IRIS Webinar in Spanish on YouTube:
El “Phase Weighted Stack” y el “Phase Cross-Correlation” para la extracción de señal en ruido sísmico .
Ambient Seismic Noise Analysis / Monitoring (primary and secondary microseisms, GEOSCOPE global seismic
network, seasonal variations of the noise, amplitude spectra, noise polarization, degree of elliptical polarization, climate impact,
Northern/Southern Hemisphere, monitoring Antarctica ice changes, deep water SM in North Atlantic using tide modulations,
SM from polarization analysis for Indian Ocean, SPSP Archipelago in equatorial Atlantic, ... ):
Efficient Signal Extraction from Ambient Noise Cross-correlations (time-frequency domain phase weighted stack,
phase cross-correlations, development, Green's functions, time and frequency domain normalization, GEOSCOPE, TAPAS array,
body waves (P-phases), surface waves (R1, R2), wavelets, resampling, dispersion measurements, ...):
Monitoring Subtle Medium Changes (hydromechanical changes, precursors to volcanic erruption, El Hierro, small earthquake swarm, Reykjanes geothermal reservoir,
phase cross-correlations and auto-correlations, ...):
Generation Mechanisms, Observations and Modelling Seismic Noise (generation of secondary microseisms, Longuet-Higgins (1950) & Hasselmann (1963),
numerical ocean wave model WAVEWATCH III + improvements (ice berg distribution, coastal reflections, parametrization,
..., see IOWAGA), GEOSCOPE, synthetic noise power spectra of seismic displacement, modelling noise spectra for several years, deep water sources,
theoretical development, array analyses, noise amplitudes, ...):
Ambient Noise Tomography (Rayleigh-wave, Group-velocity Maps of the Borborema Province (NE Brazil) and SW Iberia, global scale
group velocity maps and 3-D inversion, 3-D group velocity inversions for Colombia, Costa Rica, Portugal):
Necessary Condition in Seismic Interferometry (theoretical development, noise cross-term cancellation,
how much averaging needed? length of correlation windows and number of stacks, monitoring noise non-stationarity, analytic approach):
Statistical Redundancy of Instantaneous Phases (theoretical development, instantaneous phase coherence statistics,
instantaneous phase randomness characterization, noise cross-correlations, monitoring/characterizing ambient noise wavefield):
Measuring Group Velocities (robustly measure group velocities, time-frequency domain phase-weighted stack combined with data resampling and decision strategies):
Measuring Rayleigh Wave Ellipticity and Inversion (robustly measure Rayleigh wave ellipticity from ambient noise and event data, use time-frequency dependent polarization, non-linear inversion, velocity depth profiles and 3-D velocity maps, Greenland & Antartica, ...):
Ambient Noise and Event Coda Autocorrelations (zero-offset reflection response, orbiting surface waves, mapping crustal discontinuities, ... ):
Semi-Automated Group Velocity Determination (time-scale domain, resampling strategy,
analytic signals, phase coherence, robust group arrival detections/measurements ...):
Lateral Phase-Coherence Filter (time-frequency domain, inverse S-transform,
analytic signals, phase coherence, spatial averaging, array analysis, ...):
S-Transform versus Morlet Wavelet Transform
(new insights, comparisons and relations, ...):
Inverse S-Transform
(motivation, new strategy, comparison, examples, numerical realization, ...):
Window Length for Local Slant Stack Transform
(Adative optimum slowness resolution, derivation, examples, ...):
Time-Time Transform
(rewriting the TT-transform in a new and more direct way, giving an interpretation of its diagonal elements):
Time-Frequency Domain Degree of Polarization Filter
(time-frequency domain, spectral matrix, time,frequency and distance-slowness
dependent averaging of degree of polarization, ...):
Time-Domain Degree of Polarization Filter
(time domain, complex trace analysis, instantaneous polarization, comparison to eigen
approaches, covariance matrix, trade-off window
length and power, local slowness-dependent averaging of seismic polarization attributes,
...)
Sparsity-Promoting Polarization Approach in the Time-Frequency Domain
(rearranged eigenvalue decomposition approach, improving resolution, adaptive filtering, sparsity promoting regularization):
Phase Cross-Correlations (PCC) (design of new amplitude-unbiased correlation,
comparison to other methods, upper mantle discontinuities in Brazil
(220km, 410km, 510km, 660km), transition zone, examples, ...):
Phase Weighted Stacking (PWS) (analytic signals, phase coherence, amplitude-unbiased
coherence measure, non-linear stacking, vespagram, upper mantle discontinuities
(410km, 660km), transition zone, examples, ... ):
Mine Tailings Dam Collapse at Mariana (SE Brazil, 05/11/2015) (small magnitude earthquake sequence,
spatio-temporal relation of earthquakes and dam failure, seismic signals from mudflow,...):
Radar interferometry using Sentinel-1 C-band data (monitoring of surface variability in an active mine, Rio Tinto, South Spain,...):
GEO3BCN-CSIC News on AGEMERA (Agile Exploration and Geo-modelling for European Critical Raw Materials) proyect (There exist a lot of outreach in the different media. The following links take you to notes/press-releases by the GEO3BCN-CSIC.):
Regional Body Wave Tomography (P-waves, S-waves, Brazil, robustness and resolution
analyses, tectonics, upper mantle, ...):
Correlation Between Intraplate Seismicity and Tomography in SE and central Brazil (P-waves, Brazil,
no correlation of seismic areas with main geological provinces, higher seismic activity
in areas with low P-wave velocities at 150-250 km depth, intraplate force concentration in upper
crust, high seismicity in regions of thinner lithosphere, ...):
Regional and Global Ambient noise tomography (Rayleigh-wave, group-velocity maps of the Borborema Province, NE Brazil; global
scale group velocity maps and 3-D inversion; regional tomography, SW Iberia integrating seafloor- and
land-based data for group velocity maps and 3-D inversions; regional tomography, group velocities and 3-D inversions for Colombian Andes, group velocities and 3-D inversions for Costa Rica, Portugal):
Regional 3-D Velocity Models from Rayleigh Wave Ellipticity Inversions (Mapping uppermost crustal structure underneath Greenland Ice Sheet, sublacial structure interaction controls dynamics of ice sheet.):
Basin Discontinuities Through Ambient Noise Auto/Cross-correlations (Ebro Basin, Spain; Potiguar Basin, Brazil):
Basin Discontinuities Through Reverse Time Migration (Solimoes Basin, Amazon, Brazil; different image conditions, phase cross-correlation):
Basin Discontinuities/Structure through ambient noise studies: autocorrelations, horizontal to vertical spectra ratio, ambient noise Rayleigh wave tomography and band-pass filtered ambient noise amplitude mapping (Cerdanya Basin, Eastern Pyrenees, multi-method approach, high-density seismic network ):
Moho Discontinuity Through Receiver Functions and Ambient Noise Cross/Auto-Correlations, Rayleigh Wave Dispersion Analyses (Isla Grande of Tierra del Fuego, Argentina. 550 km long MASE profile along center Mexico. Central Iberian Massif using ambient noise autocorrelations and Global-Phase Seismic Interferometry):
Upper Mantle Discontinuities (Detection and identification of coda waves which have
been converted and/or reflected at upper mantle discontinuities):
410-km and 660-km Discontinuities Beneath Spain and Morocco (Detection and identification of coda waves which have
been converted and/or reflected at upper mantle discontinuities, Eurasian-African Plate boundary at south Spain and north Morocco, cross-correlations, TopoIberia, Alboran slab, constraints on temperature and composition, depth profiles, ...):
Stutzmann et al., 2009 ;
Schimmel et al., 2011b ;
Beucler et al., 2015 ;
Davy et al., 2015 ;
de Queiroz et al., 2017 ;
Carvalho et al., 2019 .
Schimmel et al., 2011a ;
Schimmel et al., 2017 ;
Ventosa et al., 2017 ;
Schimmel et al., 2018 .
D'Hour et al., 2016 ;
Sanchez-Pastor et al., 2018 ;
Sanchez-Pastor et al., 2019 .
Mainly Rayleigh waves:
Ardhuin et al., 2011 ;
Stutzmann et al., 2012 ;
Obrebski et al., 2012 ;
Gualtieri et al., 2013 ;
Sergeant et al., 2013 .
Mainly body waves:
Obrebski et al., 2013 ;
Gualtieri et al., 2014 ;
Farra et al., 2016 ;
Meschede et al., 2017 ;
Meschede et al., 2019 .
Carreiro-Dias et al., 2015 ;
Haned et al., 2016 ;
Corela et al., 2017 ;
Poveda et al., 2018 ;
Nuñez et al., 2020 ;
Silveira et al., 2022 ;
Carvalho et al., 2022 .
Medeiros et al., 2015
(suppl. material ).
Gaudot et al., 2016 .
Schimmel et al., 2017 .
Berbellini et al., 2019 ;
Jones et al., 2021 .
Romero & Schimmel, 2018 ;
Schimmel et al., 2018 ;
Andres et al., 2019 ;
Buffoni et al., 2019 ;
Andres et al., 2020 ;
Compaire et al., 2021 ;
Kim et al., 2021 ;
Knapmeyer-Endrun et al., 2021 ;
Schimmel et al., 2021 .
Castro-Artola et al., 2022 ;
Signal Detection, Noise Attenuation, Filter Design, Theory and Applications:
Schimmel et al., 2017 .
Schimmel and Gallart, 2007 .
Ventosa et al., 2008 .
Schimmel and Gallart, 2005 ;
Schimmel and Gallart, 2007 ;
Simon et al., 2007 .
Ventosa et al., 2012 , pdf .
Simon et al. (2008) .
Schimmel and Gallart, 2004 .
Schimmel and Gallart, 2003 .
Mohammadigheymasi et al., 2022.
Schimmel, 1999 ,
summary with selected examples (HTML)
Schimmel and Paulssen, 1997 .
Examples: Note that there are very nice observations/applications published by
many other researchers.
Monitoring Mines:
Agurto-Detzel et al., 2016 .
Escayo et al., 2022 .
2022/11/14 (Español);
2022/11/14 (English);
Seismic Tomography:
Schimmel et al., 2003 ,
seismic velocity anomaly model for SE Brazil, summary with selected examples (HTML),
Rocha et al., 2011 ,
Simoes Neto et al., 2019 ,
P-wave and S-wave velocity model published in Schimmel et al. (2003) :
models (tar & bzip2 file) See end of this webpage for further information.
Assumpção et al., 2004 ,
Rocha et al., 2016 .
Carreiro-Dias et al., 2015 ;
Haned et al., 2016 ;
Corela et al., 2017 ;
Poveda et al., 2018 ;
Nuñez et al., 2020 ;
Silveira et al., 2022 ;
Carvalho et al., 2022 .
Jones et al., 2021 .
Mapping Discontinuities inside Earth:
Romero and Schimmel, 2018 ;
Dantas et al., 2018 .
Costa et al., 2018 .
Diaz et al., 2022 .
Buffoni et al., 2018 ;
Buffoni et al., 2019 ;
Andres et al., 2019 ;
Andres et al., 2020 ;
Castro-Artola et al., 2022 .
Schimmel and Paulssen,1997 ;
Schimmel, 1999 ;
Bonatto et al., 2013 (supplement) ;
D" Discontinuities (Detection and identification of ScS (sScS and ScS2) precursors,
focussing analysis to explain waveforms, modelling waveform variability and amplitudes,
synthetic seismograms, Kirchhoff-Helmholtz theory.)
Schimmel and Paulssen, 1996
Urban Seismology (City educational seismic networks. Connecting earth sciences and society. Characterization of seismic sources in urban environments(Barcelona, Brasila)):
GEO3BCN-CSIC News Distributed acoustic sensing (DAS) experiment in Barcelona. The following link takes you to the news:
Seminar (Spanish) on YouTube, organized by the "Residencia d'investigadors, ciclo: SOS! Aqui la Tierra":
Sismología en Marte: la Misión Insight .
Pre-Deployment Analyses (Blind test for Martian seismicity. Analysis of global-scale Martian pressure and wind variations, corresponding contributions to the Martian hum, and detectability. Low-frequency ambient noise autocorrelations: Waveforms and normal modes.):
First Seismic Analyses of Mars using InSight Data (Constraints of seismic structure on Mars from Marsquakes, dust devils, and noise. Scattering and attenuation. Characterisation of seismic noise, e.g., polarization as function of time and frequency. Seismic activity of Mars, Marsquake catalogue, data validation. Seismic receiver functions, ambient wavefield autocorrelations (seismic interferometry), H/V spectral ratios, surface wave evidence and structure, S-to-P- and P-to-S-wave conversions, distant events, crustal thickness, anisotropy, discontinuities, core radius, core reflections, ...):
GEO3BCN-CSIC News (There exist a lot of outreach in the different media. The following links take you to notes/press-releases by the GEO3BCN-CSIC):
Rainfall Reconstruction Through Annually Laminated Lake Sediments
(Rainfall reconstruction, Iberian Peninsula, Calcite laminated sediment, North Atlantic Oscillation
periodograms, climate variability,...):
Premature Neonates
(analysis of circadian and ultradian rhythmicities, premature babies, incubator, insulated skin
temperature, environmental influence, folding algorithm, phasor walk out method,
periodograms, ...):
Activity of Cave Crickets (Strinatia brevipennis)
(analysis of rhythmicities through different methods, new phase weighted folding algorithm,
evidence for circadian rhythmicities, isolation of environmental influence, controlled variation of
environmental influences, ...):
Bio-Medical Rhythm Detection
(non-sinoidal rhythms, new folding algorithm, Lomb-Scargle
periodograms, benefits and limitations, unequally spaced data, ...):
Diaz et al., 2020 ;
Maciel et al., 2021 .
2021/05/06 (Spanish) ;
2021/05/06 (English)
Planetary Seismology / Seismology on Mars:
Schimmel, Stutzmann, Ventosa, 2018 ;
Nishikawa, Lognonné, Kawamura, et al., 2019 ;
van Driel, Ceylan, Clinton, et al., 2019.
Giardini, Lognonné, Banerdt, et al., 2020 (see also Supplementary Material) ;
Lognonne, Banerdt, Pike, et al., 2020 (see also Supplementary Material) ;
Drilleau, Beucler, Lognonné, et al., 2020 ;
Scholz, Widmer-Schnidrig, Davis, et al., 2020 ;
Ceylan, Giardini, Boese, et al., 2021 ;
Compaire, Margerin, Garcia, et al., 2021 ;
Dahmen, Zehnhäusern, Clinton, et al., 2021 ;
Kim, Davis, Lekic, et al., 2021 ;
Knapmeyer-Endrun, Panning, Bissig, et al., 2021 (see also Supplementary Material) ;
Schimmel, Stutzmann, Lognonné, et al., 2021 ;
Stähler, Kahn, Banerdt, et al. 2021 (see also Supplementary Material) ;
Stutzmann, Schimmel, Lognonné, et al., 2021 ;
Carrasco, Knapmeyer-Endrun, Margerin, et al., 2022 ;
Horleston, Clinton, Ceylan, et al., 2022 ;
Kim, Banerdt, Ceylan, et al., 2022 ;
Li, Beghein, Wookey, et al., 2022 ;
Li, Beghein, Davis, et al., 2022 ;
2019/01/08 ;
2019/04/26 ;
2020/02/26 ;
2021/07/23 (English);
2021/07/23 (Español);
2022/10/27 (English);
2022/10/27 (Español);
2023/04/26 (Español);
2023/04/26 (English);
Climate Reconstructions from Geological Measurements:
Romero-Viana et al., 2011.
Bio-Medical Rhythm Detection, Theory and Applications:
Schimmel et al., 2002 .
Hoenen, Schimmel, Marques, 2001 .
Schimmel, 2001a ;
Schimmel, 2001b .
Ambient noise processing tools
Corr_stack_v04.3.tar:
Phase Cross Correlation and time-frequency Phase Weighted Stack as used in Schimmel et al. (2011a). Corr_stack_v04.3.tar is the latest release.
The tar file contains the source codes,
descriptions and 3 simple examples. My programs use SAC data and run on linux systems.
Corr_stack_v04.1.tar is the same as Corr_stack_v03.6.tar, but adapted for local parallelization through "OpenMP" (Open Multi-Processing)
which can be invoked during the compilation. Thus, Corr_stack_v04.x is much faster and this is the version which will be
continued.
Just download the tar file and open it with "tar xvf Corr_stack_v0x.x.tar".
(Previous versions: Corr_stack_v03.6.tar, Corr_stack_v03.5.tar,
Corr_stack_v04.2.tar).
DOI: 10.20350/digitalCSIC/13836)
Seismic data segmentation
datsegment1C:
This program permits to segmentate data, e.g., for ambient noise processing, based on rms amplitude variability as introduced in Schimmel et al. (2021). The tar file contains the source code,
a short description and a simple example (Fig 1, Schimmel et al., 2021). My program uses SAC data and runs on linux systems. Just download the tar file and open
it with "tar xvf 20220602-datsegment1C.tar".
Time-frequency dependent polarization
Polfre_s1.66el.tar:
Find back azimuth BAZ(t,f), degree of elliptical polarization DOP_el(t,f) (among others) as used in Schimmel et al. (2011b).
The tar file contains the source codes,
descriptions and 4 simple examples. My programs use SAC data and run on linux systems. Just download the tar file and open
it with "tar xvf Polfre_s1.66el.tar" (Previous version:here).
DOI: 10.20350/digitalCSIC/13840)
Rayleigh wave ellipticity, measurement and inversion
DOP-E:
Determination of Rayleigh wave ellipticity as function of frequency (and BAZ) from seismic noise and event recordings and inversion to constrain the S-wave velocity as described in Berbellini et al. (2019). Rayleigh wave ellipticity measurements are based on Schimmel and Gallart (2004) and Schimmel et al. (2011b). The software works with SAC data format and contains an example.
Time-scale phase weighted stacking code
ts-PWS:
This link takes you to the GitHub site with the very fast and efficient ts-PWS stacking code for processing huge data volumes. This is the same as tf-PWS0 but based on wavelet theory. The design, implementation, performance, etc. have been described in Ventosa et al. (2017) and Schimmel et al. (2017). The software works with SAC & binary data formats.
DOI: 10.20350/digitalCSIC/13846)
Fast and efficient phase cross-correlation (C Programs and examples)
PCC:
This link takes you to the very fast and efficient phase cross-correlation code for processing huge data volumes. The approach has been published as Ventosa et al. (2019) .
DOI: 10.20350/digitalCSIC/13837
Fast and efficient phase cross-correlation (Python routine)
PCC2:
This is a fast and efficient python routine from Luis-Fabian Bonilla (IPGP & IFSTTAR). It computes the phase cross-correlation using the power of 2 to reduce operation complexity by an analytic simplification of the pcc equation. See Ventosa et al. (2019) for the details.
Group velocity determination using phase coherence and resampling strategies
TS_PWS0_UG_1.5:
This link takes you to the code for measuring group velocities in seismic noise correlation studies. The approach has been published in Schimmel et al. (2017) . It employs the phase coherence in the wavelet domain to stack noise cross-correlations and uses resampling strategies to robustly determine group velocities. The example uses the data from Figure 5 of Schimmel et al. (2017) .
P-wave and S-wave velocity model for Brazil BR_tomo.tar.bz2: Velocity models (velocity perturbations) as published in Schimmel et al. (2003). The file can be opened using tar xvfj 2003-MSchi_BR_tomo.tar.bz2. You will find plain text files with the P- and S-wave velocity perturbations, the reference velocity model, and absolute velocities for grid points given by their latitude, longitude and depth. The absolute velocities need to be taken with care, since the inversion provides velocity perturbations and is invariant to constant velocity shifts (see my Fig. 13 in the publication).
Group velocity maps 2021-Nuñez_CR-GroupVelocityMaps.txt and 3-D S-wave velocity model 2021-Nuñez_CR-S-VelocityModel.txt for Costa Rica: Ambient noise fundamental mode Rayleigh wave group velocity maps and corresponding 3-D S-wave velocity model as published in Nuñez et al. (2020). (File formats: Latitude,Longitude,Period,Group Velocity and Latitude,Longitude,Depth,S-wave Velocity. Units are in deg, km, s, km/s. An S-wave velocity NaN indicates that there is no resolution at the corresponding grid point.)
Upper mantle discontinuities beneath Iberia and N-Morocco 2015-Bonatto_Iberia_410-660.tar.gz: Depth of the 410-km and 660-km discontinuities as published in Bonatto et al. (2015). The tar-file can be opened using tar xvf 2015-Bonatto_Iberia_410-660.tar. You will find 3 plain text files with station positions, and depths to the 410-km and 660-km discontinuities as function of bin position. File contents and format are explained in a README.pdf. These tables were used to generate the Figures 1b, 5,6,7,8,9 of Bonatto et al. (2015). See also Bonatto et al. (2013) for further information.
Paleozoic Ebro Basin (Spain) 2018-Romero_EbroBasin.txt: Here you can download Table S1 of Romero and Schimmel (2018) as text file. We use ambient noise autocorrelations to obtain the shallow subsurface reflection response in the Ebro Basin and focus to the Paleozoic basement. The table contains the station positions, two-way travel time of the reflected P-waves and the final discontinuity depths values obtained with our velocity models. Please, see Romero and Schimmel (2018) for further information.
Monitoring 2011 El Hierro, Canary Islands, submarine eruption 2018-Sanchez_ElHierro_volcan.mp4: Movie of scattering cross-section density maps at various lag times as function of time (recorded day). The movie shows the location of the medium changes for the different phases (e.g., 2011 pre-eruption, quiet periods, 2012 pre-intrusions, intrusions). Data analyses and inversions are explained in Sanchez-Pastor et al. (2018).