Velocity Model

This is the repository for the source code for the New Zealand Velocity Model (NZVM, Ref. https://doi.org/10.1080/00288306.2019.1636830).

As of May 2025, this project is superseded by New Zealand Community Velocity Model (NZCVM) https://github.com/ucgmsim/velocity_modelling NZCVM produces near 100% identical velocity models, and incorporates new data sets and enhancements.

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There are seven general call types which are outlined in this readme.

To clone the code from the github repository:

git clone https://github.com/ucgmsim/Velocity-Model

In order to execute the code:

1. Make a build directory and go into it

mkdir build
cd build

2. Compile - cmake followed by make. Use OpenMP to utilize multiple threads

cmake ../ -DCMAKE_C_FLAGS="-fopenmp" -DCMAKE_CXX_FLAGS="-fopenmp"
make

3Copy NZVM to the root where Data directory is located.

cp NZVM ../

Important: You should always execute "NZVM" at this location.

2. Execute the code using one of the call types:

• GENERATE_VELOCITY_MOD - Generates a velocity model from input parameters
• EXTRACT_VELOCITY_SLICES - Extracts velocity slices from a saved model (Model need to have been previously generated to use this call)
• GENERATE_VELOCITY_SLICES - Generated velocity slices for plotting (slices generated from scratch)
• GENERATE_PROFILE - Generates a velocity profile at a single lat-lon location
• GENERATE_MULTIPLE_PROFILES - Generates profiles for a list of lat-lon locations
• GENERATE_THRESHOLD - Generates a map of Vs30 Vs500, Z1.0 or Z2.5 (on the same coords as the FD 3D model)
• GENERATE_THRESHOLD_USER_INPUT - Generates Vs30, Vs500, Z1.0 or Z2.5 for a user specified list of points

First run

./NZVM 

which creates example input text files (if desired otherwise skip this step)

Then modify the desired parameters and use the text file as an input to NZVM

./NZVM "MyParametersFile.txt"

See the git repo https://github.com/ucgmsim/Velocity-Model-Viz for automated plotting tools.

All five call types and required inputs are explained here.

Call type 1) GENERATE_VELOCITY_MOD

• 1 CALL_TYPE=GENERATE_VELOCITY_MOD
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 ORIGIN_LAT (origin latitude - in decimal format)
• 5 ORIGIN_LON (origin longitude - in decimal format)
• 6 ORIGIN_ROT (model rotation - clockwise is positive)
• 7 EXTENT_X (model extent in the X direction in km)
• 8 EXTENT_Y (model extent in the Y direction in km)
• 9 EXTENT_ZMAX (maximum model extent in the Z direction - positive downwards in km)
• 10 EXTENT_ZMIN (minimum model extent in the Z direction - positive downwards i.e -1 represents +1km above mean sea level)
• 11 EXTENT_Z_SPACING (gridspacing in the Z direction in km)
• 12 EXTENT_LATLON_SPACING (gridspacing in the Y and X direction in km)
• 13 MIN_VS (minimium shear wave velocity to enforce, in km/s - typically 0.5)
• 14 TOPO_TYPE (SQUASHED, BULLDOZED etc)

The output directory must not exist

Call type 2) EXTRACT_VELOCITY_SLICES - All parameters must be set and the output directory must have been generated previously using GENERATE_VELOCITY_MOD call

• 1 CALL_TYPE=EXTRACT_VELOCITY_SLICES
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 ORIGIN_LAT (origin latitude - in decimal format)
• 5 ORIGIN_LON (origin longitude - in decimal format)
• 6 ORIGIN_ROT (model rotation - clockwise is positive)
• 7 EXTENT_X (model extent in the X direction in km)
• 8 EXTENT_Y (model extent in the Y direction in km)
• 9 EXTENT_ZMAX (maximum model extent in the Z direction - positive downwards in km)
• 10 EXTENT_ZMIN (minimum model extent in the Z direction - positive downwards i.e -1 represents +1km above mean sea level)
• 11 EXTENT_Z_SPACING (gridspacing in the Z direction in km)
• 12 EXTENT_LATLON_SPACING (gridspacing in the Y and X direction in km)
• 13 MIN_VS (minimium shear wave velocity to enforce, in km/s - typically 0.5)
• 14 TOPO_TYPE (SQUASHED, BULLDOZED etc)
• 15 EXTRACTED_SLICE_PARAMETERS_TEXTFILE (textfile location withslice parameters)
  • See readme in ExtractedSliceParameters directory for additional information

Call type 3) GENERATE_VELOCITY_SLICES

• 1 CALL_TYPE=GENERATE_VELOCITY_SLICES
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 GENERATED_SLICE_PARAMETERS_TEXTFILE (textfile location with slice parameters)
• 5 TOPO_TYPE (SQUASHED, BULLDOZED etc)

Call type 4) GENERATE_PROFILE - All parameters must be set and the output directory must not exist

• 1 CALL_TYPE=GENERATE_PROFILE
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 PROFILE_LAT (latitude point of profile - in decimal format)
• 5 PROFILE_LON (longitude point of profile - in decimal format)
• 6 PROFILE_ZMIN (minimum depth of profile +ve downwards in km ie. -0.1 corresponds to the
• 7 PROFILE_ZMAX (maximum depth of profile +ve downwards in km)
• 8 EXTENT_Z_SPACING_PROFILE (z spacing of the profile in km) top of the profile at +0.1km above mean sea level)
• 9 PROFILE_MIN_VS (minimium shear wave velocity to enforce, in km/s - typically 0.5, set as 0.0 for no restriction)
• 10 TOPO_TYPE (SQUASHED, BULLDOZED etc)

Call type 5) GENERATE_MULTIPLE_PROFILES - Two different types: constant spacing, and variable spacing profile generation (the output directory must not exist)

• 1 CALL_TYPE=GENERATE_MULTIPLE_PROFILES
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 OUTPUT_TYPE (Specify the toe of file output required - 1D_SITE_RESPONSE or STANDARD)
• 5 PROFILE_MIN_VS (minimium shear wave velocity to enforce, in km/s - typically 0.5, set as 0.0 for no restriction)
• 6 TOPO_TYPE (SQUASHED, BULLDOZED etc)
• 7 COORDINATES_TEXTFILE (textfile location with coordinates to generate profiles at)
• 8 SPACING_TYPE (Set as CONSTANT, or VARIABLE)
• Optional inputs
• if SPACING_TYPE=CONSTANT, then set:
• 9 PROFILE_ZMIN (minimum depth of profile +ve downwards in km ie. -0.1 corresponds to the
• 10 PROFILE_ZMAX (maximum depth of profile +ve downwards in km)
• 11 SPACING_PROFILE (z spacing of the profile in km)
• if SPACING_TYPE=VARIABLE, then set:
• 12 PROFILE_DEPTHS_TEXTFILE (textfile location with vector of depths to prescribe velocities to)

Call type 6) GENERATE_THRESHOLD

Extracts Vs30 Vs500 Z1.0 Z2.5 for the same coords as the FD grid

• 1 CALL_TYPE=GENERATE_THRESHOLD
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 ORIGIN_LAT (origin latitude - in decimal format)
• 5 ORIGIN_LON (origin longitude - in decimal format)
• 6 ORIGIN_ROT (model rotation - clockwise is positive)
• 7 EXTENT_X (model extent in the X direction in km)
• 8 EXTENT_Y (model extent in the Y direction in km)
• 9 EXTENT_LATLON_SPACING (gridspacing in the Y and X direction in km)
• 10 VS_TYPE (set as Vs30 Vs500 Z1.0 Z2.5)

Call type 7) GENERATE_THRESHOLD_USER_INPUT

Extracts Vs30 Vs500 Z1.0 Z2.5 for a user specified list of points

• 1 CALL_TYPE=GENERATE_THRESHOLD_USER_INPUT
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 COORDINATES_TEXT_FILE (text file name containing gridpoints to presribe velocities at)
• 5 VS_TYPE (set as Vs30 Vs500 Z1.0 Z2.5)

Call type 8) GENERATE_VELOCITIES_ON_GRID

• 1 CALL_TYPE=GENERATE_VELOCITIES_ON_GRID
• 2 MODEL_VERSION (model version - select from list of model versions at bottom of readme)
• 3 OUTPUT_DIR (directory to save outputs to)
• 4 TOPO_TYPE (SQUASHED, BULLDOZED etc)
• 5 MIN_VS (minimium shear wave velocity to enforce, in km/s - typically 0.5)
• 6 COORDINATES_TEXT_FILE (text file name containing gridpoints to presribe velocities at)

Execute one of these call types and open the output directory to view saved outputs.

To add a new basin model to the NZVM follow the instructions in src/Addition_of_new_basins_readme.md

List of TOPO_TYPES

Unshifted representations:

• TRUE
• BULLDOZED - Cuts off all gridpoints above Mean Sea Level (0km)

Shifted representations: Note that no gridpoint with a value above Mean Sea Level (MSL) (0km) will have velocities prescribed to it.

• SQUASHED - Pushes the ground surface (DEM) to zero meteres, all values are then relative to this.
• SQUASHED_TAPERED - Compacts the region between the DEM and MSL into the region between MSL and -1.0xZ(DEM)

Summary of velocity model version numbers

• v1.01 1D velocity model

  • 1D model version (Cant. 1D velocity model)

• v1.02 1D velocity model

  • 1D model version (Cant. 1D velocity model v2)

• v1.11 Eberhart-Phillips Tomography

  • (Unpublished updated Canterbury version)

• v1.21 Tomography below basement, 1D above

  • 1D model version (Cant. 1D velocity model)
  • Basement version (BasementPoints_35_v8p9_1000m.txt)

• v1.22 Tomography below basement, 1D above

  • 1D model version (Cant. 1D velocity model v2)
  • Basement version (BasementPoints_35_v8p9_1000m.txt)

• v1.31 Tomography below basement, constant velocity Paleogene layer, 1D Above

  • 1D model version (Cant. 1D velocity model)
  • Basement version (BasementPoints_35_v8p9_1000m.txt)
  • Paleogene version (PaleogenePoints_35_v8p9_1000m.txt)
  • Paleogene - Vp=2.7 , Vs=1.1511 , Rho=2.151

• v1.41 Tomography below basement, constant velocity Paleogene & Miocene layers, 1D Above

  • 1D model version (Cant. 1D velocity model)
  • Basement version (BasementPoints_35_v8p9_1000m.txt)
  • Paleogene version (PaleogenePoints_35_v8p9_1000m.txt)
  • Miocene version (MiocenePoints_35_v8p9_1000m.txt)
  • Paleogene - Vp=2.7 , Vs=1.1511 , Rho=2.151
  • Miocene - Vp=2.5, Vs=0.98355, Rho=2.9031

• v1.51 Tomography below basement, constant velocity Paleogene & Miocene layers, 1D Above, BPV Basin

  • 1D model version (Cant. 1D velocity model)
  • Basement version (BasementPoints_35_v8p9_1000m.txt)
  • Paleogene version (PaleogenePoints_35_v8p9_1000m.txt)
  • Miocene version (MiocenePoints_35_v8p9_1000m.txt)
  • BPV top version (BPPoints_41_v1p13_1000m.txt)
  • Paleogene - Vp=2.7 , Vs=1.1511 , Rho=2.151
  • Miocene - Vp=2.5, Vs=0.98355, Rho=2.9031
  • BPV - Vp=4.0, Vs=2.2818, Rho= 2.393

• v1.61 Tomography below basement, constant velocity Paleogene, Miocene & Pliocene layers, 1D Above, BPV Basin

  • 1D model version (Cant. 1D velocity model)
  • Basement version (BasementPoints_35_v8p9_1000m.txt)
  • Paleogene version (PaleogenePoints_35_v8p9_1000m.txt)
  • Miocene version (MiocenePoints_35_v8p9_1000m.txt)
  • Pliocene version (PliocenePoints_35_v8p9_1000m.txt)
  • BPV top version (BPPoints_41_v1p13_1000m.txt)
  • Paleogene - Vp=2.7 , Vs=1.1511 , Rho=2.151
  • Miocene - Vp=2.5, Vs=0.98355, Rho=2.9031
  • Pliocene - Vp=2.0, Vs=0.6086, Rho = 1.905
  • BPV - Vp=4.0, Vs=2.2818, Rho= 2.393

• v1.62 Same as v1.61 with different parameters for the BPV

  • BPV - Vp=3.6, Vs=1.9428, Rho= 2.334

• v1.63 Same as v1.61 with weathering function for the top 100m of the BPV

  • BPV at 0m - Vp=3.2, Vs=1.59, Rho= 2.265
  • BPV below 100m - Vp=4.0, Vs=2.2818, Rho= 2.393
  • Linear relationship between 0 and 100m depth

• v1.64 Same as v1.63 with updated 1D velocity model

  • 1D model version (Cant1D_v2.fd_modfile)

• v1.65 Same as v1.64 with updated 1D velocity model to ensure Vs_1dmax < Vs_pliocene

  • 1D model version (Cant1D_v2_Pliocene_Enforced.fd_modfile)

• v1.66 Same as v1.65 with updated pliocene layer model

• v1.67 Same as v1.66 with ELY (2010) taper implemented in non-basin regions. New NZ-Wide HD DEM. Updated weathering in BPV region.

  • Weathering in BPV modified from ELY (2010), using Vs_BPV(top)=700m/s @ z=0, Vs_BPV(top)=1500m/s @ z=1000m (linearly varying between)

• v2.01 Added 5 new South Island Basins (Kaikoura, Cheviot, Hanmer, Marlborough, NorthCanterbury) and offshore tapering

• v2.02 Updated Wellington basin model

• v2.03 added WaikatoHauraki_v19p7 basin model, offshore generic basin model added

• v2.03_m10 with m10 perturbaton from F3DT

• v2.03_m15 with m15 perturbaton from F3DT

• v2.04 added USER20 basins

• v2.05 Updated 2020 tomography model

• v2.05_m12 with m12 perturbaton from F3DT (2020 tomography model)

• v2.06 Added Takaka / Collingwood Basins / Springs Junction & Karamea

• v2.07 Added Hawkes Bay / Napier / Wellington Regional basins and Updated the Wellington Basin to Matt Hill's version / Wairarapa / S. Hawkes Bay / Gisborne / Motu

• v2.08 Replaced tomography model with the combination of Chow's North Island tomography model and EP2020 with/without basins (basins from v2.07)

Summary of Korean velocity model (KVM) version numbers

• KVM_20p6 - 1D VM

• KVM_20p12 - 3D VM Based on "Crustal structure beneath the southern Korean Peninsula from local earthquakes" Kim et al (2017), Vs and Rho derived from Brocher (2005) relationships

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How to build docker image

We will be adding NZVM binary into a minimum base image. This containerized NZVM binary is used to test the NZCVM.

If you haven't, build a NZVM first.

mkdir build
cd build
cmake ../ -DCMAKE_C_FLAGS="-fopenmp" -DCMAKE_CXX_FLAGS="-fopenmp"
make

Create a Dockerfile

FROM gcc:latest

# Copy the pre-built binary into the Docker image
COPY NZVM /nzvm/NZVM

# Set the working directory
WORKDIR /nzvm

In the directory where NZVM and Dockerfile are located, build the docker image. Our Docker Hub handler is earthquakesuc

docker build -t earthquakesuc/nzvm .

or

docker build --no-cache -t earthquakesuc/nzvm .

(Optional) Tag the image

docker tag earthquakesuc/nzvm quathquakesuc/nzvm:v1.0

Push to Docker Hub. First make sure you're logged into Docker Hub

docker login

Then push the image

docker push earthquakesuc/nzvm

Or push a specific tag

docker push earthquakesuc/nzvm:v1.0