Upper mantle structure of the Cascades from full-wave ambient noise tomography: Evidence for 3D mantle upwelling in the back-arc

Tomographic imaging of the Cascadia subduction zone: Constraints on the Juan de Fuca slab

“…A prominent low-V anomaly is located at the eastern edge of the study area under Oregon (Fig. 15a), which is consistent with flux melting related to the arc volcanism (Gao and Shen, 2014). The low-V anomalies at 40-60 km depths are consistent with the above-mentioned slab dehydration and eclogitization which are related to serpentinization of the forearc mantle.…”

“…10a, b, 12a and b), and the possible mechanism of the melt generation under those volcanoes is decompressional melting in the back-arc. This along-strike variation of low-V anomalies was also imaged by ambient noise tomography (Gao and Shen, 2014), and the lack of such a low-V zone along the entire arc indicates a variable strength of flux melting along the arc. Images from magnetotelluric transects of different segments of the Cascadia subduction zone also suggest that the melt generation in the Cascadia system is highly variable along the strike (e.g., Evans et al, 2014;Soyer and Unsworth, 2006).…”

“…1). Geodetic and geophysical observations also suggest along-strike segmentation of the plate motion, the recurrence rate of episodic tremor and slip (ETS), and melt generation with similar segment boundaries (Brudzinski and Allen, 2007;Gao and Shen, 2014;McCaffrey et al, 2007).…”

Full‐Wave Seismic Tomography in the Northeastern United States: New Insights Into the Uplift Mechanism of the Adirondack Mountains

“…These networks include EarthScope Transportable Array, Lamont-Doherty Cooperative Seismographic Network, Central and Eastern U.S. Network, New England Seismic Network, Canadian National Seismic Network, U.S. National Seismic Network, Pennsylvanian State Seismic Network, Portable Observatories for Lithospheric Analysis and Research Investigating Seismicity, Pennsylvania State Seismic Network, and Global Seismograph Network. The interstation distance was required to be at least 1.5 wavelength (e.g., Gao & Shen, 2014), which correspondingly limited the use of Rayleigh waves at long periods. To increase the signal-to-noise ratio, we stacked the daily cross-correlations for each station pair, which generated high-quality Rayleigh wave signals at periods of 5-150 s (see Figure S1 for examples of EGFs).…”

A new regime of slab-mantle coupling at the plate interface and its possible implications for the distribution of volcanoes

“…It appears that some other regions show similar features. We can see a good correlation between the clusters of volcanoes and low seismic wave velocity anomalies in the mantle wedge beneath the back arc in Cascades (Gao and Shen, 2014) and IzuBonin-Mariana (Isse et al, 2009), whose characteristic wavelengths are ∼300 and ∼500 km, respectively. It suggests that increasing the number of geophysical studies including the detailed image of seismic wave velocity will allow us to find the along-arc variation E-mail address: mmorishige@bep.vgs.kyoto-u.ac.jp. in the mantle wedge structure which is correlated with the volcanoes distribution in other subduction zones as well.…”