Seismic reflection horizons (in depth), P-wave velocities and velocity-derived porosities, all from Seismic Line PEG09-23, southern Hikurangi Margin, New Zealand

This contribution contains interpreted data generated from a seismic reflection profile (Line PEG09-23) located at the southern Hikurangi Margin of New Zealand. The seismic reflection data themselves and corresponding seismic velocities are published elsewhere and can be downloaded from the Mendeley cloud-based communal repository (Crutchley and Klaeschen, 2020). 1) Interpreted seismic depth horizons picked on the seismic section. "Depth-Horizons_GeoQuest-CARD-IMAGE-7.txt" The seismic horizons were picked in depth using “The Kingdom Suite” interpretation software. The picks were informed by comparison to seismic interpretations carried out on a two-way-time version of Line PEG09-23 (Barnes et al., 2026). The data products were generated during the year 2025 for the purpose of investigating sediment compaction in the subduction trench of the southern Hikurangi Margin. The interpreted seismic horizons are provided in a standard output format from The Kingdom Suite software, “GeoQuest Card Image 7”, which is a fixed-column ASCII format file. These files can be directly read into The Kingdom Suite, but can also be manipulated to be read by other means, like with a simple text editor, MS Excel, or python, for example. The following information is useful for reading the file: Each horizon begins with two header lines, like the following:PROFILE 0923-R4A_z TYPE 1 5 SNAPPING PARAMETERS 1 20 2The text after “PROFILE”, i.e. “0923-R4A_z” is the designated name of the horizon to follow. In this case the prefix “0923” refers to the seismic line “PEG09-23”, on which this horizon “R4A” was picked. All horizons in this file begin with “0923-”, then have the horizon name matching the nomenclature defined by Barnes et al. (2026) (e.g. “R4A”), followed by a suffix “_z” to designate that they are in depth (z). After the two header lines, there are nine fixed-width columns that represent the following: Column 1: X coordinate (metres, EPSG:32760 - WGS 84 / UTM zone 60S).Column 2: Y coordinate (metres, EPSG:32760 - WGS 84 / UTM zone 60S).Column 3: Depth (m) below sea-level of the horizon pick.Column 4: Trace ID along the seismic section.Column 5: Repeat of Column 3.Column 6: Integer version of Column 4.Column 7: Seismic Amplitude at the horizon pick.Column 8: Line type (“2” refers to 2D data).Column 9: Seismic Line name. After all tabulated data for a given horizon, there is an end of data entry on a new line, e.g. “EOD 0923-R4A_z”, before the two header lines for the next horizon in the file. 2) P-wave velocities extracted within particular intervals and velocity-derived porosities from intervals. "PEG0923-Depth-Intervals-Vp-phi.xlsx" Excel spreadsheet. We defined four seismic intervals bound by particular horizons in the file provided in (1). Details are: Interval 1: Between horizons SB (seabed, top horizon) and R3 (bottom horizon).Interval 2: Between horizons R3 (top horizon) and RX (bottom horizon)Interval 3: Between horizons RX (top horizon) and R5 (bottom horizon)Interval 4: Between horizons BSU6 (top horizon) and R6-BSU7 (bottom horizon) The horizon RX is newly defined here, while the other horizons are after Barnes et al. (2026). The following information is relevant to the file "PEG0923-Depth-Intervals-Vp-phi.xlsx": Sheet 1 ("Intervals_Vp") Column A: Interval IdentifierColumn B: Trace ID (Integer trace number from seismic line)Column C: Depth at the top of the interval in metres (e.g., for Interval 1, this would be the seabed depth) at the given Trace IDColumn D: Depth at the bottom of the interval in metres (e.g., for Interval 1, this would be the depth of Horizon R3) at the given Trace IDColumn E: Thickness of the interval (metres) at the given Trace IDColumn F: Depth below seafloor of the midpoint of the interval (metres) at the given Trace IDColumn G: Mean P-wave velocity in the interval (m/s) at the given Trace IDColumn H: X coordinate of the given Trace ID (UTM Zone 60S, metres)Column I: Y coordinate of the given Trace ID (UTM Zone 60S, metres) Sheet 2 ("Intervals_phi") This sheet has velocity-derived porosities from two selected intervals (Interval 3 and Interval 4): Column A: Interval IDColumn B: Trace IDColumn C: X coordinate of the given Trace ID (UTM Zone 60S, metres)Column D: Y coordinate of the given Trace ID (UTM Zone 60S, metres)Column E: Mean P-wave velocity in the interval (m/s) at the given Trace IDColumn F: Thickness of the interval at the given Trace IDColumn G: Depth below seafloor of the midpoint of the interval (metres) at the given Trace IDColumn H: Modelled phi0 (fractional seafloor porosity) for normal consolidation (Athy-type curve) for this intervalColumn I: Modelled beta value for normal consolidation (Athy-type curve) for this intervalColumn J: Vp-derived fractional porosity for this interval at the given Trace IDColumn K: Athy-type (normal consolidation) fractional porosity for this interval at the given Trace ID