that the seismic source of the corresponding seismograms is an explosion at the top of the magma column and conclude that the p- and air-waves are both generated in the same point and at the same time.
    Description: Published
    Description: 65-68
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: volcano seismology ; Stromboli ; air wave ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Air-wave phases in strombolian explosion quake seismograms: a possible indicator for the magma level? (2015)
    Details
    Publication Date: 2017-04-04
    Description: Many explosion-quake seismograms recorded near the active craters at Stromboli are dominated by two distinct onsets: a first low-frequency phase and a second high-frequency one. Particle-motion diagrams show a P-wave characteristic for the low-frequency phase, whereas in the high-frequency onset the longitudinal polarization is lost and the pattern becomes chaotic in the horizontal as well as in the vertical plane. The air-pressure pulse generated by the volcanic explosion is detected by the seismometer as a high-frequency signal, and we assume as source mechanism an explosion at the top of the magma column, generated by rising gas bubbles. The different path lengths and velocities for the seismic wave and the air-wave are the reasons for the difference in arrival times Dt between the low-frequency and the high-frequency onset. We tried to deduce the magma level and gas velocity in the conduit, from observed Dt values. If the pressure pulse inside the consuit is assumed yo be lower (30-70 m/s) than the sound speed, the magma level remains reasonably stable, even for large changes of Dt.
    Description: Published
    Description: 201-206
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: N/A or not JCR
    Description: restricted
    Keywords: Stromboli ; volcano seismology ; air-wave ; seismic source ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Highlights from a seismic broadband array on Stromboli (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: An array of nine three-component broadband seismometers was deployed in two different configurations on Stromboli volcano. The analysis of the seismic wavefield related to volcanic explosions revealed some observations which offer a completely new insight into the internal dynamics of a volcano. These new observations are restricted to the low-frequency range below 1 Hz and underline, therefore, the superiority of broadband recordings over conventional short-period observations. Surprisingly simple wavelets indicate an initially contracting source mechanism. Gas-jets that could not be seen in a short-period seismic record at all, generate a clear dilatational wavelet in a broadband recording suggesting the same contracting source mechanism. The analysis of particle motion and seismic array techniques permits a location of the seismic source. We find low-frequency signals of 3s and 6s period that are not related to eruptions and do not share a common source with the eruption-related events. A video recording of visible volcanic activity at the crater region allows one to correlate precisely eruptive features with seismic signals.
    Description: Published
    Description: 749-752
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: N/A or not JCR
    Description: restricted
    Keywords: Stromboli ; volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Infrasonic waves and volcanic tremor at Stromboli (2015)
    Details
    Publication Date: 2017-04-04
    Description: The origin of the volcanic tremor is still under debate. Many theories have been proposed in the last years, but none has yet been completely accepted. In 1993, highly sensitive pressure sensors (2.175 Pa/Volt) used to monitor the explosive activity have revealed unexpected correlation between small spike-shaped pressure signals (1-2 Pa) and volcanic tremor. These pressure pulses repeat regularly in time with a recurrent period of ca. 1s. Video camera images allowed us to correlate the pressure pulses with small gas bursts occurring at one of the active vents. The striking correlation (0.971) between infrasonic and seismic energy fluctuations is particularly meaningful in the frequency domain. Infrasonic and seismic signals share the same spectral content (3Hz) for every station within a range of 700 m around the craters. Correlations in time and frequency domain remained unaltered during the 1994 field experiments. Moreover, during 1994, the increased degassing activity has been followed by an increase in pressure release (7-8 Pa) and by a shift towards higher frequencies (8Hz) both in the infrasonic and seismic records. Infrasonic waves and volcanic tremor show similar energy fluctuations and frequency contents, appearing therefore produced by the same dynamical process. On this basis we claim the volcanic tremor at Stromboli originates by continuous outbursting of small gas bubbles in the upper part of the magmatic column.
    Description: Published
    Description: 181-184
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli ; volcano seismology ; volcanic tremor ; infrasound ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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