Amplitude–Frequency Noise Models for Seismic Building Monitoring in a Weak-to-Moderate Seismic Region

Herein, we discuss amplitude–frequency noise models for high-quality accelerometric monitoring of a civil engineering building and the benefits of seismic building monitoring policies in weak-to-moderate seismic regions. Since 2004, the city hall building in Grenoble (French Alps) has been monitored continuously. First, accelerometric data from one continuous year are used to derive broadband noise models for the bottom and top of the building. The noise models are compared with (1) the noise sensitivity of the high-gain accelerometer installed in the building and low-cost sensor sensitivity models; (2) the typical earthquake response curves given by Clinton and Heaton (2002); and (3) the earthquakes recorded in the Northern Alps. Then, using earthquakes data, this study highlights threshold values for signal-to-noise ratio (≥3 or 9 dB) recordings of earthquake as a function of magnitude and distance for weak-to-moderate earthquakes. We present a preliminary cost-benefit analysis of instrumentation for such regions according to seismic hazard and instrumentation quality. For weak-to-moderate seismic regions like Grenoble area, the capability of high-dynamic accelerometers to record low-amplitude ground motions and building responses is confirmed and encouraged to enable high-quality observation of building response over a broad range of frequencies. Bearing in mind that full-scale building test data are of greater interest for improving our understanding of building response than even the most sophisticated models, the recording of weak-to-moderate earthquakes in building must be broadened using high dynamic instruments to obtain more comprehensive and advanced results.