scholarly journals INVESTIGATION INTO 3D EARTH STRUCTURE AND SOURCES USING FULL SEISMIC WAVEFORMS

2014 ◽  
Author(s):  
◽  
Brian Covellone
Keyword(s):  
Earth Structure ◽  
Seismic Waveforms ◽  
3D Earth Structure

scholarly journals Influence of 3D Earth structure on Glacial Isostatic Adjustment in the Russian Arctic

2020 ◽  
Author(s):  
Tanghua Li ◽  
Nicole Khan ◽  
Alisa Baranskaya ◽  
Timothy Shaw ◽  
W Richard Peltier ◽  
...  
Keyword(s):  
Earth Structure ◽  
Glacial Isostatic Adjustment ◽  
Russian Arctic ◽  
Isostatic Adjustment ◽  
3D Earth Structure

scholarly journals Dependence of late glacial sea-level predictions on 3D Earth structure

2020 ◽  
Author(s):  
Meike Bagge ◽  
Volker Klemann ◽  
Bernhard Steinberger ◽  
Milena Latinovic ◽  
Maik Thomas
Keyword(s):  
Solid Earth ◽  
Sea Level ◽  
Seismic Tomography ◽  
Earth Structure ◽  
Glacial Cycle ◽  
Relative Sea Level ◽  
Last Glacial ◽  
Earth Structures ◽  
3D Earth Structure ◽  
The Last Glacial

<p><span>Glacial isostatic adjustment is dominated by Earth rheology resulting in a variability of relative sea-level (RSL) predictions of more than 100 meters during the last glacial cycle. Seismic tomography models reveal significant lateral variations in seismic wavespeed, most likely corresponding to variations in temperature and hence viscosity. Therefore, the replacement of 1D Earth structures by a 3D Earth structure is an essential part of recent research to reveal the impact of lateral viscosity contrasts and to achieve a more consistent view on solid-Earth dynamics. Here, we apply the VIscoelastic Lithosphere and MAntle model VILMA to predict RSL during the last deglaciation. We create an ensemble of geodynamically constrained 3D Earth structures which is based on seismic tomography models while considering a range of conversion factors to transfer seismic velocity variations into viscosity variations. For a number of globally distributed sites, we discuss the resulting variability in RSL predictions, compare this with regionally optimized 1D Earth structures, and validate the model results with relative sea-level data (sea-level indicators). This study is part of the German Climate Modeling initiative PalMod aiming the modeling of the last glacial cycle under consideration of a coupled Earth system model, i.e. including feedbacks between ice-sheets and the solid Earth.</span></p>

The First Very Broadband Mediterranean Network: 30 Yr of Data and Seismological Research

2019 ◽  
Vol 91 (2A) ◽  
pp. 787-802
Author(s):  
Silvia Pondrelli ◽  
Francesca Di Luccio ◽  
Laura Scognamiglio ◽  
Irene Molinari ◽  
Simone Salimbeni ◽  
...  
Keyword(s):  
Seismic Source ◽  
Global Scale ◽  
Anthropogenic Noise ◽  
Earth Structure ◽  
Backbone Network ◽  
Early Adoption ◽  
Stable Conditions ◽  
Remote Sites ◽  
The Mediterranean

Abstract Starting in 1988, with the installation of the first broadband (BB) instrument in Italy, the Mediterranean Very Broadband Seismographic Network (MedNet) program established a backbone network of BB stations of the highest quality in the Mediterranean Sea countries. The Mediterranean region is characterized by relevant and frequent seismicity related to its complex tectonics, due to the convergence of two major plates, Africa and Eurasia, and the involvement of other minor plates, as the Adriatic plate. Therefore, the MedNet project became a scientific research infrastructure of excellence, able to fill the gap of regional coverage when the availability of seismic BB instruments was still scarce. The main characteristics of the MedNet network are the highest quality of the seismographic instrumentation at remote sites and very low level of anthropogenic noise with stable conditions of pressure and temperature. After 30 yr of recordings, the MedNet program has proven that the early adoption of very BB instruments in selected sites have been the best choice. A large number of studies benefited from MedNet data, as seismic source computation and Earth structure reconstruction, at local and global scale. We present a concise overview of the contribution given by MedNet data in the last three decades to motivate and financially support the existence of this valuable infrastructure, and to further maintain this project.

scholarly journals Earthquake Source Investigation of the Kanallaki, March 2020 Sequence (North-Western Greece) Based on Seismic and Geodetic Data

2021 ◽  
Vol 13 (9) ◽  
pp. 1752
Author(s):  
Nikos Svigkas ◽  
Anastasia Kiratzi ◽  
Andrea Antonioli ◽  
Simone Atzori ◽  
Cristiano Tolomei ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Detailed Knowledge ◽  
Eurasian Plate ◽  
Distribution Models ◽  
Active Deformation ◽  
Strong Earthquakes ◽  
Seismic Waveforms ◽  
Northwestern Greece ◽  
North Western ◽  
Western Greece

The active collision of the Apulian continental lithosphere with the Eurasian plate characterizes the tectonics of the Epirus region in northwestern Greece, invoking crustal shortening. Epirus has not experienced any strong earthquakes during the instrumental era and thus there is no detailed knowledge of the way the active deformation is being expressed. In March 2020, a moderate size (Mw 5.8) earthquake sequence occurred close to the Kanallaki village in Epirus. The mainshock and major aftershock focal mechanisms are compatible with reverse faulting, on NNW-ESE trending nodal planes. We measure the coseismic surface deformation using radar interferometry and investigate the possible fault geometries based on seismic waveforms and InSAR data. Slip distribution models provide good fits to both nodal planes and cannot resolve the fault plane ambiguity. The results indicate two slip episodes for a N337° plane dipping 37° to the east and a single slip patch for a N137° plane dipping 43° to 55° to the west. Even though the area of the sequence is very close to the triple junction of western Greece, the Kanallaki 2020 activity itself seems to be distinct from it, in terms of the acting stresses.

Spectral ratio comparison between translation and rotational records from induced seismic events.

2021 ◽  
Author(s):  
Dariusz Nawrocki ◽  
Maciej Mendecki ◽  
Lesław Teper
Keyword(s):  
Seismic Data ◽  
Seismic Station ◽  
Spectral Ratio ◽  
Numerical Differentiation ◽  
Vertical Axis ◽  
Frequency Range ◽  
Signal Ratio ◽  
Seismic Waveforms ◽  
Seismic Tests ◽  
Rotation Spectrum

<p>The seismic observations of the rotational signals are a field of seismology that is constantly developed. The recent research concerns sensors technology and its potential application in seismic tests. This study presents the results of a comparative analysis of rotational and translational seismic records using the horizontal-to-vertical spectral ratio (HVSR) method. In terms of transitional signal ratio, we have used the name of HVSR, but in terms of rotational component spectra, we have introduced a torsion-to-rocking spectral ratio (TRSR) which corresponds to horizontal rotation spectrum to vertical rotation spectrum. It has to be noticed that rotation in the horizontal axes has a vertical character and rotation in the vertical axis has a horizontal character.</p><p>The comparison was carried out between velocity signals of translational and rotational records, as well as, between acceleration signals respectively. All seismic data were recorded by two independent sensors: the rotational seismometer and translational accelerometer at the Imielin station, located in the Upper Silesia Coal Basin (USCB), Poland. The seismic data composed of three-component seismic waveforms related to 56 recorded tremors which were located up to 1,5 km from the seismic station and they resulted from the coal extractions carried out in the neighboring coal mines. The rotational acceleration was obtained by numerical differentiation and the translational velocity was produced by numerical integration.</p><p>The conducted spectral analyses allowed to estimate the range of frequency in which the rotational HVSR and the corresponded translational HVSR are comparable. The analysis of HVSR/TRSR curves (in the selected frequency range of 1Hz to 10Hz) showed a strong correlation between the spectral ratios for the velocity signals (translational and rotational) in the frequency range of 1Hz to 2Hz. Respectively, the comparison of the accelerometer signals indicated the correlation between HVSR/TRSR curves in the frequency range of 1Hz to 3Hz. Moreover, both of the TRSR (for velocity and acceleration) showed additional maxima in the same frequency range of 3Hz to 5Hz. These relatively high-frequency maxima did not correspond to translational spectra.  </p>

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