Electronic Supplement to
Call for Models—A Test Case for the Source Inversion Validation: The 2014 ML 5.5 Orkney, South Africa, Earthquake

by Pamela A. Moyer, Margaret S. Boettcher, William L. Ellsworth, Hiroshi Ogasawara, Artur Cichowicz, Denver Birch, and Gerhard van Aswegen

This electronic supplement contains tables of station locations (Tables S1 and S2) and seismograms in ASCII format.

Waveform Files

Three-component (north, east, and vertical) seismograms that were recorded by the Council for Geosciences (CGS) in South Africa are supplied for the 2014 ML 5.5 Orkney, South Africa, earthquake. These waveforms come from stations in the KOSH cluster of the CGS network, the cluster nearest the mainshock epicenter. Waveforms are given as acceleration, velocity, and displacement for each station. Each file contains a single waveform and begins with a five-line header identifying the station, component, record type (acceleration, velocity, or displacement), station location (latitude, longitude, and elevation relative to mean sea level), sample interval, and units. Each accelerogram header also indicates the arrival time (labeled as pick time) of the initiation of the ML 5.5 Orkney earthquake, which is the arrival time of the foreshock that precedes the main phase of moment release by ~1 s. The velocity and displacement waveforms start at the arrival time (pick time) given in the accelerogram records. The acceleration waveforms are each 30 s in duration, whereas the velocity and displacement waveforms are each 3.5 s in duration. The instrument transfer function for the accelerometers is given in the Instrument Information section. CGS station locations are given in Table S1.

The seismograms were processed as follows:

  1. Accelerograms were corrected for instrument gain.
  2. The P-wave arrival of the foreshock (or initiation phase) was identified.
  3. The mean value of the noise in the 1/2 s before the foreshock P-wave arrival was removed from the record.
  4. Accelerograms were integrated to velocity, beginning with the first sample of the foreshock P wave.
  5. The velocity record was integrated to displacement.

Instrument Information

Each seismic sensor in Table S1 consists of an EpiSensor from Kinemetrics. The Laplace transform of the EpiSensor accelerometer is


in which K1 is the normalization constant for the pole-zero representation, K2 is the instrument sensitivity in volts per acceleration (V/g), and the a.c. factor is a conversion factor from counts to volts (count/V). The values of the poles are






Table S1. Locations of stations with seismic data provided in orkney.seismograms.zip.

Table S2. Locations of stations for synthetic seismogram comparison.

Data File

Download: orkney.seismograms.zip [Zipped Plain Text files; ~3.7 MB]. This zip archive contains seismograms in ASCII format.

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