Sub-slab anisotropy beneath the Sumatra and circum-Pacific subduction zones from source-side shear wave splitting observations

2014 ◽  
Vol 15 (6) ◽  
pp. 2262-2281 ◽  
Author(s):  
Colton Lynner ◽  
Maureen D. Long
Keyword(s):  
Shear Wave ◽  
Subduction Zones ◽  
Shear Wave Splitting ◽  
Wave Splitting

Anisotropy-revealed change in hydration along the Alaska subduction zone

Geology ◽  
2021 ◽  
Author(s):  
Colton Lynner
Keyword(s):  
Subduction Zone ◽  
Shear Wave ◽  
Subduction Zones ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Pacific Plate ◽  
Seismic Gap ◽  
Megathrust Earthquakes ◽  
Wave Splitting ◽  
Subducting Slab

Megathrust earthquake behavior in subduction zones is controlled by a variety of factors including the hydration state of the subducting slab. Increased hydration reduces the occurrence of great, damaging earthquakes by diminishing the strength of the material along the interface between tectonic plates. Understanding variations in hydration in subductions zones is necessary for properly assessing the overall hazard posed by each region. Fortunately, seismic anisotropy is strongly dependent upon hydration of the subducting crust and lithosphere. I present shear-wave splitting measurements that illuminate changes in anisotropy, and therefore hydration, of the subducting Pacific plate beneath the Alaska subduction zone (northern Pacific Ocean). Variations in shear-wave splitting directly correlate to changes in the behavior of great, megathrust earthquakes. My measurements show that the Shumagin seismic gap is characterized by a hydrated subducting slab, explaining the long-term lack of great earthquakes. Observations in the immediately adjacent Semidi segment, which experiences great events regularly, indicate a far less hydrated slab. These results are driven by the preferential alignment of paleo-spreading fabrics of the Pacific plate. Where fabrics are more closely aligned with the orientation of the trench, outer-rise faulting and plate hydration is enhanced. These results highlight the importance of changes in preexisting slab structures and subsequent hydration in the production of great, damaging earthquakes.

scholarly journals Shear Wave Splitting and Mantle Flow in Mexico: What Have we Learned?

2017 ◽  
Vol 56 (2) ◽  
Author(s):  
Raúl W. Valenzuela ◽  
Gerardo León Soto
Keyword(s):  
Shear Wave ◽  
Slow Wave ◽  
Upper Mantle ◽  
Subduction Zones ◽  
Seismic Anisotropy ◽  
Shear Wave Splitting ◽  
Special Focus ◽  
Mantle Flow ◽  
Wave Splitting

A review is presented of the shear wave splitting studies of the upper mantle carried out in Mexico during the last decade. When a seismic wave enters an anisotropic medium it splits, which means that a fast and a slow wave are produced. Two parameters are used to quantify anisotropy. These are the fast polarization direction and the delay time between the fast and the slow wave. An example of the measurement technique is presented using an SKS phase because most observations are based on teleseismic data. Results of two studies using local S waves from intraslab earthquakes are also discussed. Key aspects of the interpretation of splitting measurements are explained. These include the depth localization of anisotropy, the relation-ship between olivine fabrics and mantle flow, the role of absolute plate motion, and the role of relative plate motions with a special focus on subduction zones. An important motivation for studying seismic anisotropy is that it makes it possible to constrain the characteristics of upper mantle flow and its relationship to tectonic processes. Mexico has many diverse tectonic environments, some of which are currently active, or were formerly active, and have left their imprint on seismic anisotropy. This has resulted in a wide variety of mechanisms for driving mantle flow. Broadly speaking, the discussion is organized into the following regions: Baja California peninsula, Western Mexican Basin and Range, northern and northeastern Mexico, the Middle America Trench, the Yucatán peninsula, and lowermost mantle anisotropy. Depending on the unique characteristics encountered within each region, the relationship between anisotropy and mantle flow is explored.

Analysis of shear wave splitting anisotropy in the Tres Virgenes Volcanic Complex, Baja California Sur, Mexico

Geothermics ◽  
2021 ◽  
Vol 94 ◽  
pp. 102115
Author(s):  
F. Chacón-Hernández ◽  
F.R. Zúñiga ◽  
J.O. Campos-Enríquez ◽  
J. Lermo-Samaniego ◽  
N. Jiménez-Méndez
Keyword(s):  
Shear Wave ◽  
Baja California ◽  
Shear Wave Splitting ◽  
Volcanic Complex ◽  
Baja California Sur ◽  
Wave Splitting

Effects of oil‐water saturation on shear‐wave splitting in multicomponent seismic data

2007 ◽  
Author(s):  
Zhongping Qian ◽  
Xiang‐Yang Li ◽  
Mark Chapman ◽  
Yonggang Zhang ◽  
Yanguang Wang
Keyword(s):  
Shear Wave ◽  
Seismic Data ◽  
Water Saturation ◽  
Shear Wave Splitting ◽  
Multicomponent Seismic ◽  
Wave Splitting ◽  
Oil Water
Sign in / Sign up

Export Citation Format

Share Document