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  Mt. Etna Ground Motion Dataset — README
  Parametric tables of intensity measures and associated metadata
  University of Genoa (UniGe) / INGV
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DATASET OVERVIEW
----------------
This dataset contains parametric tables of ground-motion intensity measures
for volcano-tectonic earthquakes recorded in the Mt. Etna region (Sicily,
Italy). It is organized in three sets of files:

  - FLAT_PgaPgv.csv         : one file, peak ground motion parameters (PGA, PGV)
  - FAS/FAS_<freq>.csv      : 98 files, Fourier Amplitude Spectra ordinates
  - SA/SA_<freq>.csv        : 98 files, 5%-damped acceleration response spectra ordinates

In FAS and SA files, each file corresponds to a specific frequency [Hz],
indicated in the filename (e.g., FAS_001.00.csv contains ordinates at 1.00 Hz).

Ground-motion values are reported for three components: vertical (Z),
north-south (NS), and east-west (EW).


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  COLUMN DESCRIPTIONS — FLAT_PgaPgv.csv
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--- EVENT METADATA ---

Id_UniGe      Unique recording identifier assigned by UniGe. Format: origin time
              of the event (YYMMDDHHmmss) as recorded in the ONT catalog.

Id_INGV       Event identifier in the INGV earthquake catalog.

Ml_ONT        Local magnitude from the Osservatorio Nazionale Terremoti
              (ONT) catalog.

EvLat_ONT     Event latitude [decimal degrees, WGS84] from the ONT catalog.

EvLon_ONT     Event longitude [decimal degrees, WGS84] from the ONT catalog.

EvtDpt_ONT    Event focal depth [km] from the ONT catalog.

Ml_OE         Local magnitude from the Osservatorio Etneo (OE) catalog.

EvLat_OE      Event latitude [decimal degrees, WGS84] from the OE catalog.

EvLon_OE      Event longitude [decimal degrees, WGS84] from the OE catalog.

EvtDpt_OE     Event focal depth [km] from the OE catalog.

--- STATION AND RECORDING METADATA ---

FDSN          Station identifier in FDSN format: Network.Station.Location.Channel
              (e.g., IV.ESLN..HH).

Cmp           Seismometric channel code.

StLat         Station latitude [decimal degrees, WGS84].

StLon         Station longitude [decimal degrees, WGS84].

StElev        Station elevation [m above sea level].

Depi_ONT      Epicentral distance [km], computed from ONT event location.

Dipo_ONT      Hypocentral distance [km], computed from ONT event location.

Az_ONT        Source-to-station azimuth [degrees], computed from ONT location.

Baz_ONT       Station-to-source back-azimuth [degrees], computed from ONT location.

Depi_OE       Epicentral distance [km], computed from OE event location.

Dipo_OE       Hypocentral distance [km], computed from OE event location.

Az_OE         Source-to-station azimuth [degrees], computed from OE location.

Baz_OE        Station-to-source back-azimuth [degrees], computed from OE location.

--- GROUND-MOTION PARAMETERS ---

PGA_Z_S       Peak Ground Acceleration, vertical component [cm/s²].

PGA_NS_S      Peak Ground Acceleration, north-south component [cm/s²].

PGA_EW_S      Peak Ground Acceleration, east-west component [cm/s²].

flZ           Low-cut (high-pass) corner frequency of the Butterworth band-pass
              filter applied to the vertical component [Hz].

fhZ           High-cut (low-pass) corner frequency of the Butterworth band-pass
              filter applied to the vertical component [Hz].

flNS          Low-cut corner frequency of the filter applied to the NS component [Hz].

fhNS          High-cut corner frequency of the filter applied to the NS component [Hz].

flEW          Low-cut corner frequency of the filter applied to the EW component [Hz].

fhEW          High-cut corner frequency of the filter applied to the EW component [Hz].

PGV_Z_S       Peak Ground Velocity, vertical component [cm/s].

PGV_NS_S      Peak Ground Velocity, north-south component [cm/s].

PGV_EW_S      Peak Ground Velocity, east-west component [cm/s].

--- SITE METADATA ---

vs30          VS,30 [m/s] derived from geophysical measurements only.

ec8           EC8 site class derived from geophysical measurements only.

vs30_fin      Final VS,30 [m/s] used in the dataset, derived from geophysical
              measurements where available, supplemented by proxy-based estimates
              (topographic slope correlation).

ec8_fin       Final EC8 site class used in the dataset, derived from geophysical
              measurements where available, supplemented by proxy-based estimates.

topo_class    NTC topographic category.

f0_N_Hz       Fundamental resonance frequency f0 [Hz] estimated from ambient
              noise HVSR (N-HVSR).

A0_N          Peak amplitude A(f0) of the N-HVSR curve at f0.

TypeCurve_N   Morphological classification of the N-HVSR curve shape.

f0_S_Hz       Fundamental resonance frequency f0 [Hz] estimated from S-wave
              HVSR (S-HVSR).

A0_S          Peak amplitude A(f0) of the S-HVSR curve at f0.

TypeCurve_S   Morphological classification of the S-HVSR curve shape.


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  COLUMN DESCRIPTIONS — FAS/FAS_<freq>.csv
================================================================================

Columns shared with FLAT_PgaPgv.csv (same definitions as above):
  Id_UniGe, Ml_ONT, FDSN, Cmp, EvLat_ONT, EvLon_ONT, EvtDpt_ONT,
  StLat, StLon, StElev, Depi_ONT, Dipo_ONT, Az_ONT, Baz_ONT,
  Ml_OE, EvLat_OE, EvLon_OE, EvtDpt_OE, Depi_OE, Dipo_OE, Az_OE, Baz_OE,
  vs30, ec8, vs30_fin, ec8_fin, topo_class,
  f0_N_Hz, A0_N, TypeCurve_N, f0_S_Hz, A0_S, TypeCurve_S.

Additional columns specific to FAS files:

MSta          Local magnitude (ML) estimate at each station.

FAS_Z         Fourier Amplitude Spectrum ordinate, vertical component [cm/s].

FAS_NS        Fourier Amplitude Spectrum ordinate, north-south component [cm/s].

FAS_EW        Fourier Amplitude Spectrum ordinate, east-west component [cm/s].

LenZ          Duration [s] of the S-wave time window used for spectral computation,
              vertical component.

LenNS         Duration [s] of the S-wave time window used for spectral computation,
              north-south component.

LenEW         Duration [s] of the S-wave time window used for spectral computation,
              east-west component.

Freq          Frequency [Hz] of the spectral ordinates reported in the file.


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  COLUMN DESCRIPTIONS — SA/SA_<freq>.csv
================================================================================

Columns shared with FLAT_PgaPgv.csv (same definitions as above):
  Id_UniGe, Ml_ONT, FDSN, Cmp, EvLat_ONT, EvLon_ONT, EvtDpt_ONT,
  StLat, StLon, StElev, Depi_ONT, Dipo_ONT, Az_ONT, Baz_ONT,
  Ml_OE, EvLat_OE, EvLon_OE, EvtDpt_OE, Depi_OE, Dipo_OE, Az_OE, Baz_OE,
  vs30, ec8, vs30_fin, ec8_fin, topo_class,
  f0_N_Hz, A0_N, TypeCurve_N, f0_S_Hz, A0_S, TypeCurve_S.

Additional columns specific to SA files:

MSta          Local magnitude (ML) estimate at each station.

SA_Z          5%-damped pseudo-spectral acceleration ordinate, vertical component
              [cm/s²].

SA_NS         5%-damped pseudo-spectral acceleration ordinate, north-south component
              [cm/s²].

SA_EW         5%-damped pseudo-spectral acceleration ordinate, east-west component
              [cm/s²].

LenZ          Duration [s] of the S-wave time window used for spectral computation,
              vertical component.

LenNS         Duration [s] of the S-wave time window used for spectral computation,
              north-south component.

LenEW         Duration [s] of the S-wave time window used for spectral computation,
              east-west component.

Freq          Frequency [Hz] of the spectral ordinates reported in the file.


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  NOTES
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1. The dataset includes recordings from 200 volcano-tectonic earthquakes
   (ML 3.0–4.8) that occurred in the Mt. Etna region between February 2008
   and July 2023.

2. Event locations and magnitudes are provided from two independent catalogs:
   - ONT: Osservatorio Nazionale Terremoti (INGV)
   - OE:  Osservatorio Etneo (INGV)

3. Ground-motion parameters are reported in physical units:
   - PGA and SA ordinates: cm/s²
   - PGV ordinates: cm/s
   - FAS ordinates: cm/s

4. Spectral ordinates (FAS and SA) are computed at 98 logarithmically spaced
   frequencies in the range 0.05–47.20 Hz.

5. FAS records with signal-to-noise ratio (SNR) < 2.5 at a given frequency
   are excluded from the corresponding FAS file, resulting in a variable
   number of records across frequencies.

6. Site classification follows the EC8 (Eurocode 8) scheme and is provided
   at two levels: based on geophysical measurements alone (vs30, ec8) and
   as a final assignment incorporating proxy-based estimates (vs30_fin, ec8_fin).

7. HVSR parameters (f0, A0, TypeCurve) are available only for a subset of 40
   stations located in the Mt. Etna area.

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  CITATION
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When using this dataset, please cite:

Tarchini, G., G. Brunelli, G. Lanzano, G. Tusa et al. (2026).
Mt_Etna_flatfile: Parametric table of the intensity measures and associated
metadata of waveforms of the earthquake (ML >= 3) occurred in Mount Etna
region in the time interval 2008-2023. [Data set].
Istituto Nazionale di Geofisica e Vulcanologia (INGV).
https://doi.org/10.13127/volcanic_gm_data/mt_etna.1.0

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