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Near-real-time matched-filtering for the development of dense earthquake catalogs during sequences of seismicity
  • Chamberlain Calum,
  • John Townend,
  • Matt Gerstenberger
Chamberlain Calum
Victoria University of Wellington

Corresponding Author:[email protected]

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John Townend
Victoria University Wellington
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Matt Gerstenberger
GNS Science-Institute of Geological and Nuclear Sciences Ltd
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Conventional earthquake detection methods suffer significant degradations in completeness during high-rate sequences such as aftershock sequences or volcanic swarms. Missed earthquakes during the early periods of aftershock sequences can affect aftershock forecasts and hazard estimates. Missed events during volcanic unrest sequences can impact rate estimations, leading to the sequence being mis-characterized. Much recent work has addressed how matched-filters can be used to overcome some aspects of catalog incompleteness during high-rate sequences, by detecting similar events using cross-correlation. Here we describe the application of open-source (GPL v3.0) software to the near-real-time implementation of matched-filter earthquake detection. Our software (RT-EQcorrscan) is written in Python, and leverages the extensive Obspy package, as well as EQcorrscan and Obsplus to provide matched-filter methods and database handling respectively. RT-EQcorrscan is designed to be modular, so that users can readily utilize only the components they require, or make use of pre-built command-line utilities controlled by simple that can handle thousands of templates over tens of channels of seismic data within the processing capacity (memory and CPU usage) of a standard desktop personal computer. Detections are made within a few seconds of data arriving, with latency due to data delivery and a requirement for full network move-out. At the same time, RT-EQcorrscan has an overarching “Reactor” module to listen to a web-service and respond to new events. If an event occurs that meets user-defined criteria, the Reactor will initiate a near-real-time matched-filter process encompassing the region surrounding the trigger event. Subsequent trigger events in different regions can also be handled with threaded operations. This system is backed-up by a constantly updating template database built on Obsplus, allowing groups of templates to be rapidly deployed. In this presentation we will discuss the key implementation details, as well as showcasing some examples of the system in operation.