ANCC

DISCLAIMER

This is a ancc package as delivered to IRIS DMC the University of Colorado by Mikhail Barmine. This is the first release version 1.0 that will provide computation of vertical component of ambient noise cross-correlations.

The distribution includes all sources needed for compiling for the host computer.

University of Colorado does not provide any maintenance or support for public user community, this will be done by IRIS DMC.

This package is distributed as is in the hope that it will be useful, but WITHOUT ANY WARRANTY.

CONTENTS:

1. PACKAGE CONTENTS

2. INSTALLATION

3. SYSTEM REQUIREMENTS

4. COMPUTATION OF AMBIENT NOISE CROSS-CORRELATIONS 3.1 DATA PREPARATION 3.2 DATA PROCESSING 3.2.1 cv_do_CO.csh program (tcsh script) 3.2.1.1 cv_sa_from_seed_holes_RESP program 3.2.1.2 cut_trans_RESP program 3.2.1.3 filter4 and whiten_rej_phamp programs 3.2.1.4 justCOR_mv_dir program 3.2.2 MERGING DATABASES 3.2.3 POSTPROCESSING REFERENCES APPENDIX A

5. PACKAGE CONTENTS

The contents of the package are as follows:

README this file bin contains executable programs and scripts doc contains Data Product Manual include contains include files for the program in src directory SEED contains SEED volumes data archive src contains program source codes TEST1 contains precomputed example test TEST2 directory to run your own installation

1. INSTALLATION

   Use the tar command to extract distribution contents.

   ...> tar xvf ancc-1.0-0.src.tar

This will yield a top level directory named ancc-1.0-0 with an executable, along with other miscellaneous files. Go to ancc-1.0-0/src directory and recompile if necessary all programs. Go to corresponding subdirectory and recompile it with ...> make ...> make install

The resulting binary modules will be installed under ancc-1.0-0/bin directory. In case of problems update Makefile properly. The ancc-1.0-0/bin directory originally includes binary modules compiled by gcc/g77 compilers under RHEL 5.8 (RedHat Enterprise Linux 5.8) Operational System.

The package required installation of the following software:

• rdseed 5.1 - reading SEED volumes;
• sac 104.1 - seismic analysis code;
• fftw 3.2 - libraries for the fast Fourier transformation

rdseed and sac command must be in user's path, and fftw's libraries must be installed into OS for better performance. See an example of run in the directory TEST1 and try your own run in directory TEST2.

2. SYSTEM REQUIREMENTS

   • 64-bit or 32-bit OS, 64-bit is preferable
   • Linux Operation System, currently tested on RHEL 5.x, 32 and 64 bit version
   • 2-core CPU, 2.0 Ghz or more
   • 4 Gb of RAM or more
   • 256 Gb hard disk or more (depends on situation)
   • gcc/g77 compilers
   • Software: rdseed 5.1, sac 101.4 and fftw 3.2

3. COMPUTATION OF AMBIENT NOISE CROSS-CORRELATIONS

The process of evaluating cross-correlations (CCs) consists of three basic steps, namely, data preparation, data processing and data postprocessing described below.

3.1 DATA PREPARATION ================

After choosing the area of investigation and the set of seismic stations, it is necessary to create an archive of continuous waveforms during desired period of time. Usually, it is a couple of months or years. Right now, software works only for vertical components of seismic record (LHZ channel) with sampling step 1 second. The archive consists of daily IRIS SEED volumes including continuous waveforms for all stations in the area of investigation that are operating at that day. SEED volume must include response functions for all waveforms and must be readable by rdseed v5.1 IRIS program. The archive itself is a file tree system organized by the year and months. The root directory, say SEED, includes subdirectory with the years, and each year includes subdirectory with number of months. See an example of archive in SEED directory of the distribution set. It includes only two months of data, Apr 2005 and May 2005. Contents of testing archive is listed also in APPENDIX A. The name of SEED file is form of D.yyyy.ddd.M.D.xxxx.... where yyyy - year; ddd - day from the beginning of year, starting from 1; M - number of month, one or two characters; D - day in month,one or two characters.

The fragment of typical IRIS "BREAKFAST" waveform request is shown below:

 ......
 ......

.LABEL: D.2005.106.4.16 ...... ...... WCN NN 2005 04 16 00 00 00.0 2005 04 17 00 00 00.0 1 LHZ 109C TA 2005 04 16 00 00 00.0 2005 04 17 00 00 00.0 1 LHZ A04A TA 2005 04 16 00 00 00.0 2005 04 17 00 00 00.0 1 LHZ ...... ......

3.2 DATA PROCESSING ===============

When the seismic waveform data archive is ready we may start the data processing. There are two main procedures. The first one provides creating one or more monthly cross-correlation database using tshell script cv_do_CO.csh. The second one provides merging predefined set of monthly cross-correlation databases into single one (script do_merge_cor.sh). The total scheme of getting the final cross-correlation database might be chosen in different ways. For example, at first we do yearly databases by merging monthly databases, and later do final database by merging yearly databases.

3.2.1 cv_do_CO.csh program (tcsh script) ==================================

Script cv_do_CO.csh is the main procedure which organizes work spaces and sequential run of five programs written on gcc/g77: cv_sa_from_seed_holes_RESP, cut_trans_RESP, filter4, whiten_rej_phamp, and justCOR_mv_dir. cv_do_CO.csh is called from the shell command line as:

...> cv_do_CO.csh year b_month e_month

where, year - processing year; b_month - starting month, 1 <= b_month <= 12; e_month - ending month, 1 <= e_month <= 12, b_month <= e_month.

For example, to start test example provided in distribution set, go to TEST2 directory and run it as

...> cd TEST2 ...> cv_do_CO.csh 2005 4 5 >& test.log &

As a result script will create two monthly databases for April 2005 and May 2005.The contents of TEST2 directory should be very close to the precompiled results in TEST1 directory. When cv_do_CO.csh starts it immediately creates the work space work1 and the working directory year/b_month for the program cv_sa_from_seed_holes_RESP. Also, script prepares input data for the cv_sa_from_seed_holes_RESP program, namely: creates year/{b_month}_1 directory and copies data of the first month b_month from archive to year/{b_month}_1 directory, creates event list (references to daily SEED volumes files) in the working directory year/b_month, extracts station information from monthly data into shortcut station list file station.lst and stores it under year/b_month and year/{b_month}_1 directories, starts cv_sa_from_seed_holes_RESP program.

3.2.1.1 cv_sa_from_seed_holes_RESP program ==================================

cv_sa_from_seed_holes_RESP produces from SEED volumes daily waveform segments (events) for all given days and stations as a set of binary SAC files (one SAC file per fixed day and station), and retrieve corresponding response information (ASCII files) in the evalresp compatible format. cv_sa_from_seed_holes_RESP provides the following additional functionalities:

• merge multiple waveform segments into single waveform segment
• analyse possible data gaps and reject data with total gaps exceeding treshold value.
• linearly interpolate gaps
• create and store on a disk auxiliary Reference Table (RT) that keeps events/stations/waveforms parameters and references to waveform locations on a disk.
• analyse and store for further correction in RT possible fraction of waveform time, if sample epoch time is not multiple to the sampling step

Usage

...>  cv_sa_from_seed_holes_RESP LHZ theshold_gap

where LHZ - channel name, fixed value theshold_gap - theshold_gap*100 is maximum allowed data gap in waveforms. Recommended value 0.1

cv_sa_from_seed_holes_RESP must be started in year/b_month directory.

Input data

a) File with the fixed name station.lst . The station.lst file is a plain ASCII file given in a tabular form. The file includes shortcut information about seismic station. Each line consists of four fields separated by one or more spaces: network, sta, lon and lat. Here, network - two character name of a seismic network sta - seismic station name, up to 6 characters lon - geographic longitude in degrees lat - geographic latitude in degrees Format: Unformatted.

Example:

CI TUQ -115.923900 35.435800 CI VES -119.084700 35.840900 IU TUC -110.784700 32.309800 TA 109C -117.105100 32.888900 TA A04A -122.707000 48.719700

b) File with the fixed name input_ev_seed The input_ev_seed file is a plain ASCII file given in a tabular form. The file includes information about location of a SEED volume file for a given year, month and day. The location of a SEED volume is described by two sequential lines.

Line 1: ind, year, month, day, comments ind - fixed text string " PDE", must be placed from the first position in line. The first symbol in line must be space. year - four digits year month - number of the month of the year day - number of the day of the month comments - any text Format: Unformatted All fields must be separated by one or more spaces.

Line 2: path path - path to the SEED volume file. Text must start from the first position in a line.

Example:

PDE 2005 4 2 0000000000000 63.52 -147.44 11 8.50 Ms GS 9C.G F.S. ../4_in/ALL_2005_4_2 PDE 2005 4 3 0000000000000 63.52 -147.44 11 8.50 Ms GS 9C.G F.S. ../4_in/ALL_2005_4_3 PDE 2005 4 4 0000000000000 63.52 -147