Earthquake Ground Motion Data Packet

Here we present a specification for a GeoJSON format for unassociated and event-associated ground motion metrics—that is, quantities derived from ground motion records (e.g., accelerograms, velocity recordings). We refer to this specification as a Ground Motion Packet (GMP). Common example metrics include peak ground acceleration (PGA), peak ground velocity (PGV), and spectral acceleration (SA). This format is designed so that it can also include metrics that are gaining popularity for many engineering use cases, such as significant duration, Arias intensity, and inelastic response spectra. This format should be able to be used by any application that uses ground motion metrics including, but not limited to, ShakeMap. The GMP format is not meant to describe station metadata or site installation. The purpose of the metadata included in the GMP format is to provide high-level information regarding the suitability of the data for common engineering/seismological applications.

Note that this ground motion packet is for ground motion metrics and not the waveforms themselves. Some metrics are associated with a single waveform, and others are associated with a group a waveforms. We apply ObsPy’s nomenclature of “trace” to refer to a single cotinuous time series, and “stream” to refer to a group of traces.

Attention

Although the use of the terms “trace” and “stream” is convenient for use in organizing waveform metrics, there is the potential for confusion since we are referring to the trace or streams from which the metrics are derived, and the waveforms themselves are not stored in the format presented here.