Imaging D" Beneath Mexico Using American P Wave Data

Details Imaging D" Beneath Mexico Using American P Wave Data Imaging D" Beneath Mexico Using American P Wave Data

Dec 2003

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003agufm.u51b0010h&link_type=abstract

American Geophysical Union, Fall Meeting 2003, abstract #U51B-0010

Physics

7200 Seismology, 7203 Body Wave Propagation, 7207 Core And Mantle, 8147 Planetary Interiors (5430, 5724)

Scientific paper

Broadband data from North American permanent and temporary stations recording events 20-60 degrees away in Central America and northern South America are used to study the lower mantle by analyzing PcP, ScP and their precursors (topside reflections and back-scattered arrivals ). The lowermost few hundred km of the mantle, D", is physically and chemically more heterogeneous than the overlying bulk of the mantle and contains wavespeed variations rivaling those of the crust. Core-reflected and mid and lower mantle scattered P and S waves are typically low energy phases and some form of stacking is necessary to raise their signal-to-noise ratios to levels suitable for modeling and interpretation. We use two methods. Where data is limited, we bin data according to their reflection point on the CMB, and then perform simple 1D time-to-depth analysis of PcP (or ScP) precursors. P is used as a reference phase in order to reduce the travel time variations caused by upper mantle and crustal velocity heterogeneity. All data are source-normalized by deconvolution of a source-time function calculated from the data. Using this method, we hope to constrain ˜ 100 km variations in the height and strength of a D" reflector recognized regionally in earlier studies using stacks of short-period data. We will atempt to better characterize the strength and thickness of ultra low velocity zones found in this region in previous studies. In areas of greater data density, we will also use a stochastic migration method patterned after the Kirchhof Regional Migration method of Revenaugh (2000). This approach to migration offers greater immunity to artifacts than simple diffraction stacking, but offers similar resolution of scatterers and specular reflectors. Preliminary results reveal several bright reflections whose depth and strength change significantly between bins suggesting that the D" layer in this region is quite complex at scale lengths as small as one to two hundred km. The data also indicate high levels of D" scattering throughout the study region. To investigate shorter length scale variations, we are examining a 20 year span of short period data from the Pacific Northwest Seismograph Network.

Affiliated with

Also associated with

No associations

Rating

Imaging D" Beneath Mexico Using American P Wave Data does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Imaging D" Beneath Mexico Using American P Wave Data, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Imaging D" Beneath Mexico Using American P Wave Data will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1426483