{ "schemaVersion": 1, "researchDate": "2026-10-09", "status": "PRIMARY_SOURCE_RESEARCH_NOT_AN_EVENT_VALIDATION", "event": "2018-12-26T02:19:14Z, Fiandaca, INGV event 21285011", "conclusion": "Published Etna attenuation and density constraints exist, but no retrieved, licensed, colocated 3D rho/Qp/Qs field directly validates a 0.2–1 Hz deterministic Fiandaca simulation. Preserve the De Gori Vp and Vs independently; density and attenuation remain explicit alternative assumptions.", "density": { "brocher2005": { "doi": "10.1785/0120050077", "primaryRecord": "https://pubs.usgs.gov/publication/70027956", "authorUploadedFullText": "https://www.researchgate.net/publication/246547514_Empirical_Relations_between_Elastic_Wavespeeds_and_Density_in_the_Earth's_Crust", "locator": "BSSA 95(6), 2081–2092; page2082, equation1", "equation": "rho_g_cm3 = 1.6612*Vp - 0.4721*Vp^2 + 0.0671*Vp^3 - 0.0043*Vp^4 + 0.000106*Vp^5", "inputUnit": "Vp in km/s", "outputUnit": "g/cm^3; multiply by1000 for kg/m^3", "validVpRangeKms": [ 1.5, 8.5 ], "basis": "Polynomial fit to handpicked Nafe–Drake density/velocity curve; a crustal empirical prior, not an Etna density observation.", "deGoriCompatibility": "Published Vp range2.28–7.81km/s lies within the equation interval. Use published Vs, rather than replacing it with another Vp–Vs regression.", "sensitivityRecommendation": "Baseline rho(Vp), then separately freeze factors0.9/1.1 and, if required,0.8/1.2. These factors are analyst-selected sensitivity tests, not statistical confidence bounds.", "caution": "Brocher equation6 for Vs excludes mafic/calcium-rich lithologies, gabbros and serpentinites; do not transfer that exclusion to equation1 or use equation6 instead of available Vs. Density is not uniquely determined by Vp." }, "christensenMooney1995": { "doi": "10.1029/95JB00259", "primaryUrl": "https://agupubs.onlinelibrary.wiley.com/doi/10.1029/95JB00259", "reportedBy": "Brocher2005 page2082 equation3", "equation": "rho_g_cm3 = 0.541 + 0.3601*Vp_km_s", "validVpRangeKms": [ 5.5, 7.5 ], "scope": "Crystalline crust at10km; excludes volcanic and monomineralic rocks in Brocher’s description.", "decision": "Do not apply indiscriminately throughout shallow volcanic Etna or extrapolate down to Vp2.28km/s." }, "etna3DGravity2007": { "citation": "Schiavone and Loddo2007, 3-D density model of Mt.Etna Volcano (Southern Italy), JVGR164,161–175", "doi": "10.1016/j.jvolgeores.2007.04.016", "primaryRecord": "https://ricerca.uniba.it/handle/11586/80517", "publisherUrl": "https://www.sciencedirect.com/science/article/abs/pii/S0377027307001345", "scope": "3D gravity inversion of observations from the1980s, with density contrasts and high/low density bodies; not a direct density scan.", "downloadableGridFound": false, "license": "No associated files or reusable grid license provided by the inspected UniBa record.", "compatibility": "Older epoch and gravity-inversion nonuniqueness; requires original node coordinates, absolute reference density and regularization before fusion with2019–2021 velocities." }, "etnaSummitGravity2023": { "doi": "10.3389/feart.2023.1171884", "primaryUrl": "https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1171884/full", "locator": "2D density modelling with IGMAS+, Figure4; terrain correction section", "referenceDensityKgM3": 2400, "scope": "SW–NE summit-area gravity section, down to approximately1200m elevation, about2.1km beneath its highest point. Reference density was selected by gravity/topography correlation, not borehole measurement.", "limits": "Two-dimensional homogeneous formation densities and nonunique gravity inversion; does not define a full-volume Fiandaca material field.", "gridAvailable": false, "dataStatement": "Raw supporting data available from authors; no grid link identified in article.", "articleLicense": "CC BY" }, "priorUncertaintyEvidence": { "doi": "10.3133/ofr20191035", "primaryUrl": "https://www.usgs.gov/publications/petrologic-and-mineral-physics-database-use-us-geological-survey-national-crustal", "scope": "USGS mineral-physics comparison finds empirical velocity-density relations useful on average but substantial lithology-dependent departures. It supplies no Etna-specific uncertainty distribution." } }, "attenuation": { "deGori2005Qp": { "doi": "10.1029/2003JB002875", "primaryUrl": "https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2003JB002875", "locator": "Sections3–5, especially paragraphs7–9,16–24", "units": "Qp dimensionless; t* in seconds", "observationEpoch": "1994–April2001", "frequencyBandHz": [ 1, 30 ], "frequencyCaution": "Most spectral decays were fitted above8–10Hz; frequency-independent Q was justified principally over10–30Hz.", "gridSpacingCentralKm": 3, "depthScopeKm": [ 0, 15 ], "reportedExamplesQp": { "shallowLowQ": [ 40, 50 ], "deepHighQ": [ 200, 250 ] }, "downloadableGridFound": false, "license": "Free-access article; no separately licensed numerical grid located.", "decision": "Structural prior and geological context only for0.2–1Hz; no direct frequency-calibrated Qp input at that band, nor corresponding Qs field." }, "giampiccolo2024": { "doi": "10.1007/s00024-023-03400-0", "primaryUrl": "https://link.springer.com/article/10.1007/s00024-023-03400-0", "primaryRepositoryPdf": "https://www.earth-prints.org/bitstreams/fb2ee3f2-ec76-4c24-be9e-445439832fcb/download", "locator": "Section5.1; Table2 page177 (PDFpage7); Section6; Data availability", "frequencyCentersHz": [ 1.5, 3, 6, 12 ], "definition": { "Qi": "intrinsic quality factor of shear-wave energy", "Qs": "SCATTERING quality factor, not shear-wave Qmu", "Qt": "total effective attenuation", "Qc": "coda attenuation" }, "depthGroupsKm": [ [ 0, 15 ], [ 15, 40 ] ], "table2Columns": [ "frequencyHz", "inverseQi", "inverseQiSigma", "inverseQscattering", "inverseQscatteringSigma", "inverseQt", "inverseQtSigma" ], "table2Shallow": [ [ 1.5, 0.0049, 0.0, 0.0278, 0.0, 0.0327, 0.0 ], [ 3, 0.0048, 0.0002, 0.0145, 0.0018, 0.0193, 0.002 ], [ 6, 0.0035, 0.0008, 0.0043, 0.0011, 0.0078, 0.0019 ], [ 12, 0.0013, 0.0002, 0.0007, 0.0001, 0.002, 0.0003 ] ], "table2Deep": [ [ 1.5, 0.0056, 0.0013, 0.0167, 0.0046, 0.0223, 0.0059 ], [ 3, 0.0047, 0.0019, 0.0057, 0.0024, 0.0104, 0.0043 ], [ 6, 0.0035, 0.0, 0.0028, 0.0, 0.0063, 0.0 ], [ 12, 0.0013, 0.0001, 0.0004, 0.0001, 0.0017, 0.0002 ] ], "uncertaintyCaution": "Zero reported sigma denotes printed grid-search result, not certainty of the Earth model.", "scope": "MLTWA half-space averages, subdivided by depth and four quadrants; not a downloadable3D tomography.", "downloadableGridFound": false, "dataAvailability": "Waveforms in EIDA; additional data from authors.", "articleLicense": "CC BY4.0", "compatibility": "No measured0.2–1Hz field. Effective total loss includes scattering. Putting Qt into intrinsic viscoelastic damping while explicitly modelling heterogeneity can count scattering twice." }, "solverMapping": { "primaryUrl": "https://specfem3d.readthedocs.io/en/latest/03_mesh_generation/", "codeReference": "https://github.com/SPECFEM/specfem3d/blob/7a1c76454396f8dd2f5a67ea524ca372e2c91993/utils/small_utilities/attenuation/conversion_from_Qkappa_Qmu_to_Qp_Qs_from_Dahlen_Tromp_959_960.f90", "requiredInputs": "Qkappa and Qmu; Qmu equals intrinsic shear Qs, Qkappa generally differs from Qp.", "inverseRelation": "1/Qp = a/Qmu + (1-a)/Qkappa, a=4*Vs^2/(3*Vp^2)", "implementationCaution": "SPECFEM constant-Q SLS approximation needs a chosen reference frequency and attenuation band. A power-law effective Q(f) cannot be inserted as one3D constant Q without documenting the approximation and its error.", "preflight": "Check positive admissible inverseQkappa and exact version’s material conventions; do not use scattering Qs as Qmu." } }, "fiandacaPublishedComparison": { "damico2025": { "doi": "10.4401/ag-9152", "primaryUrl": "https://www.annalsofgeophysics.eu/index.php/annals/article/view/9152", "pdfUrl": "https://www.annalsofgeophysics.eu/index.php/annals/article/download/9152/7812/36687", "locator": "Section6, pp9–13; Table1 pp10–11; Figures8–9 pp11–12", "method": "EXSIM stochastic finite fault; not deterministic3D full-wavefield modelling.", "articleLicense": "Creative Commons Attribution; journal page states reuse with attribution.", "parameters": { "MwRange": [ 4.8, 5.0 ], "MwChosen": 4.9, "stressDropRangeMPa": [ 1, 3 ], "stressDropChosenMPa": 2.5, "densityAtSourceKgM3": 1800, "VsAtSourceKms": 1.8, "lengthKm": 7, "widthKm": 2.6, "topDepthKm": 0, "strikeDegrees": 306, "dipDegrees": 88, "rakeDegrees": -158, "subfaultCount": 28, "subfaultDimensionsMeters": [ 1000, 650 ], "pulsingAreaRangePercent": [ 50, 80 ], "pulsingAreaChosenPercent": 50, "slipDistribution": "Random", "window": "Saragoni–Hurt1974", "fmaxRangeHz": [ 5, 15 ], "fmaxChosenHz": 15, "kappaSeconds": null, "kappaNote": "fmax selected instead of kappa; no adopted kappa value supplied.", "QEffective": "Q(f)=45*(f_Hz)^0.77", "QReference": "Giampiccolo2024", "spreadingBreakKm": 40, "spreadingExponents": [ -1, -0.4 ], "amplification": "Haskell propagator, Hirn1991 1D velocities, Christensen–Mooney inferred density", "cornerFrequencyHzReportedFromSarao2023": 2, "inverseCornerFrequencySeconds": 0.5, "processingPassbandHz": null, "processingPassbandNote": "Not explicitly identified in inspected publication. fmax15Hz is a source/roll-off parameter, not an observed-data passband.", "ruptureVelocityPrinted": "0.8/Vs", "ruptureVelocityCaution": "Printed Table1 expression is dimensionally suspect. EXSIM-DMB official parameter format defines vrup/beta; interpreting the paper as vrup/Vs=0.8 is supported by this convention, but remains a documented interpretation rather than the literal printed expression.", "pathDurationNodesEpicentralKm_T90Seconds": [ [ 0, 0 ], [ 7, 3 ], [ 20, 35 ], [ 70, 55 ] ], "pathDurationNodeProvenance": "Visual digitization of Figure8 inset, PDFpage11; source diagram is an empirical epicentral-distance path-duration model, not new station measurements.", "riseTimeFormula": null, "durationCaution": "1/fc0.5s is not a measured total rupture duration, Gaussian halfduration or the observed5–95% shaking duration." }, "stations": { "observationCount": 14, "sourceNetworks": [ "RSN–INGV", "RAN–DPC" ], "soilClassCounts": { "A": 9, "B": 3, "remainingNotSpecifiedHere": 2 }, "namedPublishedStations": [ { "station": "SVN", "PGA_g": 0.56, "locator": "p9,section6.1" }, { "station": "EVRN", "PGA_g": 0.3, "locator": "p9,section6.1" } ], "fullStationTable": null, "fullStationTableStatus": "NOT_PUBLISHED_IN_INSPECTED_ARTICLE: N=14 is given, but a named14-row table is absent. Do not identify the other12 by guesswork or equate an arbitrary ITACA/EIDA selection with the authors’ exact subset.", "durationSelectionRadiusKm": 70, "durationMetric": "T90 from cumulative Arias intensity, ITACA values; source/path separation uses assumptions.", "calibrationCaution": "Authors select parameters by fitting the same14PGA/PGV observations. Those observations are calibration data for their fit, not held-out validation." }, "deGoriCompatibility": "Different epoch,1D crust, source density/Vs assumptions and empirical path loss. Do not transplant these scalar source parameters or crustal amplification onto heterogeneous3D Vp/Vs without controlled sensitivity and avoiding duplicate site effects." }, "additionalPgaReference2023": { "doi": "10.1007/s10518-023-01719-6", "primaryUrl": "https://link.springer.com/article/10.1007/s10518-023-01719-6", "institutionalPdf": "https://www.iris.unict.it/retrieve/66ab8ea0-ce33-4368-914d-2b0950a60cac/An%20eco-sustainable%20innovative%20geotechnical%20technology%20for%20the%20structures%20seismic%20isolation%2C%20investigated%20by%20FEM%20parametric%20analyses.pdf", "locator": "Section4, Table3", "stationRows": [ { "station": "SVN", "PGA_g": 0.559, "epicentralDistanceKm": 4.5, "reportedFrequencyHz": 2.59, "scaleFactor": 1 }, { "station": "EVRN", "PGA_g": 0.301, "epicentralDistanceKm": 5.3, "reportedFrequencyHz": 1.3, "scaleFactor": 1 } ], "scope": "FEM soil/structure study using two actualFiandaca accelerograms plus7scaled records of other earthquakes. Only the first2rows are recordings ofFiandaca2018.", "caution": "Reported scalar PGAs and characteristic frequency are not a waveform matching benchmark; verify component, processing, units and record provenance before numerical comparisons." }, "sarao2023": { "doi": "10.1093/gji/ggad257", "primaryUrl": "https://academic.oup.com/gji/article/234/3/2519/7209153", "locator": "Section2, Table1 event63", "waveformInversionBandsHz": [ [ 0.02, 0.1 ], [ 0.02, 0.05 ] ], "eventSource": { "lat": 37.644, "lon": 15.116, "ML": 4.8, "Mw": 4.9, "centroidDepthKm": 2, "strike": 40, "dip": 88, "rake": -15 }, "caution": "Independent moment tensor solution and low-frequency inversion band; retain as a source alternative, rather than overwrite preferred hypocentre, TDMT tensor or EFMD nodal planes." } }, "exsimSoftware": { "authorPage": "https://www.daveboore.com/software_online.html", "section": "EXSIM_DMB", "latestRevisionShown": "2024-09-25", "distribution": "Author-linkedZIP includes Fortran source, inputs and sample outputs; a separateWindows executable link is also present.", "downloadUrl": null, "downloadUrlStatus": "Exact author-link target not resolved in this research; use inspected author page, not a guessed archive name.", "license": "No specific redistribution license verified in the inspected author page; inspect distribution notice before public redistribution. No package downloaded or run by this research agent.", "role": "Separate stochastic finite-fault branch for FAS/PGA/PGV/response spectra ensembles. Does not generate a geographically resolved deterministic3D subsurface wavefield or validate SPECFEM.", "versionCaution": "August2024 input-parameter semantics changed; old parameter files are incompatible. Freeze source hash, parameter version and random seed." }, "recommendedExperiments": [ { "id": "elastic-reference", "status": "ANALYST_PROPOSAL_NOT_RUN", "materials": "Published De Gori Vp and Vs, Brocher rho prior, attenuation disabled", "purpose": "Reference propagation and numerical checks; no assertion of realistic amplitudes or coda." }, { "id": "rho-sensitivity", "status": "ANALYST_PROPOSAL_NOT_RUN", "materials": "Same Vp/Vs, rho multipliers0.9/1.1 frozen before comparison", "purpose": "Quantify effect of unmeasured density; wider0.8/1.2 tests if needed, not probabilistic bounds." }, { "id": "attenuation-sensitivity", "status": "ANALYST_PROPOSAL_NOT_RUN", "materials": "Separate intrinsic versus effective attenuation hypotheses; reference frequencies documented", "purpose": "Mark extrapolation below1.5Hz. Avoid counting resolved scattering twice. Validate SLS frequency response and velocity reference dispersion." }, { "id": "observed-comparison", "status": "ANALYST_PROPOSAL_NOT_RUN", "materials": "Fixed station epochs, orientations, deconvolution and matched synthetic/observed passband", "purpose": "Reserve independent stations; compare arrival times, waveforms, envelopes, FAS and bandlimited metrics. A published broadband PGA agreement is only a processing sanity check at a compatible station/component." }, { "id": "source-ensemble", "status": "ANALYST_PROPOSAL_NOT_RUN", "materials": "Keep TDMT centroid, preferred hypocentre relocation experiment, Sarao2023 tensor and alternativeSTFs distinct", "purpose": "Finite-fault directivity nearFiandaca requires source geometry and rupture timing; do not confuse1/fc with entire rupture duration." } ] }