We present a method for imaging quasi-vertically dipping faults with
surface records of reflected P waves from small earthquakes. Faults
are boundaries between geological structures, such as tectonic plates,
and are located in earthquake active regions such as Parkfield, California.
The high degree of seismic activity enables the use of multiple seismic
recordings in our fault identification algorithm. Major challenges
occur because of the quasi-vertical orientation of the fault and
the fact that the wave reflected by the fault and recorded by the
surface receivers is not well modelled by the direct arrival of the
propagating wave generated by the earthquake source. Our method uses
the 2-D acoustic wave equation as the model for P-wave propagation.
We assume that an approximate wave speed map on the reflection side
of the fault is available and the source locations are known, for
example, from traveltime tomography. We also assume that the source
time function is known. The new features of our method arise because
earthquake sources are located very close to the fault. This has
two implications: (1) the direct arrival and the reflected wave arrive
almost simultaneously, so that it is impossible to separate them
on a seismogram using standard techniques, and (2) most of the reflections
occur above the critical angle which introduces a distortion in the
reflected wave. To overcome these difficulties we use a modelled
incident wave to (1) remove the direct arrival from the data, and
(2) remove the post-critical distortion from the reflected wave.
We justify the distortion removal using the leading-order term of
an asymptotic expansion, and an optimization procedure. To complete
our algorithm we utilize some features of reverse time migration:
(1) the use of full acoustic wave equation for modelling and backpropagation,
and (2) zero-lag correlation of the backpropagated time reversed
reflected and incident fields. We present numerical examples of fault
reconstructions with synthetic data.
%0 Journal Article
%1 zheglova_etal:2012
%A Zheglova, P.
%A McLaughlin, J. R.
%A Roecker, S. W.
%A Yoon, J. R.
%A Renzi, D.
%D 2012
%I Blackwell Publishing Ltd
%J Geophysical Journal International
%K geophysics seismology
%N 3
%P 1584--1596
%R 10.1111/j.1365-246X.2012.05424.x
%T Imaging quasi-vertical geological faults with earthquake data
%U http://dx.doi.org/10.1111/j.1365-246X.2012.05424.x
%V 189
%X We present a method for imaging quasi-vertically dipping faults with
surface records of reflected P waves from small earthquakes. Faults
are boundaries between geological structures, such as tectonic plates,
and are located in earthquake active regions such as Parkfield, California.
The high degree of seismic activity enables the use of multiple seismic
recordings in our fault identification algorithm. Major challenges
occur because of the quasi-vertical orientation of the fault and
the fact that the wave reflected by the fault and recorded by the
surface receivers is not well modelled by the direct arrival of the
propagating wave generated by the earthquake source. Our method uses
the 2-D acoustic wave equation as the model for P-wave propagation.
We assume that an approximate wave speed map on the reflection side
of the fault is available and the source locations are known, for
example, from traveltime tomography. We also assume that the source
time function is known. The new features of our method arise because
earthquake sources are located very close to the fault. This has
two implications: (1) the direct arrival and the reflected wave arrive
almost simultaneously, so that it is impossible to separate them
on a seismogram using standard techniques, and (2) most of the reflections
occur above the critical angle which introduces a distortion in the
reflected wave. To overcome these difficulties we use a modelled
incident wave to (1) remove the direct arrival from the data, and
(2) remove the post-critical distortion from the reflected wave.
We justify the distortion removal using the leading-order term of
an asymptotic expansion, and an optimization procedure. To complete
our algorithm we utilize some features of reverse time migration:
(1) the use of full acoustic wave equation for modelling and backpropagation,
and (2) zero-lag correlation of the backpropagated time reversed
reflected and incident fields. We present numerical examples of fault
reconstructions with synthetic data.
@article{zheglova_etal:2012,
abstract = {We present a method for imaging quasi-vertically dipping faults with
surface records of reflected P waves from small earthquakes. Faults
are boundaries between geological structures, such as tectonic plates,
and are located in earthquake active regions such as Parkfield, California.
The high degree of seismic activity enables the use of multiple seismic
recordings in our fault identification algorithm. Major challenges
occur because of the quasi-vertical orientation of the fault and
the fact that the wave reflected by the fault and recorded by the
surface receivers is not well modelled by the direct arrival of the
propagating wave generated by the earthquake source. Our method uses
the 2-D acoustic wave equation as the model for P-wave propagation.
We assume that an approximate wave speed map on the reflection side
of the fault is available and the source locations are known, for
example, from traveltime tomography. We also assume that the source
time function is known. The new features of our method arise because
earthquake sources are located very close to the fault. This has
two implications: (1) the direct arrival and the reflected wave arrive
almost simultaneously, so that it is impossible to separate them
on a seismogram using standard techniques, and (2) most of the reflections
occur above the critical angle which introduces a distortion in the
reflected wave. To overcome these difficulties we use a modelled
incident wave to (1) remove the direct arrival from the data, and
(2) remove the post-critical distortion from the reflected wave.
We justify the distortion removal using the leading-order term of
an asymptotic expansion, and an optimization procedure. To complete
our algorithm we utilize some features of reverse time migration:
(1) the use of full acoustic wave equation for modelling and backpropagation,
and (2) zero-lag correlation of the backpropagated time reversed
reflected and incident fields. We present numerical examples of fault
reconstructions with synthetic data.},
added-at = {2012-09-01T13:08:21.000+0200},
author = {Zheglova, P. and McLaughlin, J. R. and Roecker, S. W. and Yoon, J. R. and Renzi, D.},
biburl = {https://www.bibsonomy.org/bibtex/21f71827cc61b7894c84e0f6507474a26/nilsma},
doi = {10.1111/j.1365-246X.2012.05424.x},
interhash = {e5caf1ed5b39352d9855d9bfc76517ef},
intrahash = {1f71827cc61b7894c84e0f6507474a26},
journal = {Geophysical Journal International},
keywords = {geophysics seismology},
number = 3,
pages = {1584--1596},
publisher = {Blackwell Publishing Ltd},
timestamp = {2021-02-09T13:27:42.000+0100},
title = {Imaging quasi-vertical geological faults with earthquake data},
url = {http://dx.doi.org/10.1111/j.1365-246X.2012.05424.x},
volume = 189,
year = 2012
}