Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
Collection
For ¥0.57 per day, unlimited downloads CREATE MEMBERSHIP Download

toTop

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

home > search >

Seismic scatterers at the shallowest lower mantle beneath subducted slabs

Author:
Kaneshima, Satoshi  


Journal:
EARTH AND PLANETARY SCIENCE LETTERS


Issue Date:
2009


Abstract(summary):

Data from a western United States short-period seismic network are analyzed in order to investigate anomalous later phases within a time window from about 10 s to 120 s after direct P waves for deep and intermediate-depth earthquakes in circum-Pacific subduction zones. The anomalous phases are best interpreted as S-to-P scattered waves (wavelengths of similar to 10 km) from heterogeneities in the shallow lower mantle (depths <= 950 km). Several S-to-P scatterers where elastic properties of the rocks must substantially change within several kilometers are detected in the shallowest 300 km of the lower mantle beneath four circum-Pacific regions: Kuril, Bonin, Fiji, and Peru. Around most of the observed scatterers the seismic tomography models have delineated high seismic velocity anomalies which are associated with recently subducted Pacific slab or Nazca slab. The most likely origin of the scatterers would be basalt which used to form the oceanic crust. Interestingly enough the majority of the scatterers are located near the bottom boundaries of the slabs. Given rather moderate degrees of folding and/or buckling of the Pacific and Nazca slabs in the shallowest lower mantle at the study areas, the existence of the oceanic crust associated with the most recent slab subduction at the scattering sites is unlikely. Alternative and more likely explanations include: the presence of ancient basaltic rocks, localized dehydration of hydrous minerals, or a sharp boundary between different rock fabrics such as isotropic and anisotropic lower mantle rocks associated with mantle flow dragged by the slab subduction. (C) 2009 Elsevier B.V. All rights reserved.


Page:
304---315


VIEW PDF

The preview is over

If you wish to continue, please create your membership or download this.

Create Membership

Similar Literature

Submit Feedback

This function is a member function, members do not limit the number of downloads