Necessary Conditions for Intraplate Seismic Zones in North America

Clustering of contact zones, hybrid zones, and phylogeographic breaks in North America.

A recent test for the existence of suture zones in North America, based on hybrid zones studied since 1970, found support for only two of the 13 suture zones identified by Remington in 1968 (Swenson and Howard 2004). One limitation of that recent study was the relatively small number of hybrid zones available for mapping. In this study, we search for evidence of clustering of contact zones betw...

Temporal variation of large intraplate earthquakes in coupled subduction zones

The focal mechanisms of intraplate earthquakes within subducting lithosphere are frequently used to infer large-scale stress regimes induced by slab-pull, bending or unbending, and lateral segmentation and undulations of the slab . Numerous studies have further postulated that the intraplate activity is influenced by transitory regional stress regimes such as those associated with interplate th...

Evidence for bimodal hybrid zones between two species of char (Pisces: Salvelinus) in northwestern North America.

Dolly Varden (Salvelinus malma, Pisces: Salmonidae) and bull trout (Salvelinus confluentus) have widely overlapping, but largely parapatric ranges in watersheds in northwestern North America from Washington State to northern British Columbia. Genetic analysis of natural populations using diagnostic molecular markers revealed widespread local sympatry and hybridization with hybrids comprising 0-...

3D Flexure and intraplate compression in the North Sea Basin

We apply a recently developed 3D flexure model incorporating lateral variations in flexural rigidity (EET) and necking depth (zn) to study the 3D effects of intraplate stresses on Quaternary accelerated subsidence and uplift in the North Sea Basin and adjacent areas. In the model approach lateral variations and magnitude of predicted Quaternary vertical motions are largely dependent on the pre-...

Some Results on Necessary Conditions for Tow Quasidifferentiable Optimization Problems