AT2 to TXT Converter

AT2 to TXT Conversion Explained

When you convert .AT2 to .TXT, you are transforming a specialized seismic acceleration data file into a standard plain text file. .AT2 files are already ASCII text, but they use a rigid, legacy structure—typically defined by the Pacific Earthquake Engineering Research Center (PEER). They contain a multi-line header with metadata (station name, earthquake, time step, number of points) followed by acceleration data printed in multiple columns per row to save space.

People convert .AT2 to .TXT to reshape this data. General-purpose software cannot easily read a file where data points wrap across multiple columns. Converting to .TXT usually involves stripping or commenting out the header and flattening the data into a single column of acceleration values, or a two-column format of time versus acceleration. You gain universal compatibility with math and spreadsheet software, but you lose the standardized PEER header format, which breaks compatibility with specialized seismic software that expects that exact structure.

Typical Tasks and Users

This conversion is highly specific to earthquake engineering and seismology. Common users and workflows include:

• Structural Engineers: Importing ground motion records into finite element software like SAP2000 or ETABS for time-history analysis.
• Geotechnical Researchers: Loading accelerograms into OpenSees to model soil liquefaction or site response.
• Data Scientists: Parsing thousands of seismic records into Python or MATLAB to train machine learning models on earthquake characteristics.
• Students: Opening seismic data in spreadsheet software like Microsoft Excel to plot response spectra or acceleration over time.

Software & Tool Support

Because both formats are text-based, you can open them with basic editors, but proper conversion requires data reshaping.

• Text Editors: Notepad++ or VS Code can open .AT2 files, but you must manually delete headers and use regular expressions to format the data.
• Seismic Software: Tools like SeismoSignal natively read .AT2 files and can export the processed data as .TXT or .CSV.
• Programming Languages: Python (using NumPy or Pandas) and MATLAB are the most common ways to automate this. Users write custom scripts to skip the first four header lines, read the dt (time step) value, and reshape the remaining matrix into a single vector.
• Convert.Guru: A web-based tool that automates the parsing and reshaping process without requiring custom code.

Pros and Cons of the Conversion

Pros:

• Universal Compatibility: A clean .TXT file with a single data column can be imported into almost any engineering, math, or spreadsheet software.
• Easier Parsing: Scripts do not need complex logic to handle multi-column wrapping or variable header lengths.
• Ready for Plotting: Two-column .TXT files (Time, Acceleration) can be instantly graphed.

Cons:

• Metadata Loss: Stripping the header removes critical context, such as the earthquake name, recording station, scaling factors, and units (e.g., g vs. cm/s²).
• Breaks Legacy Support: Software hardcoded to read the PEER NGA-West2 database format will reject a flattened .TXT file.
• File Size: Expanding a compact multi-column .AT2 file into a single-column .TXT file increases the line count and slightly increases the overall file size.

Conversion Difficulties & Why Convert.Guru

The main technical problem when you convert .AT2 to .TXT is the layout mapping. A standard PEER .AT2 file often prints five data points per line. Simply renaming the file extension from .AT2 to .TXT does not change this layout, meaning Excel or MATLAB will read it as five separate variables instead of a continuous time series.

To convert the file properly, the parser must read the header to identify the total number of points (NPTS) and the time step (dt). It must then extract the data block, flatten the multi-column array into a single continuous sequence, and optionally generate a corresponding time vector. Writing custom scripts to handle edge cases—such as trailing empty spaces on the final line of data—can be annoying and error-prone.

Convert.Guru handles this exact pipeline automatically. It detects the standard seismic header, safely extracts the metadata, and reshapes the acceleration array into a clean, single-column or two-column .TXT file. This provides an accurate, ready-to-import file without requiring you to write your own parsing algorithms.

AT2 vs. TXT: What is the better choice?

Which format should you choose?

You should keep your files as .AT2 if you are building a database of ground motions or using specialized seismic software that requires the PEER format. The .AT2 format safely preserves the earthquake metadata alongside the data points.

You should convert .AT2 to .TXT if you need to perform custom time-history analysis in structural software, plot the accelerogram in a spreadsheet, or process the data in a programming environment. If you do this, ensure you document the time step and units elsewhere, as removing the header deletes this information.

Conclusion

Converting .AT2 to .TXT makes sense when you need to extract raw acceleration data from a rigid, legacy seismic format and import it into modern, general-purpose engineering tools. The biggest limitation to watch for is the loss of the metadata header; you must remember your time step and unit scale once the header is gone. Convert.Guru is a reliable choice for this task because it correctly parses the specific multi-column layout of acceleration data files and reshapes them into clean, usable text columns, saving you the hassle of writing custom data-cleaning scripts.