On the Identification and Documentation of Timing Errors: An Example at the KBS Station, Spitsbergen

Abstract

The availability of high-quality digital seismic data has never been better than it is today. Through consortia such as the Incorporated Research Institutions for Seismology (IRIS) and Observatories and Research Facilities for European Seismology (ORFEUS), waveform data from stations of many worldwide networks are available via the Internet to the international community of seismologists. When a user examines a segment of data, it is assumed that the time displayed is the exact time in Coordinated Universal Time (UTC) at which the motion was recorded. In general, when retrieving data segments from a waveform repository, there is no independent confirmation of the validity of the time stamp. In this paper, I discuss a case where a user discovered an erroneous time stamp on data from a single-site station. A fortuitous source of repeating seismic signals, together with data from another nearby station, facilitated measurement of the timing anomaly during the period in question. Erroneous timing on seismograms might be more widespread than assumed; the identification and documentation of such cases requires more attention. The IRIS/GEOFON/AWI seismic station at King's Bay Station (KBS) is situated near Ny Alesund, King's Bay, on the Arctic island of Spitsbergen (figure 1). The location is important in the context of nuclear-explosion monitoring due to the relative proximity of the Russian island of Novaya Zemlya, the site of numerous Soviet-era nuclear tests, the last known event being on 24 October 1990. Also on Spitsbergen, a highly sensitive small-aperture seismic array, SPITS, became operational in 1994 and is now a designated Auxiliary Seismic Array (AS72) of the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO). However, the KBS station is still of great importance given both the high quality of the continuous seismic data and the availability of the historical data recorded at that site. …