Andrew Pethick

About Andrew Pethick

Andrew is a geophysical software developer and has completed a PhD in electromagnetic computing and visualization.

GeoWiz - eMTEEBlackBox v1.01

GeoWiz - eMTEEBlackBox v1.0 : Open Source 1D MT Modelling software

So it's almost been a year since the Geophysics Hackathon run by Agile* Geoscience... I though I might expand on what impact the software our team has made since last October (2014). After making the 1D MT forward modelling software it undoubtedly had many bugs and was poorly constructed, but the idea and a bulk of the code was still pretty good considering the circumstances.

I will release the code after I fix up a few of the remaining bugs. I haven't asked them yet, but I also hope that MTnet can link to the software and help with integrating a few of the algorithms they think will be useful.
New Features
Many of the major bugs and have been fixed and the software expanded

At the conference we had several features:

Load ASCII MT data
Interactively forward model a 1D MT response
Display results

It has since gotten a bit of a polish:

Data export
PNG Export
Data Clearing
Plotting options
Unit conversion (m <-> ft) (mS/m<->S/m <-> Ohm.m) (Hz<->S)
Forward modelling algorithm selection (not just the awesome Java code written by Colton Kohnke) but the Python code written on Digital Earth Lab as well
Full JavaFX compatibility
Impedance Plotting
OSX/Win64 Compatibility

Soon to come:

A faster 1D MT Algorithm (written in c)
1D MT Inversion (Python algorithm complete not integrated)
Migration to Android and iOS via FXPorts
Impedance plotting (Yeah, why wasn't this a default option?)

How it has been used?

The best thing about this software is that it has become an invaluable learning tool. It is really easy to use, so easy in fact that the software is now integrated as part the Advanced Electromagnetic and Potential Field Methods in Geophysics 433 unit at Curtin University, soon to be integrated at 3rd year [...]

By |September 1st, 2015|app, Development, Hackathon|0 Comments

ASEG-PESA 2015 - Innovate or Perish?

The 2015 ASEG-PESA conference was an exciting one this year. From MT to muons, the scope and depth of the presentations have been inspiring.

The two plenary speeches by ASEG president Greg Street and PESA president Max Williamson offered no euphemisms or excuses when describing the current state of our industry. With such low commodity prices, we need to prepare now for when the good times return. Whilst both proposed alternative solutions, both were in clear agreement that the time for action has come.

Without government support recovery becomes difficult, but industry reliance dampens the pathway to innovation.  To justify our worth in today's global economy, we will need both imagination and hard work to develop solutions for collecting  greater quantities of higher quality data with economy. More importantly, we must be able to communicate information more effectively and intuitively across multiple disciplines. It was made clear that today's industry leaders are already beginning to retire. Our sector is aging. This is daunting news to hear as a young career geophysicist. We will soon need more young leaders ready to carry this torch to keep our industry moving forward. I am confident we be able to develop and extend today's technology after meeting so many talented young geoscientists.

I would like to thank the ASEG for awarding me the Shanti Rajagopalan Memorial Award. I feel privileged to receive this prize. The winning paper entitled "Bathymetry, electromagnetic streamlines and the marine controlled source electromagnetic method" was written as part of my PhD work in marine CSEM and published in Exploration Geophysics. The paper investigated the influence of sea floor topography on the electromagnetic fields generated during a marine controlled source electromagnetic survey. Streamlines are an underused yet intuitive approach [...]

By |February 17th, 2015|News|0 Comments Migration

I have finally migrated over to Digital Earth Lab. So I now have a single integrated website instead which is much easier for me to manage. The new MCSEM section can be found here and should soon redirect to Digital Earth Lab.

Marine CSEM modelling software download, new and improved introductory chapters into marine CSEM, and archived blogposts are now accessible.

By |February 12th, 2015|, News|0 Comments

Hackathon 2014 Denver Colorado

*Image accredited to Agile Geoscience

The premier geophysical programming event, AKA Geophysics Hackathon 2014 has concluded over an action packed weekend (Just prior to the 2014 SEG conference in Denver). First of all I would like to thank the team down at Agile Geoscience (Matt, Evan and Ben) for setting up such an awesome event, it's the first of its kind I have attended and if I can help it, not the last.

The weekend began bright an early at 8am on Saturday and after meeting with the rest of the "hackers" I realised I wasn't alone in the programming realm. There were OTHERS! It was amazing to see a diverse range of brilliant scientists in such a small place. I was privileged to be aligned with four other great individuals from NEOS and Colorado School of Mines, Josh Poirier, Colton Kohnke, Katerina Gonzales and Elijah Thomas. Our project was originally a "1D MT and Gravity Inversion Android App" however other ideas thrown around were,

The Web lazy LAS Viewer and Modeller
Online Geophysical Feasibility modeller
EM Cloud API

After a round of voting with a close 3-4-3-0 split, the MT App was our winner and even better our team "Geophys Wiz" was born. Like many young people we were very idealistic and ambitious. We had a plan.

Build a 1D MT viewer in android
Integrate 1D magnetotelluric forward modelling
Build upon the forward modelling and enable users to invert their data (soooo close)

Integrate gravity inversion to determine depth to basement

A simple 4 step plan. Yes. The problem. No experience with Android, two days to learn it and somehow produce a working 1D inversion mobile phone app behemoth. We were on track, after day one we essentially had an APK which could load in [...]

By |October 27th, 2014|Development, Hackathon|0 Comments

Online 1D Magnetotelluric (MT) Forward Modelling (Beta)

An 1D MT forward modelling web application. Following on from the 1D MT tutorial presented earlier, the concept is taken a little further and now the simulated magnetotelluric responses can now be easily computed and displayed all from your smartphone.

This is just a beta version so far, so expect a fully functioning version in the future with more computing and display options. You can see the code's progress on my Bitbucket repository.

UPDATE: Currently this webapp keeps breaking due to server limitations and I do not wish to constantly maintain it. I am looking to move this website to a better web server to take these webapps to the next level. I would like a company to sponsor the ongoing costs so I don't have to pay for cloud compute time out of my own pocket. Any forward looking companies willing to contribute? Contact me here..

By |July 14th, 2014|Forward Modelling, Magnetotelluric, News, Web App|0 Comments

Merging was a website I had maintained to provide my marine CSEM modelling software to the public. That project has now come to a close and I would like to focus my endeavors on topics not so specific to a single geophysical method. So instead of maintaining two website I am in the process of merging the content from to Digital Earth Lab. There will be some duplication in the meantime and there the site may be a little messy, so bare with me.

So if you would like to see what was about check out the following sections,

Introduction to Marine CSEM

or check out the previous entries,

By |June 21st, 2014|Uncategorized|0 Comments

Reading Large ASCII Datasets

Ever tried reading large geophysical ASCII data sets with a standard text editor only to get angry when it hangs, crashes or runs out of memory? Chances are you don't even want to edit the document but rather want to read the first one or two lines in the header. There are several solutions to solve this problem. First of all you can load the data into a software package which imports the data directly into a database (i.e., Oasis Montaj), but that requires you to load hundreds of megabytes or even  gigabytes of data, wasting minutes in the process. Secondly, if you are 'fortunate' enough to use a Unix based OS, you can use the "less" command, great for Linux users but pretty much worthless for Windows users.

If you want to try another solution out see below.

The source code is downloadable and is licensed under WTFPL. Distribute, copy, modify, sell, integrate, delete, make erroneous.... I really don't care what you do with it. The below source code is only a sample and does not represent the complete source code.
The premise
The header in a large ASCII text file can be read by storing one line at a time in memory. This avoids memory issues and consumes mere kilobytes of memory rather than trying to import gigabytes at a time.
The Solution
I have written some code using the JDK 8 developers release SDK containing the latest JavaFX libraries. This can be run under the Windows OS. The aptly named perpetual ASCII file viewer reads a file in blocks. Using Java this is accomplished by using the lines,

BufferedReader in;
public final TextArea t = new TextArea(); //Text area displaying the read text
private int preload, bufferSize; //preload 'preload' lines and load [...]

By |April 9th, 2014|News, Uncategorized|0 Comments

Open Source in Geoscience

Like everyone else who has dealt with Open Source software and libraries I have been seriously confused over what I could and couldn't legally do and the risks associated with developing open source. I have decided to write this page to assist those who are in the starting out in earth science software licensing.

So do You Really Want to be a 'Good' Guy?
I could go on forever about virtue and consequential ethics, but doesn't the bottom line trump these principles each time? I could also go on about the many articles spouting the benefits of open source for business but is it good path to go down?

The geoscientific sector is exceptionally unique. We are a small, highly specialized industry with many different sub-specialties and it is even more in our best interest to invest in this open business model. We have all seen the result of one or two companies dominating in highly specialized areas... outrageously expensive software licenses, limitations on software and equipment use, anti-competitive behavior and subversive tactics to steal the oppositions technology whilst internalizing potentially revolutionary ideas. So is there a good reason to continue along this trajectory? It promotes monopoly, inhibits start ups, squeezes dollars out of small to mid size companies and encourages a closed stagnant industry.

On the contrary most geophysical software packages have small user bases and profiting using open source paradigms is impossible without larger industry support. At the present I believe only open seismic software developers could survive. I developed an open source electromagnetic package during my PhD and I found the experience eye opening. Over its 3 year duration and 1500+ downloads, nobody submitted any fixes to the main source code or offered financial contributions (probably [...]

By |January 13th, 2014|News, Opinion|0 Comments

Tutorial - 1D Forward Modelling (Magnetotelluric)

I constantly ask myself where the hell are the geophysics tutorials? Coming from a programming background I find the extreme lack of geophysics tutorials concerning. If you want to solve the most trivial issues in computing the internet has it covered. When you look for trivial geophysics solutions they are nowhere to be found. As geoscientists, we live in a small industry and I expect less free online resources but come on, this is ridiculous.

As a start I include the following tutorial on 1D MT forward modelling. Hopefully it is easy to follow.

...and oh yeah.... the source code is downloadable and is licensed under WTFPL. If you don't know what WTFPL is, ill give you a hint "do what the _ you want to". So in other words, distribute, copy, modify, sell, integrate, delete, make erroneous.... I really don't care what you do with it.
The magnetotelluric (MT) method is an electromagnetic geophysical exploration technique. The technique utilizes natural sources of electromagnetic energy for very deep soundings of the earth for crustal, global, geothermal, mineral and hydrocarbon exploration.

We understand that magnetotelluric and telluric fields are large-scale low frequency electromagnetic fields generated by natural source electromagnetic source. The terms "magnetotelluric" and "telluric" are used to describe the fields and currents respectively. These MT sources generally occur outside of the earth including solar emission resulting from the diurnal variation of the earth's magnetic field (i.e., Arora's).

The point of this article is not to go in depth into MT interpretation or background but the formulation of the 1D solution. The derivation and background has been taken from several sources including Niwas et al. (2005) and Pedersen and Hermance (1986)

For a uniform geo-electrical earth the measured surface impedance is related [...]

By |December 17th, 2013|Forward Modelling, Magnetotelluric, News, Tutorial|0 Comments

Welcome to Digital Earth Lab

Welcome! Digital Earth Lab is an exciting new earth science blog covering all the interesting and controversial topics nobody seems to touch. Here at DEL we believe us earth scientists reside in a extremely litigious industry full of intellectual property lawyers and sociopaths jerks. So don't you wish we could adopt new paradigms to encourage technological advancement? As an attempt to open up the industry to new ideas we will start by amassing as many amazing open source earth science applications as we can under one roof. So please add us to your RSS feed and check back every one to two weeks for updates.


By |October 16th, 2013|News, Welcome|0 Comments