The Nederland Rapid Raw Strong Motion (RRSM) portal

The RRSM portal allows users to query earthquake information, peak ground motion parameters, response spectral amplitudes and to select and download earthquake waveforms within minutes after an earthquake with magnitude ≥ 2.0 occurring in the Groningen area of the Netherlands (see this note). Earthquake information, waveform data and automatically processed strong motion data are provided by the KNMI. Real-time RRSM processing started in September 2015, while past events have been processed separately in order to provide a complete database back to 2013.

The Nederland RRSM is based in the European RRSM, developed by ODC and ETH within the NERA project.

The RRSM is a KNMI system that delivers strong motion products close to real-time for earthquake scientists and earthquake engineers.

Key features of the RRSM:

  • It processes all available (and relevant) on-scale waveforms from the accelerometer stations of the KNMI Groningen's network that contribute data in real time.
  • It facilitates discovery and dissemination of peak ground motion parameters, earthquake information and related products, in near-realtime, and download of the raw, unprocessed event waveforms.
  • It uses fully automated processing software ("scwfparam") which is open source and integrated in SeisComP3.
  • It provides a simple and user-friendly web interface to query data.

The RRSM target community

The RRSM is significantly different from traditional dissemination systems of strong motion earthquake data in Europe, which have been characterised for decades by (large) delays in availability of reviewed, processed data. The RRSM concept reflects the current status in seismic monitoring where data users require rapid access to raw waveform data and metadata and do not rely on delayed processed waveforms.

With this background, the RRSM is particularly targeted towards rapid data access for:

  • Seismologists and strong-motion data analysts.
  • Earthquake and geotechnical engineers.
  • International earthquake response agencies.
  • The educated general public.

Disclaimer

The information provided by this portal has been automatically processed and it is intended only for research usage. The results are NOT reviewed by a seismologist. The KNMI declines any responsibility from any improper use of the information therein represented.

All waveform data within the RRSM are subject to this disclaimer.

Although the RRSM stands for a high-quality automatic processing of strong motion parameters, the reliability of this data strongly depends on the magnitude of the earthquake. The bigger the earthquake, the better the reliability of the parameters. In addition, the special nature of the seismicity in Groningen (induced and shallow earthquakes), makes the Nederland RRSM a product still in research and development.

Data gathering and processing

Raw waveform data and basic station information are available from the KNMI network.

The RRSM database is populated via a strong motion processing module "scwfparam" which is integrated in SeisComP3 (SC3).

The RRSM "scwfparam" processing is triggered after an earthquake is published by the KNMI.

Earthquake data is being processed if it meets the following criteria:

  • Magnitude (any scale) ≥ 2.0

Note: After the data gathering and filtering are done, only the stations that exceed certain STA/LTA threshold are further processed. This can result in situations where events which its magnitude is bigger or equal than 2.0 does not appear in this interface, because any station has been finally processed.

Waveform data are collected from accelerometer stations of the Groningen's network within 150km maximum epicentral distance. The length of the requested time windows is 60 seconds. The corner frequencies of the filter depend on the magnitude:

MagnitudeFilter frequencies
≥ 2 0.5 Hz – 80% Nyquist
≥ 3 0.3 Hz – 80% Nyquist
≥ 5 0.1 Hz – 80% Nyquist
≥ 7 0.05 Hz – 80% Nyquist
 

In addition, a post-deconvolution filter (0.05 Hz – 40Hz, order 4) is applied in the frequency domain to get rid of noise blown up by the process as well as possible distortions in the original signal.

Each earthquake is reprocessed after some time to ensure all available data to be included. Current scheduling is:

  • Immediately upon receiving alert
  • 10 minutes after origin time

The database is filled with data since 2013.

The webinterface

The user interface allows users to access both raw waveform data and peak ground-motion values as well as response spectral ordinates of engineering interest.

The RRSM Interface supports 3 different request types:

  • Select Events: search earthquakes by time, magnitude and location; get stream and peak-motions fulfilling the criteria.
  • Select Peak-Motions: search earthquakes by peak motion criteria; get stream and peak-motions fulfilling the criteria.
  • Combined Selection: search waveforms (earthquake-station combinations) by peak-motion criteria, station location, distance and magnitude; get stream and peak-motions fulfilling the criteria.

After submitting the search criteria, the earthquakes/waveforms are shown in the Results page. From there, the user can navigate through the Event detail page and/or the Station detail page.

Peak ground-motion values are shown on all page levels. The interface provides plots of peak amplitude versus distance for a selected earthquake, and response spectra for selected stations. In addition, the user can select a set of events/stations/streams to download raw wavefoms from KNMI Seismic & Acoustic Data Portal.

Notes

  • Only the most recently processed strong motion data is shown for each event.
  • The download capabilities of data tables (CSV, Excel, PDF, etc.) requires Adobe Flash Player.
  • Most of the features of this interface, as well as the Seismic & Acoustic Data Portal (for waveform download) requires JavaScript enabled.
  • Fully compatible with browsers Mozilla Firefox and Google Chrome.
  • Compatible with browser Internet Explorer ≥ 8, except for downloading raw waveforms via the Seismic & Acoustic Data Portal. Some other issues on IE8.

Notes on Ground Motion Prediction Equations (GMPEs)

  • GMPE v4 can only be shown at the location of the stations because it takes into account local site effects, which depend on the location.
  • GMPE v4 is computed combining 4 models (Lower, Central-lower, Central-upper and Upper) for the median predictions and 2 branches for the within-event variability (Phi).
  • GMPE v4 is computed using Rhypo, but plotted on Repi.
  • The standard deviation of GMPE v4 is composed by the variability at rock and the site-to-site variability, being combined in the most conservative way.

Acknowledgments

The adaptation of the European RRSM interface for Netherlands has been carried by the KNMI. The European RRSM interface was designed and implemented by Orfeus Data Center (ODC) and ETH Zurich, using funding from NERA. The waveform processing tool "scwfparam" within SeisComP3 was designed by ETH Zurich and implemented by Gempa GmBH. Funding for "scwfparam" development came from ETH Zurich, GNS New Zealand and Geoscience Australia. Details on "scwfparam" processing options can be found here.

SeisComP3 is an earthquake monitoring software developed by GFZ Potsdam and Gempa GmbH, largely used in Europe and worldwide.

The Seismic & Acoustic Data Portal is based in a software developed at GFZ Potsdam and adapted to The Netherlands by the KNMI.

The data user is kindly requested to provide proper reference to the data suppliers: data ownership acknowledgement

Data format and usage

The KNMI Seismic & Acoustic Data Portal allows download of time series data in Full SEED and Mini-SEED formats only.

Information about Full SEED and Mini-SEED can be found in IRIS (here and here), as well as the well-known libmseed library.

Very useful free software tools that can deal with Mini-SEED are Obspy and Geopsy. Other useful tools to view what it is inside a Mini-SEED file or to select specific data are miniSEED Inspector and dataselect, respectively.

Mini-SEED data can also be read in Matlab by means of a variety of scripts prepared by Matlab users and available on the Web. Another tool for Mini-SEED data visualisation and basic processing is PQLII, free software available from IRIS Passcal. Further, the reader is invited to evaluate the variety of free software resources provided by Passcal here.

As to data conversion, the reader is referred to the exhaustive list of tools provided by ORFEUS and IRIS, as well as the mentioned Obspy. This list includes software packages for conversion from Mini-SEED to ascii and SAC, the standard package for seismic data processing in many regions, in particular the US. For instance, rdseed can be used to convert SEED volumes into SAC compatible data.

Note on start/end time of the requested waveforms

Users might be interested in processing waveform data with start and end time that exactly match the start / end time of the requested time windows. Time synchronization typically does not occur automatically because - as SEED format is block-oriented - it is possible to have incomplete blocks in the waveforms retrieved from ArcLink.

Links

Other websites related to the Nederland RRSM Interface.

KNMI: http://www.knmi.nl/
KNMI Seismic & Acoustic Data Portal: http://rdsa.knmi.nl/dataportal
ORFEUS: http://www.orfeus-eu.org/
NERA project: http://www.nera-eu.org/
European Rapid Raw Strong Motion (RRSM) interface: http://www.orfeus-eu.org/rrsm
SeisComP3 scwfparam module: http://www.seiscomp3.org/doc/jakarta/current/apps/scwfparam.html


Disclaimer The peak-motion and spectral values provided through the RRSM Interface result from fast high-quality automatic processing of acceleration waveforms, without any human interaction. Please help us clearing severe mistakes if any, by sending your feedback through this contact form .
RRSM Interface © 2015 KNMI / ODC / ETH