ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Unbekannt

Depth of a Midcrustal Discontinuity beneath Mt. Vesuvius from the Stacking of Reflected and Converted Waves on Local Earthquake Records (2005)

Nisii, V. ; Zollo, A. ; Iannaccone, G.

The Seismological Society of America

zur Merkliste hinzufügen auf der Merkliste

Details

Publikationsdatum: 2017-04-04

Beschreibung: We have developed a technique based on the move-out and stack of reflected seismic phases from local earthquake seismograms. For a given interface depth and a velocity model, the theoretical travel times of reflected/converted phases in a 1D medium are computed and used to align in time the vertical-component microearthquake records collected by a local seismic network. The locations and origin times of events are preliminarily estimated from P and S arrival times. Different seismic gathers are obtained for each considered reflected/converted phase at that interface, and the best interface depth is chosen as the one that maximizes the value of a semblance function computed on moved-out records. This method has been applied to seismic records of microearthquakes that occur at Mt. Vesuvius volcano. The analysis confirms the evidence for an 8 to 10-km-deep seismic discontinuity beneath the volcano, which was previously identified, by migration of active seismic data, as the roof of an extended magmatic sill.

Beschreibung: Published

Beschreibung: 1842-1849

Beschreibung: partially_open

Schlagwort(e): Mt. Vesuvius ; Midcrustal discontinuity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 05. General::05.01. Computational geophysics::05.01.01. Data processing

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

Format: 469 bytes

Format: 619799 bytes

Format: text/html

Format: application/pdf

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

ARTIKEL (OA)

S·F·X

PDF

Volltext

2

Unbekannt

Time reverse location of seismic long-period events recorded on Mt Etna (2012)

O’Brien, G. S. ; Lokmer, I. ; De Barros, L. ; [weitere]

Wiley

zur Merkliste hinzufügen auf der Merkliste

Details

Publikationsdatum: 2017-04-04

Beschreibung: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.

Beschreibung: Published

Beschreibung: 452-462

Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive

Beschreibung: JCR Journal

Beschreibung: reserved

Schlagwort(e): Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

ARTIKEL (OA)

S·F·X

PDF

Volltext

3

Unbekannt

Depth-dependent intrinsic and scattering seismic attenuation in north central Italy (2011)

Del Pezzo, E. ; Bianco, F. ; Marzorati, S. ; [weitere]

Wiley

zur Merkliste hinzufügen auf der Merkliste

Details

Publikationsdatum: 2017-04-04

Beschreibung: In this study the attenuation mechanism of seismic wave energy in north central Italy is estimated using low-magnitude earthquake local data recorded at six stations managed by INGV. Most of the analysed events are located along the Alpine chain in the zone of Iseo and Garda lakes, while a minor part in the Po valley. The zone investigated is characterized by the occurrence of significantly intense earthquakes (magnitude up to 6.6) the most recent occurred in 2004 close to the city of Sal`o on the coast of the Garda lake (Mw = 5.0). Due to the high population density and presence of industrial activity the investigated area is characterized by a high seismic risk. First, the ordinary Multiple Lapse Time Window Analysis (MLTWA) method is applied in the assumption of uniformvelocity and scattering and the couple of B0, the seismic albedo and Le−1, the extinction length inverse (corresponding to the total attenuation coefficient) is calculated in the frequency bands of 1.5, 3, 6 and 12 Hz. To retrieve more realistic estimates, the obtained values of B0 and Le−1 are corrected taking into account the effects of a depth-dependent earth model, consisting of an earth structure characterized by a transparent upper mantle and a heterogeneous crust. We find that the corrected intrinsic and scattering attenuation parameters (which are proportional to the inverse of the intrinsic/scattering quality factors, QI−1 and Qs−1) are strongly frequency dependent, with a prevalence of scattering attenuation over the intrinsic dissipation. The corrected and uncorrected values of total Q are in agreement with the total Q values obtained with different approaches for the same area.

Beschreibung: Published

Beschreibung: 3.1. Fisica dei terremoti

Beschreibung: JCR Journal

Beschreibung: reserved

Schlagwort(e): Seismic Attenuation ; Coda Waves ; Wave Scattering and Diffraction ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

ARTIKEL (OA)

S·F·X

PDF

Volltext

4

Unbekannt

Time reverse location of seismic long-period events recorded on Mt Etna (2011)

O’Brien, G. S. ; Lokmer, I. ; De Barros, L. ; [weitere]

Wiley

zur Merkliste hinzufügen auf der Merkliste

Details

Publikationsdatum: 2017-04-04

Beschreibung: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.

Beschreibung: In press

Beschreibung: (11)

Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive

Beschreibung: JCR Journal

Beschreibung: reserved

Schlagwort(e): Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

ARTIKEL (OA)

S·F·X

PDF

Volltext

5

Unbekannt

Issues in Choosing the References to Use for Spectral Ratios from Observations and Modeling at Cavola Landslide in Northern Italy (2011)

Bordoni, P. ; Di Giulio, G. ; Haines, J. A. ; [weitere]

The Seismological Society of America

zur Merkliste hinzufügen auf der Merkliste

Details

Publikationsdatum: 2017-04-04

Beschreibung: A reference site has to be free of amplification or de-amplification effects, namely with no troughs and peaks in its Fourier amplitude spectrum. At the Cavola landslide we show that this spectrum is dependent on the direction of propagation of wave fronts for incidence angles in the range 30° to 90°. Our study is based on comparison of spectral ratios from observations and 2D numerical simulations. We have modeled propagation in a 2D profile for SH and SV waves with several incidence angles in the 0° ±90° range, where 0° and 90° are respectively vertical and horizontal incidence, except that ±90° denotes Rayleigh waves in the P-SV. We discuss in detail the result for angles of incidence of 0, ±20°, ±60°, ±90°. We have obtained observed horizontal-to-horizontal earthquakes spectral ratios using three reference sites. Two of these have matching receivers in the model, located at the opposite ends of the 2D profile. Overall observations are matched best when the reference site is located on the same side of the landslide as the incoming wave front. We also find general agreement of the observed H/H spectral ratios from earthquakes with H/V and H/H spectral ratios from noise, and the match between H/V values from noise and synthetic spectral ratios using an absolute, flat half-space reference is very good. On the other hand, 1D modeling performs poorly in comparison with 2D modeling in our case, for which the shape ratio h/D = 0.2 is intermediate between primarily-1D and strongly-2D wave propagation according to the classification of Bard and Bouchon (1985).

Beschreibung: The (1) Area Ambiente e Sviluppo Sostenibile of Provincia di Modena, (2) Area Pianificazione e Tutela del Territorio of Provincia di Reggio Emilia, (3) Servizio Tecnico of Comune di Toano, and (4) Servizio Geologico, Sismico e dei Suoli of Regione Emilia Romagna, (5) INGV-CNT.

Beschreibung: Published

Beschreibung: 1578–1613

Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica

Beschreibung: JCR Journal

Beschreibung: reserved

Schlagwort(e): reference site, 2D modeling, spectral ratios, noise, ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

Permalink