NARS IberArray (2011 – 2012)

NARS participated with 10 stations in the Spanish IberArray project for a period of one year. The IberArray seismic design includes the deployment of a dense array of new generation dataloggers equipped with broadband seismometers in an approximately 60×60 km grid. This network will cover Iberia and North Morocco in three successive footprints, each lasting for about 18 months. The equipment consists of Nanometrics Taurus dataloggers and Trillium 120s seismometers. Some of the nodes of the theoretical network are covered by permanent stations of the national broadband network (IGN) or other networks operating in the region (IAG-UGR, ROA). Data from those stations will also be integrated into the IberArray database.

Station list & data

Equipment

Seismometers

The seismometer used in the  IberArray project is the Streckeisen STS-2 broad band sensor, an electronic force-feedback sensor that provides an output signal proportional to ground velocity over a broad frequency range. Three identical, obliquely-oriented mechanical sensors are used and standard vertical and horizontal outputs are derived by summing the raw sensor signals within the sensors electronics. The housing is vacuum-tight and designed to minimize the distortion of the package by barometric pressure changes. The sensor is designed for quick and simple installation, wide temperature range operation, and secure transport, while resolving minimum earth noise levels over the frequency range.

NARS data logger

The Seismology group of Utrecht University together with the Instrumental group of the Physics department, developed the NARS seismic data logger. The data logger consists of mainly two components: (1) a data acquisition module, which does the AD conversion and timing. (2) an off-the-shelf embedded computer, for all further data processing. Data is stored on the data logger’s internal hard disk and (optionally) to an external USB stick. All communication with the outside world is done by network communication. The data acquisition module is similar as used with our previous NARS Baja project. For more detailed hardware information go to NARS data logger

Timing

For the NARS data logger timing we use the Trimble Acutime Gold GPS smart antenna. It generates a pulse-per-second (PPS) output synchronized to UTC within 15 nanoseconds, outputting a timing and position packet for each pulse.