scholarly journals An analysis of recorded and simulated SH wave reverberations in the upper mantle beneath the USArray

2022 ◽  
Author(s):  
Meichen Liu ◽  
Jeroen Ritsema ◽  
Carlos Chaves
Keyword(s):  
Upper Mantle ◽  
Sh Wave

Love wave or slip wave?

2021 ◽  
Author(s):  
Ranjith Kunnath
Keyword(s):  
Elastic Wave ◽  
Upper Mantle ◽  
Love Wave ◽  
Wave Dispersion ◽  
Sh Wave ◽  
The Earth ◽  
Seismic Frequencies ◽  
New Type ◽  
Love Wave Dispersion ◽  
Frictional Slip

<p>A model that explains the anomalies in the Love wave dispersion in the earth is presented. Conventionally, welded contact between the crust and the upper mantle is assumed, leading to Love wave generation when the earth is excited. However, the observations of SH wave dispersion at seismic frequencies is at variance with this model, at least for some crustal plates (Ekström, 2011). When frictional slip occurs at the crust-upper mantle interface, a new type of interfacial elastic wave called the antiplane slip wave can occur (Ranjith, 2017). It is shown that the antiplane slip waves can explain the observed anomalies in the Love wave dispersion. </p>

SH-Wave Scattering From the Interface Defect

2017 ◽  
Vol 5 (1) ◽  
pp. 45-50
Author(s):  
Myron Voytko ◽  
◽  
Yaroslav Kulynych ◽  
Dozyslav Kuryliak
Keyword(s):  
Half Space ◽  
Wave Diffraction ◽  
Scattered Field ◽  
Wave Scattering ◽  
Elastic Layer ◽  
Analytical Form ◽  
Structure Parameters ◽  
Sh Wave ◽  
Interface Defect ◽  
Hopf Method

The problem of the elastic SH-wave diffraction from the semi-infinite interface defect in the rigid junction of the elastic layer and the half-space is solved. The defect is modeled by the impedance surface. The solution is obtained by the Wiener- Hopf method. The dependences of the scattered field on the structure parameters are presented in analytical form. Verifica¬tion of the obtained solution is presented.

Water Gas May Not Shift in Deep Earth

2020 ◽  
Author(s):  
Nore Stolte ◽  
Junting Yu ◽  
Zixin Chen ◽  
Dimitri A. Sverjensky ◽  
Ding Pan
Keyword(s):  
Formic Acid ◽  
Upper Mantle ◽  
Free Energy Calculations ◽  
Water Gas Shift ◽  
Ab Initio Molecular Dynamics ◽  
Water Gas Shift Reaction ◽  
Carbon Carrier ◽  
Deep Earth ◽  
Shift Reaction ◽  
Water Gas

The water-gas shift reaction is a key reaction in Fischer-Tropsch-type synthesis, which is widely believed to generate hydrocarbons in the deep carbon cycle, but is little known at extreme pressure-temperature conditions found in Earth’s upper mantle. Here, we performed extensive ab initio molecular dynamics simulations and free energy calculations to study the water-gas shift reaction. We found the direct formation of formic acid out of CO and supercritical water at 10∼13 GPa and 1400 K without any catalyst. Contrary to the common assumption that formic acid or formate is an intermediate product, we found that HCOOH is thermodynamically more stable than the products of the water-gas shift reaction above 3 GPa and at 1000∼1400 K. Our study suggests that the water-gas shift reaction may not happen in Earth’s upper mantle, and formic acid or formate may be an important carbon carrier, participating in many geochemical processes in deep Earth.<br>

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