Data Services Products: EMC-CAP22 An absolute P-wavespeed tomographic model with focus on North America

Summary

CAP22 is an absolute P-wave speed tomographic model with focus on North America, specifically Canadian and Alaskan mantle structure, provided with and without crustal correction.

Description

Name CAP22
Title An absolute P-wave speed tomographic model with focus on North America
Type 3-D Tomography Earth Model
Sub Type Absolute P-wave speed
Year 2022
Data Revision revision history)
 
Short Description   CAP22_NACr14_MOD is an adaptively parameterized, global absolute P-wave tomographic model following the methodology of Li et al., (2008). The crustal correction implemented in this model is described in the manuscript and supplementary material. ak135 (Kennett et al., 1995) is used as the global reference model. New data has been added in Canada and Alaska, so we provide only the North American component of the model. While the adaptively parameterized grids at upper mantle depths can be found in the supplementary material of the manuscript, here we provide the model sampled at 0.25×0.25 degrees and 50km depth to facilitate smooth plotting. The 3D grid contains the columns: latitude (deg), longitude (deg), depth (km), dVp (percentage relative to ak135), vp (absolute vp in km/s).
CAP22_MOD is an identical tomographic model to that above but no crustal correction is implemented.

Also available is a resolution/illumination mask for the upper part of the model (CAP22_MASK_5deg). Regions with less than adequate resolution in CAP22 are determined following the methodology of Burdick et al.,. Regions where the mask is on (i.e. equal to 1) are regions of low confidence or poor resolution. Regions where the mask is off (i.e. equal to 0) are regions of high confidence or good resolution. Values between these two extremes result from sampling the adaptively parameterized grid at 0.25×0.25 degree intervals to facilitate smooth plotting. Irregular spatial plotting grids result from coordinate rotations applied to the data (see main manuscript) but can be easily resampled for plotting. The 3D grid contains the columns: latitude (deg), longitude (deg), depth (km), mask on (1/0).
 
Authors: A. Boyce: University of Cambridge, Department of Earth Science, Bullard Laboratories, Madingley Road, Cambridge, UK.
M. V. Liddell: Centre de recherche Geotop, Université du Québec à Montréal, QC, Canada.
S. Pugh: University of Cambridge, Department of Earth Science, Bullard Laboratories, Madingley Road, Cambridge, UK.
J. Brown: University of Cambridge, Department of Earth Science, Bullard Laboratories, Madingley Road, Cambridge, UK.
E. McMurchie: University of Cambridge, Department of Earth Science, Bullard Laboratories, Madingley Road, Cambridge, UK.
A. Parsons: University of Cambridge, Department of Earth Science, Bullard Laboratories, Madingley Road, Cambridge, UK.
C. Estève: Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria.
S. Burdick: Wayne State University, Geology Department, Detroit, MI, USA.
F. A. Darbyshire: Centre de recherche Geotop, Université du Québec à Montréal, QC, Canada.
S. Cottaar: University of Cambridge, Department of Earth Science, Bullard Laboratories, Madingley Road, Cambridge, UK.
I. D. Bastow: Department of Earth Science and Engineering, Royal School of Mines, Prince Consort Road, Imperial College London, London, UK.
A. J. Schaeffer: Geological Survey of Canada Pacific Division, Sidney, BC, Canada.
P. Audet: University of Ottawa, Department of Earth and Environmental Sciences, Ottawa, ON, Canada.
D. L. Schutt: Colorado State University, Department of Geosciences and Warner College of Natural Resources, Fort Collins, CO, USA.
R. C. Aster: Colorado State University, Department of Geosciences and Warner College of Natural Resources, Fort Collins, CO, USA.
 
Reference Model ak135
 
Model Download The original model files CAP22_Original_distributable_model.tar.gz

The above models in netCDF 3 Classic format.

CAP22-NACr14-MOD-3D.r0.0.nc (see metadata)

CAP22-MOD-3D.r0.0.nc (see metadata)

CAP22-MASK-5deg-3D.r0.0.nc (see metadata)
 
Depth Coverage 50-2850km
 
Area North America, specifically Canadian and Alaskan mantle structure
 
Data Set Description Our global dataset of absolute arrival-time picks includes P, Pn, Pg, pP, PKP, PKiKP and PKIKP phases from the “EHB” database (Engdahl et al., 1998) spanning the period 1964-2004 (Li et al., 2008a) and USArray Transportable Array (TA) data recorded from 2004-2020. We improve resolution in Canada and Alaska by incorporating numerous smaller regional seismic networks. These total 202,719 P arrivals from 8319 earthquakes recorded in North America at 1,562 stations over the period 2002-2020. Further details on analysis of these datasets can be found in the main manuscript.

Included in the above original model files: The file CAP22_phase_SUMMARY.txt contains the details of direct P-phase absolute arrival-time picks derived from networks in Canada and Alaska. The file CAP22_event_SUMMARY.txt contains the details of corresponding earthquakes (See README for more details). The raw data files, processed data, inversion software package and plotting codes are available at https://doi.org/10.5281/zenodo.7510591.
 
 

CAP22
CAP22 North American tomographic model at 150km depth, plotted as deviation from ak135 (dVp = +/- 1.5%) over topographic shading. Grey areas are unresolved according to recovery of 5° checkerboard anomalies (following Burdick et al., 2014; See Supplementary Material). AF: Appalachian Front, AL-S: Alaskan slab, AP: Appalachian Province, CDF: Cordilleran Deformation Front, EXP: Explorer plate, GDA: Gorda plate, GF: Grenville Front, GP: Grenville Province, GSLsz: Great Slave Lake shear zone, JDF: Juan de Fuca plate, LLTZ: Liard Line Transfer Zone, MC: Possible location of Mackenzie Craton, QCF: Queen Charlotte Fault, RMT: Rocky Mountain Trench, SLA: Slave craton, STZ: Snowbird tectonic zone VI: Vancouver Island. Other structural boundaries as in main manuscript. Please see the referenced manuscript for further information.

Citations and DOIs

To cite the original work behind this Earth model:

  • Boyce, A., et al. (2023). A new P-wave tomographic model (CAP22) for North America: Implications for the subduction and cratonic metasomatic modification history of western Canada and Alaska. Journal of Geophysical Research: Solid Earth, 128, e2022JB025745. https://doi.org/10.1029/2022JB025745

To cite IRIS DMC Data Products effort:

  • Trabant, C., A. R. Hutko, M. Bahavar, R. Karstens, T. Ahern, and R. Aster (2012), Data Products at the IRIS DMC: Stepping Stones for Research and Other Applications, Seismological Research Letters, 83(5), 846–854, https://doi.org/10.1785/0220120032.

DOI for this EMC webpage: https://doi.org/10.17611/dp/emc.2023.cap22.1


References

  • Engdahl, et al., (1998). Global teleseismic earthquake relocation with improved travel times and procedures for depth determination. Bull. Seismol. Soc. Am. 88, 722–743.

Credits

  • Model was provided by Alistair Boyce.

Revision History

uploaded January 10, 20223.

Timeline

2023-03-07
online

Categories

15:38:25 v.eb79165e