As part of an ongoing project to re-develop our strong motion products, we have some exciting updates to share with you.

So, what have we changed?

• Our Strong Motion Tool has been upgraded, based on end-user feedback (thank you to everyone who sent in feedback and suggestions).
• We have introduced new strong motion products.
• There are now different ways of accessing our strong motion products.
• We are transitioning from FTP-server to HTTPS.

What are the new access mechanisms for GeoNet’s strong motion products?

Strong Motion Tool

• An event-based GUI that allows plotting of data as well as data downloads.
• Provides a quick summary of seismic stations with data for an event.
• Has search options to sift through the database and check which events have strong motion products.

GeoNet data site

• The collection of processed strong motion data from 1966 to 2021, more popularly known as volume products, is accessible from this site.
• Moreover, bulk access of the archive of new strong motion products is also provided in this data site.

API

• Summary information for station peak ground motions is available herein, in JSON format.

How do the FTP-based products (also known as volume products) and data products from the Strong Motion Tool compare?

Similarities

• Both processed products are usually available for magnitude 4.0 and above earthquakes.
• Both datasets include filtered and unfiltered waveforms, response spectra and summary of stations with data.
• Both datasets are compiled on a per-event basis.
• Both datasets are processed using data streaming at 200hz.

Differences

• FTP-based products are in a proprietary format that requires an executable program to be converted to CSV. The new products are in GeoCSV format.
• Data files in FTP contained three tables stacked on top of each other corresponding to the three directions of motion (two horizontal and one vertical components). For the new products, each component of motion is presented in a per-column format.
• New products provide more event and station metadata.
• FTP-based products include Fourier spectra. In the new products, this data type is removed as per end user feedback.
• Processing of FTP-based products only uses triggered data from selected strong motion recorders. The new products make use of continuous waveforms.
• FTP-based products cover the earthquake events from 1966 to 2021. The new products are available for events from 1999 onwards.

What are the benefits of the Strong Motion Tool and the data site?

• The Strong Motion Tool provides a GUI that enables filtering of data products per station. It has better data access and support services.
• FTP site provides limited browsing capabilities. Also, most web browsers are deprecating the FTP-service for security reasons.

The changes in directory structure for FTP-service to HTTPS mount are summarized here:

When are the changes happening?

FTP-service will be decommissioned by the end of December 2021. We will stop the processing of the FTP-based products (aka volume products) as we switch off the FTP-service in December. We strongly encourage you to build your automated requests on the HTTPS mount.

If you have questions or would like assistance with these changes, please contact our support team via Email or catch us on GitHub.

Attributable to: Muriel Naguit – Seismology and Strong Motion Specialist

Media Contact: 021 574541 or media@gns.cri.nz