Dear Colleague,

The National Science Foundation has recently funded an initiative to create a 3D Reference Earth Model with broad community input and oversight. The first phase of this project involves compilation of seismic datasets contributed by the community that will be used in model construction and validation. This is a call for contributions of long-period seismic datasets made on behalf of the 3D Reference Earth Model Project and the Reference Seismic Dataset Working Group. Three types of datasets are requested:

  • Surface waves: Phase and group velocity measurements at periods longer than 20 seconds;
  • Body waves: Absolute and differential travel-time measurements;
  • Free Oscillations: Center frequency, splitting, and attenuation measurements.

All contributed datasets will be cross-validated and reconciled for baseline or reference shifts, when necessary, and combined into a reference seismic dataset. For contributed datasets to be both cross-validated and utilizable by the broader community, they must be accompanied by all relevant metadata outlined below:

  1. Surface waves:
    1. Orbit (R1/G1/R2/G2)
    2. Overtone number (0-Fundamentals, 1-First Overtone)
    3. Source/receiver locations in geographic coordinates
    4. Measurement technique:
      1. Reference model (PREM/other)
      2. Focal mechanisms employed (Global CMT/other)
      3. Type of synthetics used (Normal modes/SPECFEM/other)
      4. Filtering (passbands-cutoff and corner frequencies, type of filter)
      5. Method for calculating error estimates
    5. Values and procedure for corrections applied:
      1. Ellipticity corrections (if any).
      2. Azimuthal anisotropy corrections (if any).
      3. Crustal corrections (if any).
  2. Body Waves:
    1. Source/receiver locations in geographic coordinates
    2. Dominant period
    3. Component (Vertical/Transverse)
    4. Measurement technique:
      1. Reference model (PREM/other)
      2. Type of synthetics used (Normal modes/SPECFEM/Other)
      3. Focal mechanisms employed (Global CMT/other)
      4. Filtering (passbands-cutoff and corner frequencies, type of filter)
      5. Method for calculating error estimates
    5. Values and procedure for corrections applied:
      1. Ellipticity corrections (if any).
      2. Dispersion (t* ) correction (if any)
      3. Crustal corrections (if any).
  3. Free Oscillations:
    1. Normalization for spherical harmonics
    2. Measurement technique:
      1. Type of measurement (Iterative Spectral Fitting/Matrix autocorrelation/Singlet stripping/Other)
      2. Reference Model
      3. Number of Q cycles used
      4. Filtering (passbands-cutoff and corner frequencies, type of filter)
      5. Focal mechanisms employed (Global CMT/other)
    3. Values and procedure for corrections applied:
      1. Ellipticity and rotation corrections.
      2. Tidal corrections (if any).

All metadata should be specified in a short note accompanying the contribution or be retrievable from the manuscripts cited therein. The contribution may be sent to the Reference Seismic Dataset Working Group at  either as an attachment or an FTP link to an external server. All contributions will be acknowledged on the web platform we will build for the distribution of model and data products from the 3D Reference Earth Model Project.

Please let us know if you have any questions or concerns.

Yours sincerely,

Raj Moulik
Ved Lekic
Barbara Romanowicz
Adam Dziewonski

Reference Seismic Dataset Working Group
[Arwen Deuss, Eric Debayle, Göran Ekström, Sergei Lebedev, Guy Masters, Jeroen Ritsema, Karin Sigloch]