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https://github.com/yvonnefroehlich/splitlab-temporalalignment

Relative temporal alignment of seismic traces in SplitLab
https://github.com/yvonnefroehlich/splitlab-temporalalignment
anisotropy matlab seismology shear-wave-splitting splitlab stacksplit
Last synced: about 1 month ago
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Relative temporal alignment of seismic traces in SplitLab
Host: GitHub
URL: https://github.com/yvonnefroehlich/splitlab-temporalalignment
Owner: yvonnefroehlich
License: gpl-3.0
Created: 2021-11-14T14:42:19.000Z (about 3 years ago)
Default Branch: main
Last Pushed: 2024-09-17T21:14:55.000Z (4 months ago)
Last Synced: 2024-09-18T10:16:48.540Z (4 months ago)
Topics: anisotropy, matlab, seismology, shear-wave-splitting, splitlab, stacksplit
Language: MATLAB
Homepage:
Size: 3.78 MB
Stars: 2
Watchers: 1
Forks: 0
Open Issues: 0
Metadata Files:
- Readme: README.md
- Changelog: changelog.md
- License: LICENSE
Awesome Lists containing this project

README

        # Temporal Alignment of Seismic Traces in _SplitLab_ [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.5805029.svg)](https://doi.org/10.5281/zenodo.5805029)

This material addresses an error source in the code of the MATLAB based shear wave splitting software package

_SplitLab_ ([**_Wüstefeld et al., 2008_**](https://doi.org/10.1016/j.cageo.2007.08.002)). The error causes a

wrong temporal alignment of the single traces (Z, N, E components) of one earthquake _relative_ to each other.

The resulting wrong horizontal particle motion and wrong waveforms in the ray (LQT) coordinate system lead to

a wrong shear wave splitting measurement.

Here we provide a test with seismological data for your personal _SplitLab_ version and a suggested correction

of the _SplitLab_ function `getFileAndEQseconds.m` for the publicly available _SplitLab_ versions.

This modified _SplitLab_ function is also introduced by [_StackSplit_](https://github.com/michaelgrund/stacksplit)

([**_Grund, 2017_**](https://doi.org/10.1016/j.cageo.2017.04.015)) version [3.0](https://doi.org/10.5281/zenodo.5802051)

during the installation process.

## Citation

If you make use of this material, please cite the relating publication in which this issue is described in detail:

- [**_Fröhlich Y., Grund M. & Ritter J. R. R. (2022)_**](https://doi.org/10.4401/ag-8781).

  On the effects of wrongly aligned seismogram components for shear wave splitting analysis.

  *Annals of Geophysics*, volume 66, issue 2.

  https://doi.org/10.4401/ag-8781.

Furthermore you can cite the [Zenodo DOI](https://doi.org/10.5281/zenodo.5805029) given above.

## Content

- [`00_SAC_files`](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/tree/main/00_SAC_files)

  - Subfolders corresponding to some of the filename formats supported by _SplitLab_

  - Vertical (Z), North (N), East (E) components as SAC-files

  - Sampling interval: 0.05 s

- [`01_your_results`](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/tree/main/01_your_results)

  - Until now empty

  - Output folder for your own shear wave splitting measurement results

- [`02_SL_diagnosticplots`](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/tree/main/02_SL_diagnosticplots)

  - _SplitLab_ diagnostic plots for comparison (PDF and PNG formats)

  - Without (`*_wrong`) and with (`*_correct`) consideration of the milliseconds (msecs)

- [`03_SL_getFileAndEQseconds`](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/tree/main/03_SL_getFileAndEQseconds)

  - Modified _SplitLab_ function `getFileAndEQseconds.m`

  - Publicly available _SplitLab_ versions (`*_SLxyz`)

## Test

### How to do

**0) Choose one of the three provided examples (see subsection "Details on earthquakes and traces")**

  - Stuttgart (STU), 2001/06/29 (2001.180) 18:35 (UTC)

  - Stuttgart (STU), 2009/11/14 (2009.318) 19:44 (UTC)

  - Échery (ECH), 2018/08/28 (2018.240) 22:35 (UTC)

**1) Set up _SplitLab_ project**

Click for single steps



  - General

    - Seismic data directory

	  - Go to folder `00_SAC_files`

	  - Select subfolder with preferred filename format

    - Output directory

	  - Select folder `01_your_results`

  - Station

    - Stuttgart

      - Station code: STU

      - Network code: GE

      - Latitude in deg North: 48.771

      - Longitude in deg East: 9.194

    - Échery

      - Station code: ECH

      - Network code: G

      - Latitude in deg North: 48.216

      - Longitude in deg East: 7.159

  - Event window

    - Moment magnitude: 6.00 to 9.75

    - Epicentral distance in deg: 90 to 140

    - Hypocentral depth in km: 0 to 1000

    - Start and end date: corresponding to the date of the chosen example / earthquake

  - Phases

    - Earth model: IASP91

    - Phases: (at least) SKS, SKKS, PKS

  - Find files

    - File search string: corresponding to the chosen filename format

    - Offset: 0 s

    - Tolerance: 420 s



**2) Perform shear wave splitting measurement**

  - Bandpass filter: 0.020 Hz (lower corner), 0.20 Hz or 0.15 Hz (upper corner)

  - Coordinate system: LQT

  - Phase: SKS

**3) Compare your result / _SplitLab_ diagnostic plot with the provided diagnostic plots**

  - Folder `02_SL_diagnosticplots`: diagnostic plots for wrong and correct relative temporal alignment

  - Shape of the E-N particle motion: elliptic or linear?

  - SKS phase-related signal on the transverse (T) component: yes or no?

### Details on earthquakes and traces

Click for more information



**Stuttgart (STU), 2001/06/29 (2001.180)**

- Earthquake

  - Date: 2001/06/29 (2001.180)

  - Time: 18:35:51 (UTC)

  - Moment magnitude: 6.1

  - Source region: Southern Bolivia

  - Hypocentral depth: 274 km

  - Backazimuth: 246.5 deg

  - Epicentral distance: 95.29 deg

- Traces

  - msecs of start times: North = 0027, East = 0927, Vertical = 0627

  - Relative msec difference: |E-N| = |900|, i.e., |18| samples

**Stuttgart (STU), 2009/11/14 (2009.318)**

- Earthquake

  - Date: 2009/11/14 (2009.318)

  - Time: 19:44:29 (UTC)

  - Moment magnitude: 6.2

  - Source region: Jujuy province, Argentina

  - Hypocentral depth: 220 km

  - Backazimuth: 244.5 deg

  - Epicentral distance: 98.15 deg

- Traces

  - msecs of start times: North = 0145, East = 0895, Vertical = 0945

  - Relative msec difference: |E-N| = |750|, i.e., |15| samples

**Échery (ECH), 2018/08/28 (2018.240)**

- Earthquake

  - Date: 2018/08/28 (2018.240)

  - Time: 22:35:13 (UTC)

  - Moment magnitude: 6.5

  - Source region: Mariana Islands

  - Hypocentral depth: 60 km

  - Backazimuth: 40.1 deg

  - Epicentral depth: 106.00 deg

- Traces

  - msecs of start times: North = 0950, East = 0000, Vertical = 0950

  - Relative msec difference: |E-N| = |950|, i.e., |19| samples



## _SplitLab_ function `getFileAndEQseconds.m`

### _SplitLab_ versions

- [`03_SL_getFileAndEQseconds`](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/tree/main/03_SL_getFileAndEQseconds)

  - _SplitLab_ 1.0.5 (`*_SL105`) ([**_Wüstefeld et al., 2008_**](https://doi.org/10.1016/j.cageo.2007.08.002))

  - [_SplitLab_ 1.2.1](https://robporritt.wordpress.com/software/) (`*_SL121`) (**_Porritt, 2014_**)

  - [_SplitLab_ 1.3.0](https://github.com/nmcreasy/SplitLab1.3.0) (`*_SL130`) (**_Creasy, 2020_**; based on _SplitLab_ 1.2.1)

  - [_SplitLab_ 1.9.0](https://github.com/IPGP/splitlab) (`*_SL190`) (based on _SplitLab_ 1.0.5)

### How to do

- The filename part `xyz` or `x.y.z` indicates the _SplitLab_ version

- Go to the folder `~/SplitLabx.y.z/Tools/` on your computer

- Rename the existing function `getFileAndEQseconds.m`, e.g., `getFileAndEQseconds_original.m` in this folder

- Copy and past the modified function `getFileAndEQseconds_SLxyz.m` into this folder

- Remove the end of the filename `_SLxyz`

- **Assign earthquake catalogue and seismological data in your _SplitLab_ project**

## Releases

| Release | Zenodo DOI |

| --- | --- |

| dev [main branch](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment) |  |

| [v2.0](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/releases/tag/v2.0) | [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.13760807.svg)](https://doi.org/10.5281/zenodo.13760807) |

| [v1.0](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/releases/tag/v1.0) | [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.5805030.svg)](https://doi.org/10.5281/zenodo.5805030) |

For details on the single releases see the [changelog](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/blob/main/changelog.md).

## Contributing

For bug reports, suggestions, or recommendationsfeel free to

[open an issue](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/issues)

or [submit a pull request](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment/pulls)

directly here on [GitHub](https://github.com/yvonnefroehlich/SplitLab-TemporalAlignment).

## Related topics

In the table below, some other tools for measuring shear wave splitting (besides _SplitLab_)

are listed. Please note, that these tools were not checked regarding the issue

of an incorrect relative temporal alignment of the single component traces.

| Software | Language | Description | Author |

| --- | --- | --- | --- |

| SplitLab 1.0.5 | MATLAB | Original SplitLab version | Andreas Wüstefeld, Götz Bokelmann & Christophe Zaroli |

| [SplitLab 1.2.1](https://robporritt.wordpress.com/software/) | MATLAB | Update of SplitLab 1.0.5 | Rob Porritt |

| [SplitLab 1.3.0](https://github.com/nmcreasy/SplitLab1.3.0) | MATLAB | Update of SplitLab 1.2.1 | Neala Creasy |

| [SplitLab 1.9.0](https://github.com/IPGP/splitlab) | MATLAB | Most recent SplitLab version| IPGP |

| [StackSplit](https://github.com/michaelgrund/stacksplit) | MATLAB | Plugin for multi-event analyses in SplitLab | Michael Grund & Yvonne Fröhlich |

| [SplitRacer](https://www.miriam-reiss.com/splitracer) | MATLAB | Semi-automated workflow | Miriam C. Reiss |

| [SplitPy](https://github.com/paudetseis/SplitPy) | Python | Based on SplitLab | Pascal Audet & Andrew Schaeffer |

| [SWSPy](https://github.com/TomSHudson/swspy) | Python | Automated workflow | Tom Hudson, Andrew M. Walker & Joseph Asplet|

| [STADIUM-Py](https://github.com/earthinversion/STADIUM-Py) | Python | Fully automated workflow | Utpal Kumar & Cédric Legendre |

| [Pytheas](https://github.com/ispingos/pytheas-splitting) | Python | Local shear-wave splitting studies | Ioannis Spingos & George Kaviris|

| [Sheba](https://github.com/jwookey/sheba) | Fortran |  | James Wookey |

| [SeisSplit.jl](https://github.com/anowacki/SeisSplit.jl) | Julia |  | Andy Nowacki |

## References

- [**_Bowman, J. R. & Ando, M. (1987)_**](https://doi.org/10.1111/j.1365-246X.1987.tb01367.x).

  Shear-wave splitting in the upper-mantle wedge above the Tonga subduction zone.

  *Geophysical Journal International*, volume 88, issue 1, pages 25-41.

  https://doi.org/10.1111/j.1365-246X.1987.tb01367.x.

- **_Creasy, N. M. (2020)_**. SplitLab version 1.3.0.

  available at https://github.com/nmcreasy/SplitLab1.3.0.

- **_GEOFON Data Centre (1993)_**. GEOFON (GeoForschungsNetz).

  Deutsches GeoForschungsZentrum (GFZ), Seismic Network.

  https://doi.org/10.14470/TR560404.

- **_GEOSCOPE (1982)_**. French Global Network of broad band seismic stations.

  Institut de physique du globe de Paris (IPGP) & Ecole et Observatoire des Sciences de la Terre de Strasbourg (EOST).

  https://doi.org/10.18715/GEOSCOPE.G.

- [**_Grund, M. (2017)_**](https://doi.org/10.1016/j.cageo.2017.04.015).

  StackSplit - a plugin for multi-event shear wave splitting analyses in SplitLab.

  *Computers & Geosciences*, volume 105, pages 43-50.

  https://doi.org/10.1016/j.cageo.2017.04.015.

  versions [1.0](https://doi.org/10.5281/zenodo.464385), [2.0](https://doi.org/10.5281/zenodo.7118716), and [3.0](https://doi.org/10.5281/zenodo.5802051)

  available at https://github.com/michaelgrund/stacksplit.

- **_Porritt, R. W. (2014)_**. SplitLab version 1.2.1.

  available at https://robporritt.wordpress.com/software/.

- [**_Silver, P. G. & Chan, W. W. (1991)_**](https://doi.org/10.1029/91JB00899).

  Shear wave splitting and subcontinental mantle deformation.

  *Journal of Geophysical Research*, volume 96, issue B10, pages 16429-16454.

  https://doi.org/10.1029/91JB00899.

- [**_Walsh, E., Arnold, R. & Savage, M. K. (2013)_**](https://doi.org/10.1002/jgrb.50386).

  Silver and Chan revisited.

  *Journal of Geophysical Research: Solid Earth*, volume 118, issue 10, pages 5500-5515.

  https://doi.org/10.1002/jgrb.50386.

- [**_Wüstefeld, A., Bokelmann, G., Zaroli, C. & Barruol, G.  (2008)_**](https://doi.org/10.1016/j.cageo.2007.08.002).

  SplitLab: A shear-wave splitting environment in Matlab.

  *Computers & Geosciences*, volume 34, issue 5, pages 515-528.

  https://doi.org/10.1016/j.cageo.2007.08.002.

  version 1.0.5 **was** available at http://splitting.gm.univ-montp2.fr, version 1.9.0 is available at https://github.com/IPGP/splitlab.

## Funding

The presented research and YF received support from:

- Scholarship of the [Graduate Funding from the German States](https://www.khys.kit.edu/english/graduate_funding.php)