Tectonism and Its Relation to Magmatism Around Santorini Volcano From Upper Crustal <i>P</i> Wave Velocity

Heath, Benjamin; Hooft, E. E.; Toomey, D. R.; Papazachos, C. B.; Nomikou, Paraskevi; Paulatto, M.; Morgan, Joanna; Warner, Mike

doi:10.1029/2019jb017699

Cited by 32 publications

(97 citation statements)

References 70 publications

(164 reference statements)

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“…The sedimentary strata are generally associated with a rather gentle velocity increase from approximately 1.5 to 2.5 km/s, while the basement is associated with higher velocities in the order of 3.0 km/s. These values are mostly in agreement with the regional tomographic model presented by Heath et al (2019), who attribute metamorphic basement and sedimentary strata with to velocities higher or lower than 3.0 km/s, respectively (compare their Figure 5). However, a more detailed comparison of their results is not feasible as the presented velocity models are too coarsely resolved considering the high complexity of the data under consideration.…”

Section: Interpretation‐driven Refinementsupporting

confidence: 91%

“…Based on a recent active seismic tomography experiment, Heath et al (2019) and Hooft et al (2019) obtained tomographic P ‐wave velocity models for the upper crustal structure across Santorini Volcano and the surrounding region. In agreement with the previous tectonic models, they conclude that tectono‐magmatic lineaments control magma emplacement at Santorini and Kolumbo and that the initiation of basin formation predates the onset of volcanism.…”

Section: Geological Settingmentioning

confidence: 99%

“…In agreement with the previous tectonic models, they conclude that tectono‐magmatic lineaments control magma emplacement at Santorini and Kolumbo and that the initiation of basin formation predates the onset of volcanism. Heath et al (2019) inferred that the Anhydros Basin is of maximum 1.5‐km thickness and the Santorini‐Anafi Basin of maximum 2‐km thickness.…”

Section: Geological Settingmentioning

confidence: 99%

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When There Is No Offset: A Demonstration of Seismic Diffraction Imaging and Depth‐Velocity Model Building in the Southern Aegean Sea

et al. 2020

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A vast majority of marine geological research is based on academic seismic data collected with single-channel systems or short-offset multichannel seismic cables, which often lack reflection moveout for conventional velocity analysis. Consequently, our understanding of Earth processes often relies on seismic time sections, which hampers quantitative analysis in terms of depth, formation thicknesses, or dip angles of faults. In order to overcome these limitations, we present a robust diffraction extraction scheme that models and adaptively subtracts the reflected wavefield from the data. We use diffractions to estimate insightful wavefront attributes and perform wavefront tomography to obtain laterally resolved seismic velocity information in depth. Using diffraction focusing as a quality control tool, we perform an interpretation-driven refinement to derive a geologically plausible depth-velocity model. In a final step, we perform depth migration to arrive at a spatial reconstruction of the shallow crust. Further, we focus the diffracted wavefield to demonstrate how these diffraction images can be used as physics-guided attribute maps to support the identification of faults and unconformities. We demonstrate the potential of this processing scheme by its application to a seismic line from the Santorini Amorgos Tectonic Zone, located on the Hellenic Volcanic Arc, which is notorious for its catastrophic volcanic eruptions, earthquakes, and tsunamis. The resulting depth image allows a refined fault pattern delineation and, for the first time, a quantitative analysis of the basin stratigraphy. We conclude that diffraction-based data analysis has a high potential, especially when the acquisition geometry of seismic data does not allow conventional velocity analysis. Plain Language Summary The active seismic method is a standard tool for studying and imaging the Earth's lithosphere. Proper imaging of complex geological targets requires seismic data of excellent quality, which are typically only acquired with expensive industrial surveys. Academic surveys, however, are often restricted to marine seismic equipment with limited illumination, which compromises imaging and interpretation. While most of the contemporary processing and interpretational routines are tailored to the reflected wavefield, recent research suggests that the often overlooked diffracted wavefield might help to overcome the gap between academic and industrial seismic imaging. Wave diffraction is the response of the seismic wavefield to small-scale subsurface structures and allows to estimate velocities even from single-channel seismic data. In this study, we use an academic seismic profile from the southern Aegean Sea and extract a rich diffracted wavefield from the data. We utilize these diffractions to estimate a velocity model that permits a reconstruction of the subsurface in depth and specifically highlight discontinuous features related to past dynamic processes. Such depth images allow us to reliably measure thicknesses and fault angles. We con...

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Section: Interpretation‐driven Refinementsupporting

confidence: 91%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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When There Is No Offset: A Demonstration of Seismic Diffraction Imaging and Depth‐Velocity Model Building in the Southern Aegean Sea

et al. 2020

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“…three-dimensional magma storage regions with scales ranging from the upper few kilometers to the whole crust [15][16][17][18][19] . While there is promise for reliable local seismic tomography with modest numbers of instruments, these studies are still limited in their ability to image the full TCMS by the availability of local seismicity at mid-to-lower crustal depths [20][21][22] .…”

mentioning

confidence: 99%

Aseismic mid-crustal magma reservoir at Cleveland Volcano imaged through novel receiver function analyses

Janiszewski

Wagner

Roman

2020

Sci Rep

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processes related to eruptions at arc volcanoes are linked by structures that transect the entire crust. Imaging the mid-to lower-crustal portions (here, ~5-15 km and >15 km respectively) of these magmatic systems where intermediate storage may occur has been a longstanding challenge. Tomography, local seismic source studies, geodetic, and geochemical constraints, are typically most sensitive to shallow (<5 km) storage and/or have insufficient resolution at these depths. Geophysical methods are even further limited at frequently-erupting volcanoes where well-developed trans-crustal magmatic systems are likely to exist, due to a lack of deep seismicity. Here we show direct evidence for mid-crustal magma storage beneath the frequently erupting Cleveland volcano, Alaska, using a novel application of seismic receiver functions. We use p-s scattered waves from the Moho as virtual sources to investigate S-wave velocities between the Moho and the surface. our forward modeling approach allows us to provide direct constraints on the geometry of low velocity regions beneath volcanoes despite having a comparatively sparse seismic network. our results show clear evidence of mid-crustal magma storage beneath the depths of located volcanic seismicity. future work using similar approaches will enable an unprecedented comparative examination of magmatic systems beneath sparsely instrumented volcanoes globally. Recent research on trans-crustal magmatic systems (TCMS) demonstrates the importance of relationships between temporally longer-lived zones of crystals, melt, and volatiles ("mush") that extend throughout the crust, and comparatively ephemeral and depth-restricted magma reservoirs comprised primarily of eruptible melt 1 in driving volcanic eruptions. A longstanding barrier to understanding these systems is the challenge of imaging the mid-to lower-crustal portions of TCMS 1,2. Commonly-used approaches for detecting crustal magma reservoirs include analyses of volcanic seismicity, analyses of geodetic observations, and geochemical and petrological analyses of eruption products. Volcanic seismicity is linked to differential strain and pressure transfers related to magma and volatile movement in the crust and can either be similar to tectonic earthquakes (volcano-tectonic or VT events) or have primarily long period energy (LP events) 3-7. Similarly, geodetic methods constrain locations of magma storage by measuring deformation associated with magma emplacement and movement within the crust, and are typically most sensitive to shallow magma storage regions 8-10. Both methods are most sensitive to the results of magma movement; therefore, the absence of seismicity or geodetic deformation at volcanoes cannot be interpreted as the absence of stable magmatic (or mush) storage regions, limiting the ability of these techniques to provide information on comparatively stable volcanic systems. Geochemical and petrological approaches for assessing magma storage depths are most sensitive to the region of last storage in the crust prior t...

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“…For stationary-receiver surveys, coarse 3D passive/active-source OBS experiments begin to emerge in academia (Morgan et al, 2016;Goncharov et al, 2016;Heath et al, 2019;Arai et al, 2019). Sparse areal OBS deployments provide the necessary flexibility to design long-offset acquisition geometries, such that energetic diving waves and post-critical reflections could sample the deepest targeted-structures (lower crust, Moho, upper mantle).…”

mentioning

confidence: 99%

GO_3D_OBS – The Nankai Trough-inspired benchmark geomodel for seismic imaging methods assessment and next generation 3D surveys design (version 1.0)

Górszczyk

Operto

2020

Preprint

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Abstract. Detailed reconstruction of deep crustal targets by seismic methods remains a long-standing challenge. One key to address this challenge is the joint development of new seismic acquisition systems and leading-edge processing techniques. In marine environments, controlled-source seismic surveys at regional scale are typically carried out with sparse arrays of ocean bottom seismometers (OBSs), which provide incomplete and down-sampled subsurface illumination. To assess and minimize the acquisition footprint in high-resolution imaging process such as full waveform inversion, realistic crustal-scale benchmark models are clearly required.The deficiency of such models prompts us to build one and release it freely to the geophysical community. Here we introduce GO_3D_OBS – a 3D high-resolution geomodel representing a subduction zone, inspired by the geology of the Nankai Trough. The 175 km x 100 km x 30 km model integrates complex geological structures with a visco-elastic isotropic parametrization. It is defined in form of a uniform Cartesian grid containing 33.6e9 degrees of freedom for a grid interval of 25 m. The size of the model raises significant high-performance computing challenges to tackle large-scale forward propagation simulations and related inverse problems. We describe the workflow designed to implement all the model ingredients including 2D structural segments, their projection into the third dimension, stochastic components and physical parametrisation. Various wavefield simulations we present clearly reflect in the seismograms the structural complexity of the model and the footprint of different physical approximations. This benchmark model shall help to optimize the design of next generation 3D academic surveys – in particular but not only long-offset OBS experiments – to mitigate the acquisition footprint during high-resolution imaging of the deep crust.

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Tectonism and Its Relation to Magmatism Around Santorini Volcano From Upper Crustal P Wave Velocity

Cited by 32 publications

References 70 publications

When There Is No Offset: A Demonstration of Seismic Diffraction Imaging and Depth‐Velocity Model Building in the Southern Aegean Sea

When There Is No Offset: A Demonstration of Seismic Diffraction Imaging and Depth‐Velocity Model Building in the Southern Aegean Sea

Aseismic mid-crustal magma reservoir at Cleveland Volcano imaged through novel receiver function analyses

GO_3D_OBS – The Nankai Trough-inspired benchmark geomodel for seismic imaging methods assessment and next generation 3D surveys design (version 1.0)

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