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What is DNA? The DNA models are a series of 3D tomographic velocity models of the North American continent. The models have been developed through the collaboration of several groups and have a home at UC Berkeley. They make use of the Earthscope geophysical datasets as well as the permanent regional geophysical networks and short-term deployments. As the USArray rolls across the continent (current station locations) the additional data are incorporated into new versions of the models. At the same time, additional geophysical constraints are used and integrated into a simultaneous inversion of the 3D roots of the continent.

The purpose of this site is to make the models easily available to the broad community to download and slice. The models have been peer-reviewed and published. Detailed information about their generation and interpretation are available in the journal manuscripts accompanying each model. If you have questions, or would like to be notified when new models are posted, please contact Richard Allen.


The DNA models...

DNA13-P, -SV, -SH, -SVjoint

  • The DNA13 model contains four estimates of the relative seismic wave-speed (1 P and 3 S) in the continuous US upper mantle.
  • The P, SH, and SV components utilize finite-frequency kernels and relative first arrival times for a set of body-wave only models.
  • The SV-Joint component utilizes the SV component relative arrival times, teleseismically determined phase velocities, and ambient noise derived phase velocities in a single inversion.
  • The Wyoming Province is imaged as thicker lithosphere than the surrounding continent, but with a low velocity zone due to the Yellowstone Plume. This thick lithosphere is coincident with the dipping high velocity body imaged by Yuan et al. with the CD-ROM array, but extends further eastward than the earlier experiment could resolve.
  • The Llano province in central Texas is separated from the Laurentia Craton by the Southern Oklahoma Aulacogen which exhibits thin lithosphere under the basin. A high velocity body imaged under the Llano Province dips to the northeast and strikes along the Grenville Front suggesting it originated during the Grenville Orogeny at ~1.1Ga.
  • The mantle structure through the transition zone displays markedly high velocity anomalies suggesting a tenuous subduction path for the Farallon slab.
  • Porritt, Allen and Pollitz EPSL, 2014
  • DNA13 information, download and slice


Map and cross-section highlighting the deep slab under the eastern US. See Fig 8. Porritt et al 2014


NW-SE cross-section across the Colorado Plateau showing the two lithospheric drips. See Fig 13 Obrebski et al 2011

DNA10-S

The DNA10-S model integrates teleseismic body-wave traveltime and surface-wave phase velocity measurements into a single inversion to constrain the S-wave velocity structure beneath the western US (from the Pacific coast to ~100 deg W, from Mexico to Canada). By combining these datasets we can constrain both the lithospheric structure, with a horizontal resolution of ~100km and vertical resolution of ~10 km, and the mantle structure to 1000km depth with a resolution of ~250 km. This allows imaging of the process of mantle convection and its interaction with the lithosphere. The stable and old Colorado Plateau is imaged with two high-velocity and cylindrical anomalies extending into the mantle below. These are interpreted as lithospheric drips and can explain the Cenozoic uplift of the plateau. The low-velocity S-shaped plume conduit beneath Yellowstone extends from the lower mantle up to the active caldera and then spreads out beneath the Snake River Plain. For the first time we can image the parabola shape of the residual plume material that is aligned exactly with the surface tectonic parabola. Subduction has been ongoing beneath the Pacific Northwest for more than 150Ma. Today's high-velocity slab is imaged in the mantle, along with a series of similar features to the east of the current slab. These are interpreted as fossil slab fragments of the Farallon plate. The complex S-shape of the Yellowstone plume is a result of the plume weaving a path to the surface between these slab fragments. Obrebski, Allen, Pollitz and Hung GJI, 2011

DNA10-S information, download and slice

DNA09

The DNA09-P and DNA09-S velocity models are the first to use finite frequency sensitivity kernels for the teleseismic traveltime observations. The Earthscope dataset extends up to July 2009 providing good resolution as far east as ~105 deg W (beyond the Rocky Mountains) and to a depth of 1000 km with resolution on a scale of ~200 km. The P- and S-velocity models show a plume extending from the lower mantle to the surface beneath Yellowstone, and a shallow and fragmented Juan de Fuca slab. The complex geometry is interpreted as being due to interactions between the plume and slab and can explain the unusual characteristics of the Cascadia subduction system including the absence of deep earthquakes and trench-perpendicular orientation of seismic anisotropy. Obrebski, Allen, Xue and Hung GRL, 2010

DNA09 information, download and slice

Anisotropy

The DNA07 and DNA09 models are isotropic P- and S-velocity models. Anisotropy is investigated beneath the western US by Eakin et al 2010. Shear-wave splitting measurements are used to constrain anisotropy in the upper few hundred kilometers. These observations are then interpreted in concert with the DNA09 velocity structure. Along the length of Cascadia the fast direction is found to be consistently trench-normal. The Cascadia subduction zone is one of only two subduction zones where this is the case. The conclusion is that the asthenosphere offshore Cascadia is being entrained in the subduction of the Juan de Fuca plate. At the Mendocino Triple Junction there is a rapid rotation of the fast direction. Through comparison with the velocity structure (see fig right) this is interpreted as being flow around the southern edge of the Juan de Fuca slab. Read all about it in Eakin et al 2010 (the shear-wave splitting observations are including in the manuscript pdf).

DNA07

The DNA07-P and DNA07-S velocity models are the first in the DNA series. They use Earthscope data up until October 2007 and image the US from the Pacific coast to ~110 deg W. The ray-theoretical inversion uses relative teleseismic traveltime measurements to image mantle structure to ~750 km depth with a resolution of ~200 km. The P- and S-velocity model show the shallow extent of the Juan de Fuca subduction window, the low-velocity slab gap to the south and the northwest dipping anomaly beneath Yellowstone. Xue and Allen JGR, 2010

DNA07 information, download and slice


Acknowledgements

The following have contributed to the development of the DNA models: Richard Allen (UC Berkeley) Shu-Huei Hung (National Taiwan University) Mathias Obrebski (UC Berkeley) Robert Porritt (UC Berkeley) Fred Pollitz (USGS) Mei Xue (formerly UC Berkeley, now Tongji University)

Support for this project is provided by the Earthscope program of the National Science Foundation, and the University of California, Berkeley. The 3D visualization has been facilitated by the Keck Caves of the University of California, Davis.


This page is maintained by Richard Allen