GFZ Wireless Seismic Array (GFZ-WISE), a Wireless Mesh Network of Seismic Sensors: New Perspectives for Seismic Noise Array Investigations and Site Monitoring

Abstract

Over the last few years, the analysis of seismic noise recorded by two dimensional arrays has been confirmed to be capable of deriving the subsoil shear-wave velocity structure down to several hundred meters depth. In fact, using just a few minutes of seismic noise recordings and combining this with the well known horizontal-to-vertical method, it has also been shown that it is possible to investigate the average one dimensional velocity structure below an array of stations in urban areas with a sufficient resolution to depths that would be prohibitive with active source array surveys, while in addition reducing the number of boreholes required to be drilled for site-effect analysis. However, the high cost of standard seismological instrumentation limits the number of sensors generally available for two-dimensional array measurements (i.e., of the order of 10), limiting the resolution in the estimated shear-wave velocity profiles. Therefore, new themes in site-effect estimation research by two-dimensional arrays involve the development and application of low-cost instrumentation, which potentially allows the performance of dense-array measurements, and the development of dedicated signal-analysis procedures for rapid and robust estimation of shear-wave velocity profiles. In this work, we present novel low-cost wireless instrumentation for dense two-dimensional ambient seismic noise array measurements that allows the real–time analysis of the surface-wavefield and the rapid estimation of the local shear-wave velocity structure for site response studies. We first introduce the general philosophy of the new system, as well as the hardware and software that forms the novel instrument, which we have tested in laboratory and field studies.

Shear wave velocity versus quality factor: results from seismic noise recordings

“…large interstation distances for the outermost stations). The array measurements were performed on various stratigraphic units by different numbers of stations and combinations of instruments listed in Table 1, with digitizers from Guralp, Quanterra or the GFZ-WISE (see Picozzi et al 2010) connected to broad-band seismometers, short-period seismometers or geophones.…”

Combining Seismic Noise Techniques for Landslide Characterization

“…In particular, if the transmission of the entire recorded data is not required, each sensing unit can also perform a predefined set of calculations on the recorded data and only transmit the calculated parameters to the central acquisition center (Fleming et al 2009, Picozzi et al 2010). …”

Structural Health Monitoring Using Wireless Technologies: An Ambient Vibration Test on the Adolphe Bridge, Luxembourg City

“…Yet as shown by Picozzi et al [7,11], these WSUs are also highly attractive for monitoring critical infrastructure. Each WSU (Figure 1(d)) is composed of a low-cost three-component seismic sensor (thus far either a build-in accelerometer or an external 4.5 Hz geophone), a digitizer board with an effective resolution of 19 bit, onboard storage capability provided by a CompactFlash card and, as the designation "wireless sensing unit" indicates, wireless data transmission capabilities.…”

“…WSUs, we refer the reader to Fleming et al [12] and Picozzi et al [7,11]. For our measurements on the Adolphe Bridge, we used a total of 18 WSUs equipped with 4.5 Hz three-component geophones as sensors, and we recorded the ambient vibrations with a sampling rate of 100 samples/sec.…”