A User Tomo DD SE Manual

User Manual:

Open the PDF directly: View PDF .
Page Count: 10

Syntax to run the program
Parameters

User’s manual for tomoDD-SE (Regional-Scale DD tomography) for determining event

locations and velocity structure from both absolute and differential data

By Haijiang Zhang* and Clifford H. Thurber

Department of Geoscience

University of Wisconsin-Madison

*Also at School of Earth and Space Science,

University of Science and Technology of China

September, 2015

1. Description

TomoDD is a computer program that realizes the double-difference (DD) seismic

tomography method. DD tomography makes use of both absolute and differential arrival

times to jointly determine event locations and velocity structure. By taking into account

path anomaly biases between event pairs explicitly, DD tomography has the ability to

determine the absolute and relative event locations and velocity structure accurately with

the direct use of the more accurate differential arrival times (from catalog and/or

waveform cross correlation (WCC) data). TomoDD adopts a hierarchical weighting

scheme to combine different data types into one system. Initially, higher weighting is

applied to catalog absolute times to image the velocity structure at a large scale, followed

by applying higher weighting to the catalog differential times and/or WCC data (if

available) in order to refine the event locations and the velocity structure near the source

region. TomoDD is modified from the double-difference location code hypoDD

(Waldhauser 2001). For both methods, please refer to Waldhauser & Ellsworth(2000),

and Zhang & Thurber (2003) for details. The users are strongly recommended to be

familiar with hypoDD before using tomoDD.

TomoDD uses a regular three-dimensional grid to represent the velocity model, the

same as simul2000 algorithm (Thurber and Eberhart-Phillips, 1999). The travel times

between events and stations are calculated using the pseudo-bending ray tracing

algorithm (Um and Thurber, 1987). This version of tomoDD is only applicable to the

local scale tomography problem (<100 km). For the larger scale, please refer to another

computer program tomoFDD that deals properly with the spherical shape of the Earth.

2. Install and syntax

This program has been tested successfully on both Sun/Unix and linux platforms.

Before executing the Makefile (Makefile.gfortran for gfortran and gcc compilers or

Makefile.intel for Intel icc or ifort compilers) to compile and install the program, change

the array dimensions in tomoDD.inc and ray_common.inc according to the solved

problem and computer memory space. You should also choose correct compiling options

for the corresponding compilers. There is a README file that is helpful before

compiling the program.

Syntax to run the program

tomoDD

In the new version (tomoDD-SE), it first outputs some information about the

Software License Agreement before running the program. Here is a screen output

from tomoDD-SE:

Regional-Scale Double-Difference Seismic Tomography (tomoDD-SE)

By running this program, you represent and warrant to WARF that you have read,

understand and agree to the terms of the Agreement enclosed in copyright.txt

and that you have full authority to enter into this Agreement without obtaining

any other approvals.

The control file refers to tomoDD.inp that contains the control parameters for running

the program.

3. Array dimensions in tomoDD.inc and ray_common.inc (in the directory include)

In tomoDD.inc:

It is only necessary to change MAXEVE, MAXSTA, MAXDATA, MAXNODE, and

MAXND to satisfy the solved problem and computer memory space. For other hypoDD

parameters MAXEVE0, MAXDATA0, MAXLAY, MAXCL, tomoDD does not use

them any more and you can leave them unchanged.

MAXEVE: maximum number of events used in the inversion.

MAXSTA: maximum number of stations used in the inversion.

MAXDATA: maximum number of phase data including both absolute and

differential data.

MAXNODE: maximum number of inversion nodes for each ray to sample

(~4*MAXNZ).

MAXND: it is used to control the maximum number of nonzero slowness partial

derivatives (MAXND*MAXDATA) (<4*MAXNZ).

In ray_common.inc:

The following parameters control the number of grid nodes used to represent the

Earth in the three directions.

maxnx---maximum number of nodes in x direction

maxny--- maximum number of nodes in y direction

maxnz--- maximum number of nodes in z direction

mxpari--- maximum number of parameters to invert for.

maxpar--- maximum number of potential parameters that could be included in the

inversion. For tomoDD, mxpari is equal to maxpar. Both of them should be at least equal

to iuses*(maxnz-2)*(maxny-2)*(maxnz-2).

4. Control file (tomoDD-SE.inp)

This file is an interface for the users to control how tomoDD runs, which has a similar

structure to hypoDD.inp, as follows. Sentences staring with a star indicate the

commentaries.

* tomoDD-SE.inp:

*--- input file selection

* cross correlation diff times:

dt.cc

*catalog P diff times:

dt.ct

* event file:

event.dat

* station file:

station.dat

*--- output file selection

* original locations:

tomoDD.loc

* relocations:

tomoDD.reloc

* station information:

tomoDD.sta

* residual information:

tomoDD.res

* source paramater information:

*tomoDD.src

*DWS and velocity structure

tomoDD.vel

*final Vp model

Vp_model.dat

*final Vs model

Vs_model.dat

* catalog absolute data

absolute.dat

*--- data type selection:

* IDAT: 0 = synthetics; 1= cross corr; 2= catalog; 3= cross & cat

* IPHA: 1= P; 2= S; 3= P&S

* DIST:max dist [km] between cluster centroid and station

* IDAT IPHA DIST

2 3 40

*--- event clustering:

* OBSCC: min # of obs/pair for crosstime data (0= no clustering)

* OBSCT: min # of obs/pair for network data (0= no clustering)

* Air_dep: the shallowest depth of the earthquake

* OBSCC OBSCT Air_dep

0 0 -0.0

*--- solution control:

* ISTART: 1 = from single source; 2 = from network sources

* ISOLV: 1 = SVD, 2=lsqr

* NSET: number of sets of iteration with specifications following

* wlat, wlon: the location (latitude and longitude) of the

* coordinate center

* CC_format: the format of dt.cc

* weight1, weight2, weight3: the smoothing parameters of the

* direction of longitude, latitude and depth

* ISTART ISOLV NSET

2 2 4

* iuses iuseq invdel stepl

2 0 0 5

* wlat wlon rota

30.3 103.3 0

* weight1 weight2 weight3 CC_format

40 40 15 1

*--- data weighting and re-weighting:

* NITER: last iteration to used the following weights

* WTCCP, WTCCS: weight cross P, S

* WTCTP, WTCTS: weight catalog P, S

* WRCC, WRCT: residual threshold in sec for cross, catalog data

* WDCC, WDCT: max dist [km] between cross, catalog linked pairs

* WTCD: relative weighting between absolute and differential data

* DAMP: damping (for lsqr only)

* THRES: Scalar used to determine the DWS threshold values

* --- CROSS DATA ----- ----CATALOG DATA ----

* NITER WTCCP WTCCS WRCC WDCC WTCTP WTCTS WRCT WDCT WTCD DAMP JOINT THRES

3 0.01 0.01 -9 -9 0.1 0.08 -9 -9 10 300 1 0.2

3 0.01 0.01 -9 -9 0.1 0.08 8 -9 10 300 1 0.2

3 0.01 0.01 -9 -9 1.0 0.80 6 -9 0.01 250 1 0.2

3 0.01 0.01 -9 -9 1.0 0.80 6 20 0.01 250 1 0.2

3 1 0.8 -9 -9 0.01 0.008 6 20 0.1 200 1 0.2

3 1 0.8 6 -9 0.01 0.008 6 20 0.1 200 1 0.2

*--- event selection:

* CID: cluster to be relocated (0 = all)

* ID: cuspids of event to be relocated (8 per line)

* CID

* ID

Parameters description for file tomoDD.inp

CC_FORMAT--- cross-correlation data format: 1= hypoDD format; 2= tomoDD

format.

WGH1, WGH2, WGH3--- 1st order smoothing constraints applied to slowness

changes in X, Y and Z directions, respectively.

AIR_DEPTH--- The depth above it is defined as air. This is for the purpose of

defining air quakes, which will be removed from inversion.

IUSES---1= invert Vp only; 2=invert both Vp and Vs.

LAT_ORIG, LON_ORIG: user defined coordinate center.

ROTA: coordinate system rotation angles (anticlockwise: -; clockwise: +).

Weighting parameters:

WTCCP, WTCCS: weight cross P, S

WTCTP, WTCTS: weight catalog P, S

WRCC, WRCT: residual threshold in sec for cross, catalog data

WDCC, WDCT: max dist [km] between cross, catalog

WTCD : relative weighting between absolute and differential

catalog data.

Joint-----0 event relocation only

1 simultaneous inversion of event locations and velocity structure

THRES---Derivative Weight Sum (DWS) scalar for both Vp and Vs. The actual DWS

threshold values are THRES times the average P-wave and S-wave DWS

values. If a node has a DWS value less than THRES, this node is fixed

during this inversion.

DAMP--- damping value for LSQR. The damping value is normally chosen to make

the condition number to be around ~60.

5. Input files

5.1 Cross-correlation data file (dt.cc)

This file stores differential time data from waveform cross-correlation techniques.

For CC_format=1 (hypoDD format):

Each event pair is listed by a header line and followed by lines with observations, as

follows,

# ID1, ID2, OTC

STA, DT, WGHT, PHA

…

# ID1, ID2, OTC

STA, DT, WGHT, PHA

…

This file can be obtained using BCSEIS (Bispectrum Cross-correlation package for

SEISmic events) (Du and Thurber, 2004).

For CC_format=2 (tomoDD format):

Each line lists one event pair and their associated observations (it assumes that the

origin times from waveform data are the same as catalog data), as follows,

ID1, ID2, STA, DT, WGHT, PHA

This data format is useful when users arrange the cross-correlation data station by

station.

5.2 Differential catalog data file (dt.ct)

This file has exactly the same format as hypoDD code. Each event pair is listed by a

header line, followed by nobs lines of observations.

#, ID1, ID2

STA, TT1, TT2, WGHT, PHA

…

This file can be produced using the package ph2dt released with hypoDD code

(Waldhauser, 2001).

5.3 Absolute catalog data file (absolute.dat)

This file is new to tomoDD. Each event listed by a header line, followed by nobs of

observations.

#, ID1

STA, TT1, WGHT, PHA

…

The awk file ph2abs.awk can be used to produce the absolute data from the phase file

phase.dat that is used to produce the catalog differential data using program ph2dt.

5.4 Station input file (station.dat)

STA, LAT, LON, DEP

Each line contains station name, latitude, longitude and depth of a given station.

Station depth is in METRES (+ above sea level; - below sea level).

5.5 Event input file (event.dat)

One event per line:

DATE, TIME, LAT, LON, DEP, MAG, EH, EV, RMS, ID, TYPE

The only difference between tomoDD and hypoDD is that event.dat in the former

algorithm contains additional event type information for each event.

TYPE--- 0=earthquake data; 1=shot data; 2=blast data.

5.6 Starting velocity model (MOD).

The file name MUST be MOD. It has the following formats (simul2000):

bld, nx, ny, nz

xn(1),xn(2), ...., xn(nx)

yn(1),yn(2), ...., yn(ny)

zn(1),zn(2), ...., zn(nz)

Vp(1,1,1), Vp(2,1,1),… …, Vp(nx,1,1)

Vp(1,2,1), Vp(2,2,1),… …, Vp(nx,2,1)

… …

Vp(1,ny,1),Vp(2,ny,1),… …, Vp(nx,ny,1)

… …

Vp(1,ny,nz), Vp(2,ny,nz),… …, Vp(nx,ny,nx)

Vp/Vs(1,1,1),Vp/Vs(2,1,1),… …,Vp/Vs(nx,1,1)

Vp/Vs(1,2,1),Vp/Vs(2,2,1),… …,Vp/Vs(nx,2,1)

… …

Vp/Vs(1,ny,1), Vp/Vs(2,ny,1),… …, Vp/Vs(nx,ny,1)

… …

Vp/Vs(1,ny,nz), Vp/Vs(2,ny,nz),… …,Vp/Vs(nx,ny,nx)

Parameters

BLD--- Must be 1 or 0.1. Increment size for ixkms, iykms, and izkms.

NX, NY, and NZ---number of grid nodes in X, Y and Z directions.

XN--- grid node positions in X direction.

YN--- grid node positions in Y direction.

ZN--- grid node positions in Z direction.

Note that xn(1), xn(nx), yn(1), yn(ny), zn(1) and zn(nz) are boundary nodes that must

be large enough to hold all the events and stations.

6. Output files

6.1 Velocity model output (tomoDD.vem, Vp_model.dat and Vs_model.datl)

In the first part of this file, it contains the starting velocity model information.

Then it contains P-wave and S-wave DWS and velocity structure after each

iteration (the same format as MOD). The final velocity models are stored in

Vp_model.dat and Vs_model.dat for P and S waves, respectively.

6.2 Initial hypocenter output (tomoDD.loc)

It has exactly the same format as hypoDD.loc in hypoDD.

One event per line

ID, LAT, LON, DEPTH, X, Y, Z, EX, EY, EZ, YR, MO, DY, HR, MI, SC, MAG, CID

6.3 Relocated hypocenter output (tomoDD.reloc)

It has exactly the same format as hypoDD.reloc in hypoDD.

One event per line

ID, LAT, LON, DEPTH, X, Y, Z, EX, EY, EZ, YR, MO, DY, HR, MI, SC, MAG,

NCCP, NCTP, NCTS, RCC, RCT, CID

6.4 Station residual output (tomoDD.sta)

It has exactly the same format as hpoDD.sta in hypoDD.

One station per line:

STA, LAT, LON, DIST, AZ, NCCP, NCCS, NCTP, NCTS, RCC, RCT, CID

6.5 Data residual output (tomoDD.res)

It has exactly the same format as hypoDD.res in hypoDD.

One observation per line:

STA, DT, ID1, ID2, IDX, WGHT, RES, WT, DIST

6.6 Takeoff angle output (tomoDD.src)

It has similar format as hypoDD.src in hypoDD except that there is one more

takeoff angle for S waves. The takeoff angle is positive if ray path is downward at

the source and negative if the ray path is upward.

For each line, the following parameters are listed:

Event_ID, event_lat, event_lon, station_name, epicental distance, azimuth,

Source_lat, source_lon, P-wave takeoff angle, S-wave takeoff angle

6.7 Run time information output

Run time information is stored tomoDD.log.

7. Other auxiliary programs (in Util)

Some scripts and corresponding notes can be found in the scripts/ folder.

References

J. R. Evans, D. Eberhart-Phillips, and C. H. Thurber, User’s manual for SIMULPS12 for

imaging Vp and Vp/Vs: a derivative of the “Thurber” tomographyic inversion

SIMUL3 for local earthquakes and explosions, U. S. Geological survey, Open

File Report 94-431, 100 pp., 1994.

Um, J., and C. H. Thurber, A fast algorithm for two-point seismic ray tracing, Bull. Seism.

Soc. Am. 77, 972-986, 1987.

F. Waldhauser, hypoDD: a computer program to compute double-difference hypocenter

locations, U. S. Geological Survey, Open File Report 01-113, 25 pp., 2001.

F. Waldhauser, and W. L. Ellsworth, A double-difference earthquake location algorithm:

method an application to the northern Hayward Fault, California, Bull. Seism. Soc.

Am., 80, 1548-1368, 2000.

Thurber, C.H., and D. Eberhart-Phillips, Local earthquake tomography with flexible

gridding, Computers and Geosciences 25, 809-818, 1999.

H. Zhang, and C. H. Thurber, Double-difference tomography: the method and its

application to the Hayward fault, California, Bull. Seism. Soc. Am., 93, 2003.

Zhang, H., and C. Thurber (2006), Development and applications of double-difference

tomography, Pure and Applied Geophys., 163, 373-403, doi:10.1007/s00024-005-

0021-y.

A User Tomo DD SE Manual

Navigation menu

Versions of this User Manual:

Views

Navigation