FLEXWIN User`s Manual - Computational Infrastructure for
Contents
1. The Licensor disclaims any and all liability as regards the Licensee s use of the name of the Software No warranty is given as regards the existence of prior rights over the name of the Software or as regards the existence of a trademark Article 10 TERMINATION 10 1 In the event of a breach by the Licensee of its obligations hereunder the Licensor may automatically terminate this Agreement thirty 30 days after notice has been sent to the Licensee and has remained ineffective CHAPTER 4 MISCELLANEOUS 33 10 2 A Licensee whose Agreement is terminated shall no longer be authorized to use modify or distribute the Software However any licenses that it may have granted prior to termination of the Agreement shall remain valid subject to their having been granted in compliance with the terms and conditions hereof Article 11 MISCELLANEOUS 11 1 EXCUSABLE EVENTS Neither Party shall be liable for any or all delay or failure to perform the Agreement that may be attributable to an event of force majeure an act of God or an outside cause such as defective functioning or interruptions of the electricity or telecommunications networks network paralysis following a virus attack intervention by government authorities natural disasters water damage earthquakes fire explosions strikes and labor unrest war etc 11 2 Any failure by either Party on one or more occasions to invoke one or more of the provi sions hereof shall under n2. Windowing results for the test data set plotted using the plot_seismos_gnt sh script CHAPTER 2 GETTING STARTED 9 2 6 Output files Most output files are in ascii All file names start with the basename given in the input file for that trace basename obs ascii observed seismogram filtered basename syn ascii synthetic seismogram filtered basename obs_lp sac sac observed seismogram filtered basename syn_lp sac sac synthetic seismogram filtered basename env obs ascii envelope of observed seismogram filtered basename env syn ascii envelope of synthetic seismogram filtered basename win list of windows with theoretical phase arrival times basename win qual list of windows with Tshift CC dInA values basename phases theoretical arrival times of phases basename stalta STA LTA timeseries used to select the windows and the time dependent values of the STA LTA water level the cross correlation limit C Co the time lag limit Arto amplitude ratio limit A ln Ap and the window signal to noise limit ro basename info information on the path and some statistics For more details about the file formats read the write_ subroutines in io_subs f90 2 7 Scripts Several plotting routines plot_ sh are provided in the scripts subdirectory as examples for plotting seismograms measurements and adjoint sources All plotting is done using GMT Generic Mapping Tools These scripts will need to be modified to suit your particular plo
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4. The black line represents the limiting value of h hm Vertical bars represent h hy for each pair of max ima Their position along the horizontal axis is given by the time separation AT between the maxima of each pair The color of the bar is given by the color of the seed maximum corresponding to hm Bars whose height exceeds the line represent windows to be rejected c The windows that have been rejected by this criterion are indicated by black crosses CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 17 Figure 3 3 The selection of the best non overlapping window combinations Each grey box represents a distinct group of windows Non overlapping subsets of windows are shown on separate lines Only one line from within each group will be chosen the one corresponding to the highest weighted score The resulting optimal set of data windows is shown by thick arrows azimuth backazimuth dist deg dist km Calculated from the event and station loca tions above kstnm knetwk kcmpnm Station name network name component name read from the ob served seismogram num phases ph names ph times Number names and arrival times of standard seismic phases calculated through IASPEI91 using the event depth and epicentral distance The set_up_criteria_arrays subroutine first sets up non time modulated versions of the time dependent parameters using a simple loop over time do i 1 npts time b
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6. i 1 dt DLNA_LIMIT i DLNA_BASE CC_LIMIT i CC_BASE TSHIFT_LIMIT i TSHIFT_BASE CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 18 STALTA_W_LEVEL i STALTA_BASE S2N_LIMIT i WINDOW_AMP_BASE enddo It is then up to the user to modulate these values for the specific problem at hand For exam ple should the user want to discourage the algorithm from picking windows beyond the end of the first surface wave train R1 the following lines should be added to the user_functions f 90 file to raise the water level on the STA LTA waveform by a factor of ten Set approximate end of rayleigh wave arrival R_vel 3 2 R_time dist_km R_vel modulate criteria in time do i 1 npts time b i 1 dt if time gt R_time then STALTA_W_LEVEL i STALTA_BASE 10 0 endif enddo Should the user want the algorithm to be less stringent in its requirements for the cross correlation fit for the surface wave portion of the seismograms and allow a greater travel time lag for deeper events the required lines could be Set approximate end of rayleigh wave arrival R_vel 3 2 R_time dist_km R_vel Set approximate start of love wave arrival Q_vel 4 2 Q_time dist_km Q_vel modulate criteria in time do i 1 npts time b i 1 dt if we are in the surface wave times then make the cross correlation criterion less severe if time gt Q_time and time lt R_time then CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 19 CC_LIMIT i 0 9 CC_LIMIT
7. portions of the waveform that are dominated by noise FLEXWIN selects time windows on the synthetic seismogram within which the waveform contains a distinct energy arrival then requires an adequate correspondence between observed and synthetic waveforms within these windows There is no restriction on the type of simulation used to generate the synthetics Realistic Earth models and more complete wave propagation theories yield waveforms that are more similar to the observed seismograms and thereby promote the selection of measurement windows covering more of the available data The input seismograms can be measures of displacement velocity or acceleration There is no requirement for horizontal signals to be rotated into radial and transverse directions FLEXWIN is a configurable data selection process that can be adapted to different tomo graphic scenarios by tuning a handful of parameters Although the algorithm was designed for use in 3D 3D adjoint tomography its inherent flexibility should make it useful in many data selection applications For a detailed introduction to FLEXWIN as applied to seismic tomography please consult Maggi et al 2009 If you use FLEXWIN for your own research please cite Maggi et al 2009 Chapter 2 Getting started Here is where you find basic information for obtaining and installing the FLEXWIN package For details of how to tune the algorithm to your seismograms see chapter 3 2 1 Sy
8. using gfortran version 4 1 2 To check your version type gfortran version Important note All the code is compiled with the m32 option which makes 32bit binaries This option is currently required to enable compatibility with SAC Future versions of the SAC distribution may no longer require this compatibility flag Steps to compile the flexwin package 1 Compile libtau a and create iasp91 hed and iasp91 tbl In the flexwin ttimes_mod directory type make f make gfortran This will compile libtau a and two pro grams remodl and setbrn The makefile will also run remodl and setbrn to create the iasp91 hedand iasp91 tbl files You should then type make f make gfortran install to install the iasp91 files 2 Compile flexwin Edit the make_gfortran file in the flexwin root directory to ensure the SACLIBDIR environment variable points to the location of your SAC libraries by default SACHOME 1ib Then type make f make_gfortran You should end up with the flexwin executable The program requires the iasp91 hed and CHAPTER 2 GETTING STARTED 7 iasp91 tb1 files or symbolic links to them to be present in the directory from which the code is launched 2 4 Running the Test case You should test your compiled code on the test_data dataset provided In the flexwin test_data directory type flexwin lt input test The results of your run will be found in the MEASURE subdirectory and should match those found in the MEASURE o
9. A In Aref and A ln Ap t These parameters window signal to noise ratio normalized cross correlation value between observed and synthetic seismograms cross correlation time lag and amplitude ratio control the degree of well behavedness of the data within accepted windows The user first sets constant values for these four parameters then adds a time dependence if required Considerations that should be taken into account include the quality of the Earth model used to calculate the synthetic seismograms the frequency range the dispersed nature of certain arrivals e g for t corresponding to the group velocities of surface waves reduce CCo t and a priori preferences for picking certain small amplitude seismic phases e g for t close to the expected arrival for Pjg reduce ro t ATref and A In Aref should be set to zero at first and only reset if the synthetics contain a systematic bias in traveltimes or amplitudes co 4 These parameters control the process by which the suite of all possible data windows is pared down using criteria on the shape of the STA LTA E t waveform alone We suggest the user start by setting these values to those used in our global example see Table 3 2 Subsequent minimal tuning should be performed by running the algorithm on a subset of the data and closely examining the lists of windows rejected at each stage to make sure the user agrees with the choices made by the algorithm WCC Wien and Wnw
10. FLEXWIN User s Manual Alessia Maggi Seismograms STA LTA Envelopes 0 770 1540 2310 3080 3850 4620 5390 6160 6930 Contents 1 Introduction 2 Getting started 2 1 System requirements 2 2 Obtaiming the code span Doe fe DI e ds 2 35 Comipilationi rela tto e ig E AA pia 2 4 Running the Test case 20 Running PUR X WIN isla PE pel kee en BED 2 6 Oiit put les gt is secre ok eS ae Dare ia SBOE AS SOG ee Dan AE le Bese ae Bee Daf SCTIPts A Se eae doves dy ete ee WO ee ae aka A a moat e de 2 8 Pre processing suggestions 2 o 3 Tuning FLEX WIN for your seismograms 3 1 User parameters iii Aik aw ea RZ e 3 2 Time dependence of user parameters a 10 11 12 14 CONTENTS 3 2 1 Examples of user functions 2 2 0 0 e 3 2 2 Time intervals for signal to noise calculations 3 3 Tuning considerations 02 ee 4 Miscellaneous 4 1 Bug reports and suggestions for improvements 4 2 Notes and Acknowledgments 0 000000 eee ee eee 4 3 License 19 22 23 25 25 25 26 Chapter 1 Introduction The FLEXWIN software package automates the time window selection problem for seismolo gists It operates on pairs of observed and synthetic single component seismograms defining windows that cover as much of a given seismogram as possible while avoiding
11. and the thick horizontal dashed line its water level wg t Local maxima are indicated by alternating red and blue dots windows are indicated by two headed horizontal arrows The time of the local maximum used as the window seed ty is denoted by the position of the dot Only windows for the fourth local maximum are shown b Rejection of candidate windows based on the amplitude of the local minima The two deep local minima indicated by the grey arrows form virtual barriers All candidate windows that cross these barriers are rejected c Rejection of candidate windows based on the prominence of the seed maximum The local maxima indicated by the grey arrows are too low compared to the local minima adjacent to them All windows that have these local maxima as their seed are rejected black crosses over the window segments below the time series d Shortening of long coda windows The grey bar indicates the maximum coda duration cato Note that after the rejection based on prominence represented in c and before shortening of long coda windows represented in d the algorithm rejects candidate windows based on the separation of distinct phases a process that is illustrated in Figure 3 2 CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 16 h hM Figure 3 2 Rejection of candidate windows based on the separation of distinct phases a Heights of pairs of local maxima above their intervening minimum b
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13. d by the 1 D IASPEI91 model Kennett and Engdahl 1991 and tp indicates the end of the surface wave time window For the 24 120 s data we consider the waveform CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 21 between the start of the P wave to the end of the surface wave We therefore modulate wg t as follows 10wg t lt tp we t wg tp lt t lt tri 3 6 10wg t gt tp For the 6 30 s data the fit between the synthetic and observed surface waves is expected to be poor as the 3D model used to calculate the synthetics cannot produce the required complexity We therefore want to concentrate on body wave arrivals only and avoid surface wave windows altogether by modulating wz t as follows 10wg t lt tp we t we tp St ts 3 7 10wg t gt ts We use constant values of ro t ro CCo t CCo and A In Ao t A ln Ay for both period ranges In order to allow greater flexibility in cross correlation time lag Ar for intermediate depth and deep earthquakes we use 0 08tp h lt 70 km Aro t lt max 0 05tp 1 479 70 km lt h lt 300 km 3 8 max 0 05tp 1 770 h gt 300 km Southern California scenario In the following tp and ts denote the start of the time windows for the crustal P wave and the crustal S wave computed from a 1D layered model appropriate to Southern California Wald et al 1995 The start and end times for the surface wave time window tro and tri as well as the criteria for the time
14. d on the source and station characteristics which may be heterogeneous in any given data set these filter periods can be modified dynamically by constructing an appropriate user function e g if station is in list of stations with instrument X then reset TO and T1 to new values rpa In setting the signal to noise ratios for the entire seismogram the user is applying a simple quality control on the data Note that these criteria are applied after filtering No windows will be defined on data that fail this quality control wg t For a constant signal the short term average long term average ratio E t converges to a constant value when the length of the time series is greater than the effective averaging length of the long term average This value is 0 08 for the short term average long term average ratio used in FLEXWIN it has a small dependence on T which can be ignored in most applications We suggest the user start with a constant level for wg t equal to this convergence value The time dependence of w t should then be adjusted to exclude those portions of the waveform the user is not interested in by raising wg t e g to exclude the fundamental mode surface wave if t gt fundamental mode surface wave arrival time then set wg t 1 We suggest finer adjustments to wg t be made after r0 t CCo t ATo t and A ln Ao t have been configured CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 24 rolt CCo t Ater Aro t
15. dex 16 France Institut National de Recherche en Informatique et en Automatique INRIA a public scien tific and technological establishment having its principal place of business at Domaine de Voluceau Rocquencourt BP 105 78153 Le Chesnay cedex France Preamble The purpose of this Free Software license agreement is to grant users the right to modify and redistribute the software governed by this license within the framework of an open source distribution model The exercising of these rights is conditional upon certain obligations for users so as to preserve this status for all subsequent redistributions CeCILL stands for Ce a C nrs I nria L ogiciel L ibre Version 2 0 dated 2006 09 05 CHAPTER 4 MISCELLANEOUS 27 In consideration of access to the source code and the rights to copy modify and redistribute granted by the license users are provided only with a limited warranty and the software s author the holder of the economic rights and the successive licensors only have limited liability In this respect the risks associated with loading using modifying and or developing or re producing the software by the user are brought to the user s attention given its Free Software status which may make it complicated to use with the result that its use is reserved for devel opers and experienced professionals having in depth computer knowledge Users are therefore encouraged to load and test the suitability of the
16. dows is based on the details of the waveforms and not on information from 1D Earth models CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 20 Global scenario In the following h indicates earthquake depth tg indicates the approximate start of the Love wave predicted by a group wave speed of 4 2 km s and tg indicates the approximate end of the Rayleigh wave predicted by a group wave speed of 3 2 km s71 In order to reduce the number of windows picked beyond R1 and to ensure that those selected beyond R1 are a very good match to the synthetic waveform we raise the water level on the STA LTA waveform and impose stricter criteria on the signal to noise ratio and the waveform similarity after the approximate end of the surface wave arrivals We allow greater flexibility in cross correlation time lag Ar for intermediate depth and deep earthquakes We lower the cross correlation value criterion for surface waves in order to retain windows with a slight mismatch in dispersion characteristics We therefore use the following time modulations wet lt tr 2wgt gt tr ro t lt tr l0ro t gt tp CCo t lt tpr CCo t 4 0 9CCo to lt t lt tpr 3 3 0 95 t gt ta t lt tR di O ea 3 tota N di 3 4 1 470 70 km lt h lt 300 km 1 77 h gt 300 km A ln Ao t lt tR AlnAo 3 t gt tr Aln Ao t Japan scenario In the following tp and tg denote the start of the time windows for P and S waves as predicte
17. e signal does not have to coincide with the end of the noise CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 23 3 3 Tuning considerations FLEXWIN is not a black box application and should not be applied blindly to any given dataset or tomographic scenario The data windowing required by any given problem will differ depending on the inversion method the scale of the problem local regional global the quality of the data set the quality of the model and the accuracy of the method used to calculate the synthetic seismograms The user must configure and tune the algorithm for the given problem Here we discuss general considerations the user should bear in mind We suggest the following as a practical starting sequence for tuning the algorithm Keep in mind that this process may need to be repeated and refined several times before converging on the optimal set of parameters for a given problem and data set To 1 In setting the corner periods of the bandpass filter the user is deciding on the frequency content of the information to be used in the tomographic problem Values of these corner periods should reflect the information content of the data the quality of the Earth model and the accuracy of the simulation used to generate the synthetic seismogram The frequency content in the data depends on the spectral characteristics of the source on the instrument responses and on the attenuation characteristics of the medium As T depen
18. ement each with a separate number These subsequent versions may address new issues encountered by Free Software 12 3 Any Software distributed under a given version of the Agreement may only be subse quently distributed under the same version of the Agreement or a subsequent version subject to the provisions of Article 5 3 4 CHAPTER 4 MISCELLANEOUS 34 Article 13 GOVERNING LAW AND JURISDICTION 13 1 The Agreement is governed by French law The Parties agree to endeavor to seek an amicable solution to any disagreements or disputes that may arise during the performance of the Agreement 13 2 Failing an amicable solution within two 2 months as from their occurrence and unless emergency proceedings are necessary the disagreements or disputes shall be referred to the Paris Courts having jurisdiction by the more diligent Party Bibliography B L N Kennett and E R Engdahl Traveltimes for global earthquake location and phase identification Geophys J Int 105 429 465 1991 D Komatitsch Q Liu J Tromp P S ss C Stidham and Shaw J H Simulations of ground motion in the Los Angeles basin based upon the spectral element method B Seismol Soc Am 94 187 206 2004 A Maggi C Tape M Chen D Chao and J Tromp An automated time window selection algorithm for seismic tomography Geophys J Int 178 257 281 2009 L A Wald L K Hutton and D D Given The Southern California Network Bulletin 1990 1993 sum
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20. h emergent starts and or codas WCC Wien Wnwin for selection of best non overlapping window combination Table 3 1 Overview of standard tuning parameters and of fine tuning parameters Values are defined in a parameter file and the time dependence of those that depend on time is described by user defined functions 3 1 User parameters The main user parameters in the PAR_FILE are WIN_MIN_ PERIOD Corresponds to Ty in Table 3 1 and is the short wavelength cut off for the band pass filter applied to the raw synthetic and observed seismograms WIN_MAX_PERIOD Corresponds to T in Table 3 1 and is the long wavelength cut off for the band pass filter applied to the raw synthetic and observed seismograms SNR_INTEGRATE_BASE Corresponds to rp in Table 3 1 and is the minimum signal to noise ratio on the power of the observed seismogram for windowing to continue SNR_MAX BASE Corresponds to rx in Table 3 1 and is the minimum signal to noise ratio on the modulus of the observed seismogram for windowing to continue WINDOW_S2N_BASE Corresponds to ro in Table 3 1 and is the minimum signal to noise ratio for a window on the observed seismogram to be acceptable STALTA BASE Corresponds to wg in Table 3 1 and is the water level to be applied to the synthetic short term long term average waveform in order to generate candidate time windows See Figure 3 1a CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 13 CC_BASE Corresponds
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22. i endif modulate criteria according to event depth if an intermediate depth event if evdp ge 70 and evdp 1t 300 then TSHIFT_LIMIT i TSHIFT_BASE 1 4 if a deep event elseif evdp ge 300 then TSHIFT_LIMIT i TSHIFT_BASE 1 7 endif enddo The above examples illustrate the power of the user_functions 90 file The user can choose to include exclude any portion of the seismogram and to make the rejection criteria for windows more or less stringent on any other portion of the seismogram All the seismogram dependent variables whose values are known when the set_up_criteria_arrays subroutine is executed may be used to inform these choices leading to an infinite number of windowing possibilities The careful user will use knowledge of the properties of the observed data set the limitations of the synthetic waveforms and the final use to which the selected windows will be put in order to tailor the subroutine to the needs of each study For a given set of data and synthetics the PAR_FILE and user_functions f90 files uniquely determine the windowing results 3 2 1 Examples of user functions Here we present the time dependencies of tuning parameters used for three tomographic scenarios Maggi et al 2009 global Japan and southern California In each example we use predicted arrival times derived from 1D Earth models to help modulate certain parameters Note however that the actual selection of individual win
23. in These parameters control the overlap resolution stage of the algorithm Values of wcc Wien Wnwin 1 should be reasonable for most applications The objective of the tuning process summarized here should be to maximize the selection of windows around desirable features in the seismogram while minimizing the selection of unde sirable features Of course the desirability or undesirability of a given feature is subjective and it depends on how the user subsequently intends to use the information contained within the data windows Chapter 4 Miscellaneous 4 1 Bug reports and suggestions for improvements To report bugs or suggest improvements to the code please send an email to the CIG Compu tational Seismology Mailing List cig seismo geodynamics org or Alessia Maggi alessia unistra fr and or use our online bug tracking system Roundup www geodynamics org roundup 4 2 Notes and Acknowledgments The main developers of the FLEXWIN source code are Alessia Maggi and Carl Tape The following individuals listed in alphabetical order have also contributed to the development of the source code Daniel Chao Min Chen Vala Hjorleifsdottir Qinya Liu Jeroen Tromp The following individuals listed in alphabetical order contributed to this manual Sue Kientz Alessia Maggi Carl Tape The FLEXWIN code makes use of filtering and enveloping algorithms that are part of SAC Seismic Analysis Code Lawerence Livermore National Lab
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26. mary Seismol Res Lett 66 9 19 1995 35
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28. nds to C3 in Table 3 1 and is expressed as a multiple of T It regulates the acceptable time separation between local maxima in a given window on the STA LTA waveform See Figure 3 2 C_4a Corresponds to C4g in Table 3 1 and is expressed as a multiple of T It limits the length of a window before its first local maximum in STA LTA C_4b Corresponds to C4 in Table 3 1 and is expressed as a multiple of Tp It limits the length of a window beyond its last local maximum in STA LTA See Figure 3 1d WEIGHT_AVERAGE_CC Corresponds to wcc in Table 3 1 and is the weight given to the average cross correlation value in the process of resolving window overlaps See Figure 3 3 WEIGHT_SPACE_COVERAGE Corresponds to Wien in Table 3 1 and is the weight given to the time span covered by windows in the process of resolving window overlaps CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 14 Global Japan S California Toi 50 150 24 120 6 30 6 30 3 30 2 30 TP A 35 30 35 30 3 5 3 0 3 0 2 5 2 5 3 5 2 5 3 5 ro 2 5 1 5 3 0 3 0 4 0 4 0 WE 0 08 0 11 0 12 0 18 0 11 0 07 CCo 0 85 0 70 0 73 0 71 0 80 0 85 AT 15 12 0 3 0 8 0 4 0 3 0 Aln Ao 1 0 1 0 1 5 1 5 1 0 1 0 ATret 0 0 0 0 0 0 4 0 2 0 1 0 A ln Aref 0 0 0 0 0 0 0 0 0 0 0 0 co 0 7 0 7 0 7 0 7 1 3 1 0 CI 4 0 3 0 3 0 2 0 4 0 5 0 Ca 0 3 0 0 0 6 0 0 0 0 0 0 C3a b 10 20 1 0 2 0 1 0 20 80 20 4 0 2 5 4 0 2 5 Chab 3 0 10 0 3 0 25 0 3 0 12 0 2 5 12 0 2 0 6 0 2 0 6 0 WCC Wen W
29. ntributors on the Software and to take where applicable vis vis its staff any and all measures required to ensure respect of said intellectual property rights of the Holder and or Contributors Article 7 RELATED SERVICES 7 1 Under no circumstances shall the Agreement oblige the Licensor to provide technical assistance or maintenance services for the Software However the Licensor is entitled to offer this type of services The terms and conditions of such technical assistance and or such maintenance shall be set forth in a separate instrument Only the Licensor offering said maintenance and or technical assistance services shall incur liability therefor 7 2 Similarly any Licensor is entitled to offer to its licensees under its sole responsibility a warranty that shall only be binding upon itself for the redistribution of the Software and or the Modified Software under terms and conditions that it is free to decide Said warranty and the financial terms and conditions of its application shall be subject of a separate instrument executed between the Licensor and the Licensee Article 8 LIABILITY 8 1 Subject to the provisions of Article 8 2 the Licensee shall be entitled to claim compen sation for any direct loss it may have suffered from the Software as a result of a fault on the part of the relevant Licensor subject to providing evidence thereof 8 2 The Licensor s liability is limited to the commitments made under th
30. nwin 1 1 1 1 1 1 1 1 1 0 5 1 0 0 7 0 70 0 25 0 05 1 1 1 Table 3 2 Values of standard and fine tuning parameters for the three seismological scenarios discussed Maggi et al 2009 This table is identical to Table 3 of that study WEIGHT_N_WINDOWS Corresponds to Wnwin in Table 3 1 and is the weight given to the total number of windows in the process of resolving window overlaps 3 2 Time dependence of user parameters A subset of the FLEXWIN parameters from Table 3 1 are time dependent where time is measured along the seismogram This feature enables the user to exercise fine control of the windowing algorithm The user can modulate the time dependence of these parameters by editing the set_up_criteria_arrays subroutine in the user_functions f90 file This subroutine is called after the seismograms have been read in and the following variables have been set npts dt b Number of points time step time of first point with respect to the reference time of both seismograms The observed and synthetic seismograms should have iden tical values of these three quantities evla evlo evdp stla stlo Event latitude event longitude event depth km station latitude station longitude read from the observed seismogram CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 15 Figure 3 1 a Window creation process The thick black line represents the STA LTA waveform E t
31. o circumstances be interpreted as being a waiver by the interested Party of its right to invoke said provision s subsequently 11 3 The Agreement cancels and replaces any or all previous agreements whether written or oral between the Parties and having the same purpose and constitutes the entirety of the agreement between said Parties concerning said purpose No supplement or modification to the terms and conditions hereof shall be effective as between the Parties unless it is made in writing and signed by their duly authorized representatives 11 4 In the event that one or more of the provisions hereof were to conflict with a current or future applicable act or legislative text said act or legislative text shall prevail and the Parties shall make the necessary amendments so as to comply with said act or legislative text All other provisions shall remain effective Similarly invalidity of a provision of the Agreement for any reason whatsoever shall not cause the Agreement as a whole to be invalid 11 5 LANGUAGE The Agreement is drafted in both French and English and both versions are deemed authentic Article 12 NEW VERSIONS OF THE AGREEMENT 12 1 Any person is authorized to duplicate and distribute copies of this Agreement 12 2 So as to ensure coherence the wording of this Agreement is protected and may only be modified by the authors of the License who reserve the right to periodically publish updates or new versions of the Agre
32. oratory provided for free to IRIS members We thank Brian Savage for adding interfaces to these algorithms in recent SAC distributions We acknowledge support by the National Science Foundation under grant EAR 0711177 Daniel Chao received additional support from a California Institute of Technology Summer 25 CHAPTER 4 MISCELLANEOUS 26 Undergraduate Reseach Fellowship 4 3 License CeCILL FREE SOFTWARE LICENSE AGREEMENT Notice This Agreement is a Free Software license agreement that is the result of discussions between its authors in order to ensure compliance with the two main principles guiding its drafting e firstly compliance with the principles governing the distribution of Free Software access to source code broad rights granted to users e secondly the election of a governing law French law with which it is conformant both as regards the law of torts and intellectual property law and the protection that it offers to both authors and holders of the economic rights over software The authors of the CeCILL license are Commissariat a l Energie Atomique CEA a public scientific technical and industrial re search establishment having its principal place of business at 25 rue Leblanc immeuble Le Ponant D 75015 Paris France Centre National de la Recherche Scientifique CNRS a public scientific and technological establishment having its principal place of business at 3 rue Michel Ange 75794 Paris ce
33. rig subdirectory You can also test the basic plotting script by running plot_seismos_gmt sh MEASURE ABKT II LHZ whose output will be MEASURE ABKT II LHZ seis eps file Your result should be identical to what is shown in Figure 2 1 2 5 Running FLEXWIN In general flexwin is run as follows flexwin lt input where the input file is formatted as follows 327 RAW_DATA 9627721 CI ADO BHR sac d fil SYNTH ADO CI BHR new fil MEASURE ADO CI BHR RAW_DATA 9627721 CI ADO BHT sac d fil SYNTH ADO CI BHT new fil MEASURE ADO CI BHT RAW_DATA 9627721 CI ADO BHZ sac d fil SYNTH ADO CI BHZ new fil MEASURE ADO CI BHZ i e the number of traces to be measured followed by in order the path to the raw data sac file the path to the synthetic sac file and the path and basename for the many output files for that trace CHAPTER 2 GETTING STARTED 8 ABKT I LHZ ghsestees OS GPS i S meU it Seismograms 0 96 dT 3 00 dA 0 08 CC 0 97 dT 0 00 5 00 0 16 0 98 5 00 Il i i i Boge ERD Rey 0 770 1540 2310 3080 3850 4620 5390 6160 6930 Time s STA LTA 0 770 1540 2310 3080 3850 4620 5390 6160 6930 Time s Envelopes A NA DE AA ARAN IAA nN 0 770 1540 2310 3080 3850 4620 5390 6160 6930 no BEER Time s 2008 May 22 15 40 42 MEASURE 050295B 050295B 050 150 ABKT II LHZ Figure 2 1
34. se positives windows around undesirable fea tures of the seismogram are minimized and true positives window around desirable features are maximized The choice of what makes an adequate set of windows remains subjective as it depends strongly on the quality of the input model the quality of the data and the region of the Earth that the tomographic inversion aims to constrain The base values of the various parameters are set in the PAR_FILE which is read at run time Examples of base parameter values for the three tomographic scenarios discussed by Maggi et al 2009 can be found in Table 3 2 The functional forms of the time dependent parameters may be adjusted by modifying user_parameters 90 see next section and re compiling the code 11 CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 12 Standard tuning parameters Toi bandpass filter corner periods rTPA signal to noise ratios for whole waveform ro t signal to noise ratios single windows we t water level on short term long term ratio CCo t acceptance level for normalized cross correlation A t acceptance level for time lag A ln Ao t acceptance level for amplitude ratio ANT reg reference time lag Aln Aver reference amplitude ratio Fine tuning parameters co for rejection of internal minima CI for rejection of short windows C2 for rejection of un prominent windows C3a b for rejection of multiple distinct arrivals Chas for curtailing of windows wit
35. shifts Azo t are derived from formulas in Komatitsch et al 2004 The source receiver distance in km is denoted by A CHAPTER 3 TUNING FLEXWIN FOR YOUR SEISMOGRAMS 22 For the 6 30 s and 3 30 s data we use constant values of ro t ro CCo t CCo Ato t Aro and Aln Ao t Aln Ap We exclude any arrivals before the P wave and after the Rayleigh wave This is achieved by the box car function for wz t 10wg t lt tp we t wg tp lt t lt tri 3 9 l0wg t gt tpi For the 2 30 s data we avoid selecting surface wave arrivals as the 3D model used to calculate the synthetics cannot produce the required complexity The water level criteria then becomes 10wg t lt tp we t que tp lt t lt ts 3 10 10wg t gt tg 3 2 2 Time intervals for signal to noise calculations If the parameter DATA_QUALITY true in the PAR_FILE then the user_functions f90 file requires the specification of four times that define the noise and signal time intervals For example the default user_functions f90 file contains these lines these values will be used for signal2noise calculations if DATA_QUALITY then noise_start b noise_end ph_times 1 WIN_MAX_PERIOD signal_start noise_end signal_end b npts 1 dt endif The use of all four variables allows provides the flexibility of choosing these time intervals For example the start of the noise does not need to be the beginning of the seismogram Or the start of th
36. software as regards their requirements in conditions enabling the security of their systems and or data to be ensured and more gener ally to use and operate it in the same conditions of security This Agreement may be freely reproduced and published provided it is not altered and that no provisions are either added or removed herefrom This Agreement may apply to any or all software for which the holder of the economic rights decides to submit the use thereof to its provisions Article 1 DEFINITIONS For the purpose of this Agreement when the following expressions commence with a capital letter they shall have the following meaning Agreement means this license agreement and its possible subsequent versions and annexes Software means the software in its Object Code and or Source Code form and where applicable its documentation as is when the Licensee accepts the Agreement Initial Software means the Software in its Source Code and possibly its Object Code form and where applicable its documentation as is when it is first distributed under the terms and conditions of the Agreement Modified Software means the Software modified by at least one Contribution Source Code means all the Software s instructions and program lines to which access is required so as to modify the Software Object Code means the binary files originating from the compilation of the Source Code Holder means the holder s of the economi
37. stem requirements In order to install and run FLEX WIN requires e UNIX operating system Linux Solaris MacOS e GNU make e a fortran compiler gfortran ifort etc e other packages SAC Seismic Analysis Code available from IRIS GMT Generic Mapping Tools for the plotting scripts FLEXWIN requires the following libraries external to the package in order to compile and run libsacio a and libsac a Both libraries are distributed by IRIS as part of the SAC package version 101 2 and above The IRIS download site as of 30 March 2009 is here http www iris edu software sac sac request htm To check your version type sac CHAPTER 2 GETTING STARTED 6 2 2 Obtaining the code The code is available as a gzipped tarball from CIG Computational Infrastructure for Geo dynamics http www geodynamics org The tarball is unpacked by typing tar xvzf flexwin tgz The package contains the flexwin code and documentation as well as a set of test data examples of user files for different scenarios and a set of utility scripts that may be useful for running flexwin on large datasets 2 3 Compilation If your compiler of choice is gfortran then you should be able to use the make_gfortran makefiles with only minor modifications notably you may need to change the search path for the libsacio a library If you prefer another compiler you should modify the OPT and FC lines in the makefiles accordingly We tested the code
38. to CC in Table 3 1 and is the minimum normalized cross correlation value between synthetic and observed seismogram for a window to be acceptable TSHIFT_BASE Corresponds to Ary in Table 3 1 and is the maximum cross correlation lag in seconds between synthetic and observed seismogram for a window to be acceptable DLNA_BASE Corresponds to A In Ag in Table 3 1 and is the maximum amplitude ratio A ln A or AA A between synthetic and observed seismogram for a window to be acceptable TSHIFT_REFERENCE Corresponds to A7yef in Table 3 1 and allows for a systematic traveltime bias in the synthetics DLNA_REFERENCE Corresponds to A ln Ayer in Table 3 1 and allows for a systematic amplitude bias in the synthetics C_0 Corresponds to Co in Table 3 1 and is expressed as a multiple of wg No window may contain a local minimum in its STA LTA waveform that falls below the local value of Cowg See Figure 3 1b C_1 Corresponds to Ci in Table 3 1 and is expressed as a multiple of Tg No window may be shorter than C170 C_2 Corresponds to Ca in Table 3 1 and is expressed as a multiple of we A window whose seed maximum on the STA LTA waveform rises less than Cowg above either of its adjacent minima is rejected See Figure 3 1c C_3a Corresponds to Csa in Table 3 1 and is expressed as a fraction It regulates the accept able height ratio between local maxima in a given window on the STA LTA waveform See Figure 3 2 C_3b Correspo
39. tting needs The script extract_event_windowing stats sh extracts statistical information on the win dow selection process on the measurements Again you can use use this script as a template for your own information extraction needs CHAPTER 2 GETTING STARTED 10 2 8 Pre processing suggestions Pre processing is a subtle procedure that can affect the selection of windows Here we list some suggestions for pre processing 1 Interpolate raw data and raw synthetics using the same time step 2 Cut the data and synthetic seismograms based on the data record If the data record starts before the synthetic record which is common for local earthquakes then consider padding zeros before the synthetic record information prior to the origin time and P arrival is useful in assessing the signal to noise ratio in the observed records 3 Bandpass both the data and synthetics over the desired period range rather than doing this within FLEXWIN thereby limiting the number of filtering operations However for initial determination of the bandpass range of interest it is simpler to experiment using the FLEXWIN parameters WIN_MIN_PERIOD and WIN_MAX_PERIOD Chapter 3 Tuning FLEX WIN for your seismograms FLEXWIN is adapted to your specific problem by modifying the values of the parameters in Table 3 1 and the functional form of those parameters that are time dependent We consider the algorithm to be correctly adapted when fal
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