# MSNoise 1.6¶

Release date: 3 September 2019

Release type: major

Release notes:

## Introduction¶

More than 2 years after the last major release (MSNoise 1.5) I’m proud to announce the new MSNoise 1.6. It is a major release, with a massive amount of work since the last one: in GitHub numbers , it’s over 190 commits and over 4000 lines of code and documentation changed or added!

End of summer is also a very special period for MSNoise, as it has been 9 years since Corentin contacted Florent and that I immediately started working on this package. 2010-2019. Nine years. Wow. MSNoise has now a few thousand lines of code and more than 100 pages of documentation, it is widely used and scientists around the globe use it and even make super cool publications out of their results! So proud!

MSNoise 1.6 introduces a series of new features :

• The workflow has been rewritten to create “job types” per step, making it easier for users to reset a jobs before a specific step.

• This and other smaller adaptations to the code allows to run MSNoise more efficiently, e.g. on a HPC (see hpc).

• The components to compute can be defined for “single-station” and “cross-station” independently.

• The compute_cc step has been completely rewritten to be much, much faster.

• A new db top level command, which among others include dump and import commands for handling the tables from the database.

• A new Interaction Examples & Gallery section of the documentation in order to demonstrate how users can interact with the MSNoise API, e.g. for creating custom plots.

As always, this version has benefited from outputs/ideas/pull requests/questions from several users/friends.

Thanks to all for using MSNoise, and please, let us know why/how you use it (and please cite it!)!

To date, we found/are aware of 70 publications using MSNoise! That’s the best validation of our project ever and it has doubled since last release!!

Thomas

PS: if you use MSNoise for your research and prepare publications, please consider citing it:

Lecocq, T., C. Caudron, et F. Brenguier (2014), MSNoise, a Python Package for Monitoring Seismic Velocity Changes Using Ambient Seismic Noise, Seismological Research Letters, 85(3), 715‑726, doi:10.1785/0220130073.

## Requirements¶

This version will be the last to be tested on Python 2.7. The EOL (end of life) of 2.7 is 2020, which means it is high time for users to migrate. For users having a complete set of tools in Python 2.7 and not keen to move to 3.x soon, the incredible easiness of creating a Python 3.x environment in conda, for example, will allow them to run MSNoise in the future.

There were no changes in the requirements. Note that MSNoise is always tested against the latest release versions of the main packages, so older installations that are not maintained/updated regularly (years) could encounter issues. Please make sure you have the latest version of Numpy and Scipy (and MKL), as performance gets better and better (especially since Anaconda Inc. released its fast MKL implementations for all users, in the conda-forge channel).

## Configuration Parameters¶

• ADDED: hpc for flagging if MSNoise is running High Performance. If True, the jobs processed at each step are marked Done when finished, but the next jobtype according to the workflow is not created. This removes a lot of select/update/insert actions on the database and makes the whole much faster (See hpc).

• ADDED: archive_format will tell the obspy.core.stream.read ObsPy function the format of the files to read in the archive during the scan_archive stage. If left empty, obspy.core.stream.read will automatically detect the format of the file, which results in a slightly slower reading.

• ADDED: whitening_type to allow for the standard brutal whitening (all-to- 1.0) or whitening by dividing by the PSD of the signal.

• ADDED: components_to_compute_single_station to separate the components computed for single stations and cross-stations. For example, the ZZ can be computed for STA1 vs STA2 and, at the same time, EZ,EN,EZ for STA1 and for STA2.

• ADDED: stretching_max and stretching_nsteps for computing the stretched reference function between [1-stretching_max:1+stretching_max] with stretching_nsteps number of steps.

• CHANGED: cronday should now be a positive float number (negative numbers are still accepted for backward compatibility) or a string designating any optional number of weeks, days and/or hours in the format ‘Xw Xd Xw’ in this order, where a week represents 7 days (some valid examples would be: ‘1w 3d 6h’, ‘2w 1d’, ‘1d 12h’, or ‘6h’). Its meaning is unchanged: if the --init option is not used, scan_archive will only scan files modified during the time in the past designated by crondays .

## Workflow changes¶

The workflow has been rewritten to create “job types” per step, making it easier for users to reset a jobs before a specific step.

New job types are:

• A STACK job is created when a CC job is successful

• A MWCS job is created when a STACK job is successful

• A DTT job is created when a MWCS job is successful

About the STACK jobs, it is important to call the “ref stack” before the “mov stack”, as the “ref stack” will run on the STACK jobs, check if any date matches the date range of the ref_begin - ref_end, do the stacks if needed, then will not reset the STACK jobs to Todo so that “mov stacks” can be done.

## Pre-processing and Cross-Correlation¶

### Pre-processing¶

• Only small changes were done for this step, mainly checks of matching sampling rates, empty streams. DB-related optimisations make this step faster too.

### Cross-Correlation¶

• The compute_cc step has been completely rewritten to make use of 2D arrays holding the data, processing them “in place” for the different steps (FFT, whitening, etc). This results in much more efficient computation. The process slides on time windows and computes the correlations using indexes in a 2D array, therefore avoiding an exponential number of identical operations on data windows.

• This new code is the default compute_cc, and it doesn’t allow computing rotated components. For users needing R or T components, there are two options: either use the old code, now named compute_cc_rot, or compute the full (6 components actually are enough) tensor using the new code, and rotate the components afterwards. From initial tests, this latter solution is a lot faster than the first, thanks to the new processing in 2D.

• It is now possible to do the Cross-Correlation (classic “CC”), the Auto- Correlation (“AC”) or the Cross-Components within the same station (“SC”). To achieve this, we removed the ZZ, ZT, etc parameters from the configuration and replaced it with components_to_compute which takes a list: e.g. ZZ,ZE,ZN,EZ,EE,EN,NZ,NE,NN for the full non-rotated tensor between stations. Adding components to the new components_to_compute_single_station will allow computing the cross-components (SC) or auto-correlation (AC) of each station.

• The cross-correlation is done on sliding windows on the available data. For each window, if one trace contains a gap, it is eliminated from the computation. This corrects previous errors linked with gaps synchronised in time that lead to perfect sinc autocorrelation functions. The windows should have a duration of at least “2 times the maxlag+1” to be computable.

• The whitening procedure can be skipped by setting the whitening configuration to None. The two other whitening modes are “[A]ll except for auto-correlation” or “Only if [C]omponents are different”. This allows skipping the whitening when, for example, computing ZZ components for very close by stations (much closer than the wavelength sampled), leading to spatial autocorrelation issues. “A” and “N” are supported by the new compute_cc, while “C” is only supported by the old version, now named compute_cc_rot.

## Command Line changes¶

### Top level DB command¶

I’ve added a new command group called db that gathers all db-related actions:

• msnoise db init is a replacement for the msnoise install

• msnoise db upgrade is a replacement for the msnoise upgrade_db

• msnoise db clean_duplicates deletes duplicate jobs (might happen). Unique sets of day, pair and jobtypes are considered.

• msnoise db execute allows executing SQL queries on the database (Expert Mode). If the query includes a SELECT command, the result is returned as a table.

• msnoise db dump allows dumping all tables from the database to CSV files

• msnoise db import allows importing individual tables and replace them in the database.

The config command group has been reworked and the get sub-command has been added to retrieve the values of a list of configuration parameters:

• msnoise config get <param> will display the value of the configuration parameter <param>.

• msnoise config set <param>=<value> will set the value of the configuration parameter <param> to <value>.

• msnoise config gui will run the deprecated configuration graphical interface (that was previously available through msnoise config but supersed by the web interface using msnoise admin).

• msnoise config sync synchronises station metadata from inventory/dataless (was previously available as msnoise config --sync).

### Other changes¶

• msnoise info also prints information stored in the db.ini file (for security reason, the password is masked in the output but be aware that it is still stored in clear text in the file.).

• msnoise info -j reports all jobs types, including those of plugins.

• Added the possibility to walk in sub-folders recursively by using scan_archive --path -r

Note, all commands are documented: Help on the msnoise commands.

## API Changes¶

• New get_params API method to return a Params class containing all configuration bits, avoiding unnecessary calls to the DB later. This method will automatically populate from the defaults and return elements having the right type.

• Many (many) small optimizations to the core functions to make them faster, mostly when interacting with the DB, thanks to get_params.

• update_config can now modify parameters for installed plugins.

• New massive_update_job to update a list of Jobs to a given flag.

• build_ref_datelist and build_movstack_datelist return the smallest date from the data_availability table if the ref_begin or startdate have not been modified from their default value of 1970-01-01.

• Removed linear_regression as this is now included in ObsPy.

• Modified get_dtt_next_job returns jobs in random order.

• Added missing documentation for several methods.

See MSNoise API.

## Performance and Code improvements¶

### High Performance - Reducing DB access¶

Most of the API calls have been cleaned from calling the database, for example the def stack() called a SELECT on the database for each call, which is useless as configuration parameters are not supposed to change during the execution of the code. This modification allows running MSNoise on an HPC infrastructure with a remote central MySQL database.

The new configuration parameter hpc is used for flagging if MSNoise is running High Performance. If True, the jobs processed at each step are marked Done when finished, but the next jobtype according to the workflow is not created. This removes a lot of select/update/insert actions on the database and makes the whole much faster (one INSERT instead of tons of SELECT/UPDATE/INSERT).

Commands and actions with hpc = N :

• msnoise new_jobs: creates the CC jobs

• msnoise compute_cc: processes the CC jobs and creates the STACK jobs

• msnoise stack -m: processes the STACK jobs and creates the MWCS jobs

Commands and actions with hpc = Y :

• msnoise new_jobs: creates the CC jobs

• msnoise compute_cc: processes the CC jobs

• msnoise new_jobs --hpc CC:STACK: creates the STACK jobs based on the CC jobs marked “D”one

• msnoise stack -m: processes the STACK jobs

• msnoise new_jobs --hpc STACK:MWCS: creates the MWCS jobs based on the STACK jobs marked “D”one

### Rework of scan_archive¶

The code behind the scan_archive command has been deeply reworked to ease maintenance and debugging, and the reading of the files and directories has been improved thanks to the scandir function included in Python 3.5 and backported in the scandir module. The multiprocessing strategy (used if the -t/--threads option is provided) has also been reworked to limit the expensive step of process creation: the list of directories to scan is now split at startup and each child process concurrently treats an equal part of it.

### Prefix of database tables¶

The new msnoise db init project initialisation command now prompts you to choose an optional prefix for the name of the tables that will be created in the chosen database. If you enter the prefix myprefix, the tables will be named using the prefix myprefix_. This allows to share the same database with several MSNoise projects.

### Comparison with MSNoise 1.2 as published in the SRL article:¶

In the 2014 SRL article, we computed the dv/v for the UnderVolc project on a 4vCPU virtual machine running on a powerful ESX system. For this test, I analyzed the same data set on a 4 year-old 16 CPU blade. The timings mentioned below are then multiplied by 4 to account for the CPU number difference.

Summing the total time needed, we reach 37 hours for the SRL version, and 12 hours for MSNoise 1.6. The speedup is not fully linear, as the current code supports running on over 500 CPUs (as long as your MySQL server can handle it) but no MySQL server could have handled the so many connections/requests from the old version. The compute_cc2 computation time scales roughly linearly with the amount of components, contrary to the old compute_cc which was exponential).

STEP

v1.6 (16 CPU)

v1.6 (4 CPU)

SRL (4 vCPU)

SPEEDUP

scan_archive

385 seconds

1540 seconds

1800 seconds

1.2x

new_jobs

27 seconds

27 seconds

1800 seconds

66.0x

compute_cc2

4817 seconds

19268 seconds

75600 seconds

3.9x

stack -r

58 seconds

232 seconds

1980 seconds

8.5x

stack -m

1124 seconds

4496 seconds

21600 seconds

4.8x

compute_mwcs

4209 seconds

16836 seconds

28800 seconds

1.7x

compute_dtt

264 seconds

1056 seconds

3600 seconds

3.4x

Total

10884 seconds

43455 seconds

135180 seconds

3.1x

Total (hours)

3 hours

12 hours

37 hours

3.1x

Next steps of improving this workflow will be:

• Reduce I/O: by storing the mov_stack elements in two-dimensional HDF5 dataframes

• Reduce CPU: by computing the mov_stack in a 2D Pandas DataFrame directly

• Reduce CPU: by pre-computing MWCS windows and pair-wise computing the delays (reduces drastically the number of FFT calls)

If anyone feels like focusing on those aspects and providing Pull Requests, welcome!

## Other changes¶

• Feature: The pagination size (100, 200, etc. row) is now allowed on the Station, Job and DataAvailability views.

• Feature: The Config list view can be sorted by name.

• Feature: The home page has changed to show all job types and exposes buttons to execute actions equivalent to msnoise reset in the console.

• Some plots now accept extra arguments, like setting the x-axis limits for the ccftime plots to zoom automatically on a portion of the time-lag axis. The command is msnoise plot ccftime --xlim=-10,10. This is particularly useful when producing the images in routine, like in an Observatory.

See Plotting.

### Documentation¶

• The layout/theme of the Documentation has been changed to be more readable.

• New elements for configuring MySQL and MariaDB, thanks to Lukas Preiswerk.

• The description of the new steps and the HPC mode.

• Most of the plots for the documentation have been remade using the Undervolc dataset provided during MSNoise Workshops. The new Interaction Examples & Gallery section of the Documentation provides new ways for users to generate their own plots easily.

## Upgrading an existing project to MSNoise 1.6¶

Some users will want to keep their current project without recomputing everything. This requires adding a few configuration parameters to the database

Running the following command will take care of the upgrade from 1.5 to 1.6:

msnoise db upgrade


## A final note about development pace and choices¶

• MSNoise team is

• 1 developper (Thomas)

• 1 dedicated debugger (Corentin)

• less than 10 really active users, providing feedback and/or lines of codes (Arnaud, Esteban, Raphaël, Aurélien, Carmelo, Clare, Rob …)

• All software engineering ideas are coming from too infrequent beerstormings between Thomas & others

• The web-interface and the plugin support were developed during Thomas’ holidays

If you need help, please ask your questions on the mailing list. Don’t be afraid to ask. If you have ideas, please share them. If you develop codes to supplement MSNoise, please share them, even if very small, even if you don’t master gitHub. If you have complaints, post them too, but remember that the package you are using has been coded by 1 person, and that it’s not his full time job. So MSNoise is provided “as-is”, carefully written and tested, but there will be bugs, issues, incompatibility with certain python installations, OS or module versions. If you want or need developments made, contact Thomas via email directly. If these developments are within the focus of the developers’ research, then a collaboration, i.e. resulting in a co-authored peer reviewed publication, can be an option. Otherwise, you can contract us for paid-developments.