Ambient noise seismic monitoring of the continuous deformation of the Earth

SUMMARY A network of seismometers has been installed on the Gugla rock glacier since October 2015 to estimate seismic velocity changes and detect microseismicity. These two processes are related to mechanical and structural variations occurring within the rock glacier. Seismic monitoring thus allows a better understanding of the dynamics of rock glaciers throughout the year. We observed seasonal variations in seismic wave velocity and microseismic activity over the 3 yr of the study. In the first part of our analysis, we used ambient noise correlations to compute daily changes of surface wave velocity. In winter, seismic wave velocities were higher, probably due to refreezing of the permafrost active layer and cooling of the uppermost permafrost layers, leading to increased overall rigidity of the medium. This assumption was verified using a seismic model of wave propagation that estimates the depth of P- and S-wave velocity changes from 0 down to 10 m. During melting periods, both a sudden velocity decrease and a decorrelation of the seismic responses were observed. These effects can probably be explained by the increased water content of the active layer. In the second part of our study, we focused on detecting microseismic signals generated in and around the rock glacier. This seismic activity (microquakes and rockfalls) also exhibits seasonal variations, with a maximum in spring and summer, which correlates principally with an exacerbated post-winter erosional phase of the front and a faster rock glacier displacement rate. In addition, we observed short bursts of microseismicity, both during snowfall and during rapid melting periods, probably due to pore pressure increase.

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Teleseismic correlations of ambient seismic noise for deep global imaging of the Earth

Geophysical Journal International ◽

10.1093/gji/ggt160 ◽

2013 ◽

Vol 194 (2) ◽

pp. 844-848 ◽

Cited By ~ 81

Author(s):

P. Boué ◽

P. Poli ◽

M. Campillo ◽

H. Pedersen ◽

X. Briand ◽

...

Keyword(s):

Seismic Noise ◽

Ambient Noise ◽

Inner Core ◽

Global Analysis ◽

Imaging Study ◽

Ambient Seismic Noise ◽

Core Mantle Boundary ◽

The Core ◽

The Earth ◽

Earthquake Data

Abstract We present here a global analysis showing that wave paths probing the deepest part of the Earth can be obtained from ambient noise records. Correlations of seismic noise recorded at sensors located various distances apart provide new virtual seismograms for paths that are not present in earthquake data. The main arrivals already known for earthquake data are also present in teleseismic correlations sections, including waves that have propagated through the Earth's core. We present examples of applications of such teleseismic correlations to lithospheric imaging, study of the core mantle boundary or of the anisotropy of the inner core.

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Passive Seismic Monitoring Study of the Earth Degassing in the Arctic

10.3997/2214-4609.202050102 ◽

2020 ◽

Cited By ~ 1

Author(s):

V. Bogoyavlensky ◽

R. Nikonov ◽

G. Erokhin ◽

V. Bryskin

Keyword(s):

Seismic Monitoring ◽

The Arctic ◽

The Earth ◽

Monitoring Study ◽

Passive Seismic

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Definition and identification of seismic events in the USSR in 1971

Bulletin of the Seismological Society of America ◽

10.1785/bssa0643-10607 ◽

1974 ◽

Vol 64 (3-1) ◽

pp. 607-636

Author(s):

Ola Dahlman ◽

Hans Israelson ◽

Atle Austegard ◽

Gunnel Hörnström

Keyword(s):

Focal Depth ◽

Seismic Monitoring ◽

Seismic Events ◽

Long Period ◽

The Earth ◽

Short Period ◽

Complete Test ◽

Period Data ◽

Test Ban ◽

Test Ban Treaty

abstract Seismic events reported to have occurred in the USSR in 1971 are studied to assess the seismic monitoring problem as it may occur in the context of a complete test-ban treaty. Available epicenter data of a total of 199 events, 180 earthquakes and 19 explosions, are presented. Focal depth estimates reported by the National Oceanic and Atmospheric Administration, U.S., and the Institute of Physics of the Earth, Moscow, are compared. Identification parameters determined using short- and long-period data from Hagfors Observatory and supplementary short-period data from the Yellowknife array station in Canada are presented. To study the combined operative efficiency and applicability of available identification parameters, the reported depth estimates and the identification data are assessed in a defined way.

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Seismic velocity changes caused by the Earth tide: Ambient noise correlation analyses of small-array data

Geophysical Research Letters ◽

10.1002/2014gl060690 ◽

2014 ◽

Vol 41 (17) ◽

pp. 6131-6136 ◽

Cited By ~ 16

Author(s):

Tomoya Takano ◽

Takeshi Nishimura ◽

Hisashi Nakahara ◽

Yusaku Ohta ◽

Sachiko Tanaka

Keyword(s):

Ambient Noise ◽

Seismic Velocity ◽

Earth Tide ◽

Noise Correlation ◽

Array Data ◽

The Earth ◽

Correlation Analyses ◽

Seismic Velocity Changes ◽

Small Array ◽

Velocity Changes

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Measurement of Radon concentration by Xenon gamma-ray spectrometer for seismic monitoring of the Earth

Journal of Physics Conference Series ◽

10.1088/1742-6596/675/4/042007 ◽

2016 ◽

Vol 675 (4) ◽

pp. 042007 ◽

Cited By ~ 2

Author(s):

A Novikov ◽

S Ulin ◽

V Dmitrenko ◽

K Vlasik ◽

O Bychkova ◽

...

Keyword(s):

Radon Concentration ◽

Gamma Ray ◽

Seismic Monitoring ◽

Gamma Ray Spectrometer ◽

The Earth

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Inverse Q -filter for seismic resolution enhancement

Geophysics ◽

10.1190/1.2192912 ◽

2006 ◽

Vol 71 (3) ◽

pp. V51-V60 ◽

Cited By ~ 188

Author(s):

Yanghua Wang

Keyword(s):

High Resolution ◽

Ambient Noise ◽

Quality Data ◽

Frequency Wave ◽

High Frequencies ◽

Seismic Resolution ◽

The Earth ◽

Text Filtering ◽

Text Model ◽

Layered Approach

A principal limitation on seismic resolution is the earth attenuation, or [Formula: see text]-effect, including the energy dissipation of high-frequency wave components and the velocity dispersion that distorts seismic wavelets. An inverse [Formula: see text]-filtering procedure attempts to remove the [Formula: see text]-effect to produce high-resolution seismic data, but some existing methods either reduce the S/N ratio, which limits spatial resolution, or generate an illusory high-resolution wavelet that contains no more subsurface information than the original low-resolution data. In this paper, seismic inverse [Formula: see text]-filtering is implemented in a stabilized manner to produce high-quality data in terms of resolution and S/N ratio. Stabilization is applied to only the amplitude compensation operator of a full inverse [Formula: see text]-filter because its phase operator is unconditionally stable, but the scheme neither amplifies nor suppresses high frequencies at late times where the data contain mostly ambient noise. The latter property makes the process invertible, differentiating from some conventional stabilized inverse schemes that tend to suppress high frequencies at late times. The stabilized inverse [Formula: see text]-filter works for a general earth [Formula: see text]-model, variable with depth or traveltime, and is more accurate than a layered approach, which involves an approximation to the amplitude operator. Because the earth [Formula: see text]-model can now be defined accurately, instead of a constant-[Formula: see text] layered structure, the accuracy of the inverse [Formula: see text]-filter is much higher than for a layered approach, even when implemented in the Gabor transform domain. For the stabilization factor, an empirical relation is proposed to link it to a user-specified gain limit, as in an explicit gain-controlling scheme. Synthetic and real data exam-ples demonstrate that the stabilized inverse [Formula: see text]-filter corrects the wavelet distortion in terms of shape and timing, compensates for energy loss without boosting ambient noise, and produces desirable seismic images with high resolution and high S/N ratio.

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The motion of a lunar orbiter

Symposium - International Astronomical Union ◽

10.1017/s0074180900105686 ◽

1966 ◽

Vol 25 ◽

pp. 373

Author(s):

Y. Kozai

Keyword(s):

Degrees Of Freedom ◽

Dimensional Space ◽

Artificial Satellite ◽

Equations Of Motion ◽

Triaxial Ellipsoid ◽

The Moon ◽

Secular Motion ◽

The Earth ◽

Close Satellite ◽

The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

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Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

Symposium - International Astronomical Union ◽

10.1017/s0074180900178404 ◽

1962 ◽

Vol 14 ◽

pp. 415-418

Author(s):

K. P. Stanyukovich ◽

V. A. Bronshten

Keyword(s):

Explosive Charge ◽

The Moon ◽

Meteorite Impacts ◽

The Earth ◽

Lunar Craters ◽

The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

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