Remote monitoring of building oscillation modes by means of real-time Mid Infrared Digital Holography

Non-destructive measurements of deformations are a quite common application of holography but due to the intrinsic limits in the interferometric technique, those are generally confined only to small targets and in controlled environment. Here we present an advanced technique, based on Mid Infrared Digital Holography (MIR DH), which works in outdoor conditions and provides remote and real-time information on the oscillation modes of large engineering structures. Thanks to the long wavelength of the laser radiation, large areas of buildings can be simultaneously mapped with sub-micrometric resolution in terms of their amplitude and frequency oscillation modes providing all the modal parameters vital for all the correct prevention strategies when the functionality and the health status of the structures have to be evaluated. The existing experimental techniques used to evaluate the fundamental modes of a structure are based either on seismometric sensors or on Ground-based Synthetic Aperture Radar (GbSAR). Such devices have both serious drawbacks, which prevent their application at a large scale or in the short term. We here demonstrate that the MIR DH based technique can fully overcome these limitations and has the potential to represent a breakthrough advance in the field of dynamic characterization of large structures

chapter 9 thermal acoustic and seismic signals from pyroclastic density currents and vulcanian explosions at soufriere hills volcano montserrat

Abstract We show two examples of how integrated analysis of thermal and infrasound signal can be used to obtain, in real time, information on volcanic activity. Soufriere Hills Volcano (SHV) on Montserrat offers the opportunity to study a large variety of processes related to lava-dome activity, such as pyroclastic density currents (PDCs) and large Vulcanian eruptions. Infrasound and thermal analysis are used to constrain the propagation of PDCs and their velocities, which are calculated here to range between 15 and 75 m s −1 . During the Vulcanian eruption of 5 February 2010, infrasound and thermal records allow us to identify an approximately 13 s seismic precursor possibly related to the pressurization of the conduit before the explosion onset. The associated very long period (VLP) seismic signal is correlated with the gas-thrust phase detected by thermal imagery, and may reflect a change in the upward momentum induced by the mass discharge. Moreover, from infrasound and thermal analysis, we estimate a gas-thrust phase lasting 22 s, with an initial plume velocity of approximately 170 m s −1 and a mean volumetric discharge rate of 0.3×10 5 –9.2×10 5 m 3 s −1 . This information provided in real time gives important input parameters for modelling the tephra dispersal into the atmosphere

Forecasting Effusive Dynamics and Decompression Rates by Magmastatic Model at Open-vent Volcanoes

Effusive eruptions at open-conduit volcanoes are interpreted as reactions to a disequilibrium induced by the increase in magma supply. By comparing four of the most recent effusive eruptions at Stromboli volcano (Italy), we show how the volumes of lava discharged during each eruption are linearly correlated to the topographic positions of the effusive vents. This correlation cannot be explained by an excess of pressure within a deep magma chamber and raises questions about the actual contributions of deep magma dynamics. We derive a general model based on the discharge of a shallow reservoir and the magmastatic crustal load above the vent, to explain the linear link. In addition, we show how the drastic transition from effusive to violent explosions can be related to different decompression rates. We suggest that a gravity-driven model can shed light on similar cases of lateral effusive eruptions in other volcanic systems and can provide evidence of the roles of slow decompression rates in triggering violent paroxysmal explosive eruptions, which occasionally punctuate the effusive phases at basaltic volcanoes

Low-Energy Fragmentation Dynamics at Copahue Volcano (Argentina) as Revealed by an Infrasonic Array and Ash Characteristics

Ash-rich eruptions represent a serious risk to the population living nearby as well as at thousands of kilometers from a volcano. Volcanic ash is the result of extensive magma fragmentation during an eruption, and it depends upon a combination of magma properties such as rheology, vesicularity and permeability, gas overpressure and the possible involvement of external fluids during magma ascent. The explosive process generates infrasonic waves which are directly linked to the outflow of the gas-particle mixture in the atmosphere. The higher the overpressure in the magma, the higher should be the exit velocity of the ejected material and the acoustic pressure related to this process. During violent eruptions, fragmentation becomes more efficient and is responsible for the extensive production of ash which is dispersed in the atmosphere. We show that the phase of intense ash emission that occurred during March 2016 at Copahue volcano (Argentina) generated a very low (0.1 Pa) infrasonic amplitude at 13 km, raising a number of questions concerning the links among acoustic pressure, gas overpressure and efficiency of magma fragmentation. Infrasound and direct observations of the eruptive plume indicate that the large quantity of ash erupted at Copahue was ejected with a low exit velocity. Thus, it was associated with eruptive dynamics driven by a low magma overpressure. This is more evident when infrasonic activity at Copahue is compared to the moderate explosive activity of Villarrica (Chile), recorded by the same array, at a distance of 193 km. Our data suggest a process of rigid fragmentation under a low magma overpressure which was nearly completely dissipated during the passage of the erupting mixture through the granular, ash-bearing crater infilling. We conclude that ash released into the atmosphere during low-energy fragmentation dynamics can be difficult to monitor, with direct consequences for the assessment of the related hazard and management of eruptive crises.Fil: Hantusch, Marcia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Lacanna, Giorgio. Università degli Studi di Firenze; ItaliaFil: Ripepe, Maurizio. Università degli Studi di Firenze; ItaliaFil: Montenegro, Verónica Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Valderrama, Oscar. Servicio Nacional de Geologia y Mineria (SERNAGEOMIN); ChileFil: Farias, Camila Belen. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; ArgentinaFil: Caselli, Alberto Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Gabellini, Pietro. Università degli Studi di Firenze; ItaliaFil: Cioni, Raffaello. Università degli Studi di Firenze; Itali

Ground deformation reveals the scale-invariant conduit dynamics driving explosive basaltic eruptions

The mild activity of basaltic volcanoes is punctuated by violent explosive eruptions that occur without obvious precursors. Modelling the source processes of these sudden blasts is challenging. Here, we use two decades of ground deformation (tilt) records from Stromboli volcano to shed light, with unprecedented detail, on the short-term (minute-scale) conduit processes that drive such violent volcanic eruptions. We find that explosive eruptions, with source parameters spanning seven orders of magnitude, all share a common pre-blast ground inflation trend. We explain this exponential inflation using a model in which pressure build-up is caused by the rapid expansion of volatile-rich magma rising from depth into a shallow (<400m) resident magma conduit. We show that the duration and amplitude of this inflation trend scales with the eruption magnitude, indicating that the explosive dynamics obey the same (scale-invariant) conduit process. This scale-invariance of pre-explosion ground deformation may usher in a new era of short-term eruption forecasting

Ground deformation reveals the scale-invariant conduit dynamics driving explosive basaltic eruptions

The mild activity of basaltic volcanoes is punctuated by violent explosive eruptions that occur without obvious precursors. Modelling the source processes of these sudden blasts is challenging. Here, we use two decades of ground deformation (tilt) records from Stromboli volcano to shed light, with unprecedented detail, on the short-term (minute-scale) conduit processes that drive such violent volcanic eruptions. We find that explosive eruptions, with source parameters spanning seven orders of magnitude, all share a common pre-blast ground inflation trend. We explain this exponential inflation using a model in which pressure build-up is caused by the rapid expansion of volatile-rich magma rising from depth into a shallow (<400 m) resident magma conduit. We show that the duration and amplitude of this inflation trend scales with the eruption magnitude, indicating that the explosive dynamics obey the same (scale-invariant) conduit process. This scale-invariance of pre-explosion ground deformation may usher in a new era of short-term eruption forecasting

Tsunami risk management for crustal earthquakes and non-seismic sources in Italy

publishedVersio

The Stromboli geophysical experiment. Preliminary report on wide angle refraction seismics and morphobathymetry of Stromboli Island (Southern Tyrrhenian Sea, Italy) based on integrated offshore-onshore data acquisition (Cruise STR06 R/V URANIA)

Cruise STR06 on R/V Urania was performed in the framework of the ”INGV - DPC V2 - Monitoring and research activity at Stromboli and Panarea - Unit V2/03”, and resulted as a joint initiative between CNR (IAMC, Napoli and ISMAR, Bologna), INGV (Roma2, Osservatorio Vesuviano, Catania, Gibilmanna-CNT), University of Firenze and DPC, aiming to produce a seismic tomography of the Stromboli volcano, South Eastern Tyrrhenian Sea [Fig.1], and have insights into its 2-D structure and magma chambers. Cruise work plan was designed to extend at sea the existing Seismographic Network, complemented by several mobile stations, and to generate seismic shots by air-gun tuned array. 10 OBS were deployed around Stromboli, along the NE, SE and SW flanks of the volcano, according to (a) morphobathymetric analysis of available and newly produced DTMs, (b) modeling and (c) optimal lineaments with on-land recording stations. Seismic shots along radial and circle lines were obtained by a 4 GI-GUN 105+105 C.I. tuned array, while the absolute shot time was recorded at the resolution of ms. A request for ship time of R/V Uraniawas presented by IAMC, and a period of 7 days, including 2 day of transit was assigned to the project by CNR and scheduled for late November 2006. Cruise STR06 started in Naples 2006-11-27 and ended in Naples 2006-12-06. This paper reports the shipboard activities during the cruise STR06 on R/V Urania and some preliminary results regarding also the onshore activities carried out in order to perform the Stromboli geophysical experiment. A description of the ship, equipment and their usage is given thereinafter, along with details of the general settings, performances and some scientific and technical results.Istituto di Scienze Marine, ISMAR-CNR, BolognaPublished3.6. Fisica del vulcanismo1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attiveope

The Stromboli geophysical experiment. Preliminary report on wide angle refraction seismics and morphobathymetry of Stromboli Island (Southern Tyrrhenian Sea, Italy) based on integrated offshore-onshore data acquisition (Cruise STR06 R/V URANIA)

Cruise STR06 on R/V Urania was performed in the framework of the ”INGV - DPC V2 - Monitoring and research activity at Stromboli and Panarea - Unit V2/03”, and resulted as a joint initiative between CNR (IAMC, Napoli and ISMAR, Bologna), INGV (Roma2, Osservatorio Vesuviano, Catania, Gibilmanna-CNT), University of Firenze and DPC, aiming to produce a seismic tomography of the Stromboli volcano, South Eastern Tyrrhenian Sea [Fig.1], and have insights into its 2-D structure and magma chambers. Cruise work plan was designed to extend at sea the existing Seismographic Network, complemented by several mobile stations, and to generate seismic shots by air-gun tuned array. 10 OBS were deployed around Stromboli, along the NE, SE and SW flanks of the volcano, according to (a) morphobathymetric analysis of available and newly produced DTMs, (b) modeling and (c) optimal lineaments with on-land recording stations. Seismic shots along radial and circle lines were obtained by a 4 GI-GUN 105+105 C.I. tuned array, while the absolute shot time was recorded at the resolution of ms. A request for ship time of R/V Uraniawas presented by IAMC, and a period of 7 days, including 2 day of transit was assigned to the project by CNR and scheduled for late November 2006. Cruise STR06 started in Naples 2006-11-27 and ended in Naples 2006-12-06. This paper reports the shipboard activities during the cruise STR06 on R/V Urania and some preliminary results regarding also the onshore activities carried out in order to perform the Stromboli geophysical experiment. A description of the ship, equipment and their usage is given thereinafter, along with details of the general settings, performances and some scientific and technical results