Performance Study of Nodal Sensors Based on Collocation Tests

Abstract With the increasing demand for nodal sensors in the industry and the seismological community, multiple commercial models have emerged in the market, making it essential to understand the potential limitations and variability among these models. We conducted a series of laboratory and field experiments to better assess their performance. First, shake-table tests were performed to determine the sensitivities of these nodal sensors. The results revealed that the tested sensors achieved accuracies within 30% of their nominal sensitivity values in the 0.1–10 Hz frequency range. Next, we conducted huddle tests in a bedrock chamber to estimate the self-noise of these sensors and compared their signal-to-noise ratios using recorded earthquake events. We found that self-noise exhibited an approximate 30 dB variation among different sensors and preamp gain options. In addition, we discovered that the tested sensor models displayed complex polarity definitions for their components compared to traditional seismometers. Finally, all sensor models were deployed at various field sites for approximately one month, followed by a comparative analysis assessing the retrieval of noise cross-correlation function from ambient noise. This analysis further elucidated their influence in field practice, demonstrating that the high-gain preamp option should be adopted for ambient noise imaging in far-inland areas for specific nodal sensors. Through these experiments, we aim to assist users in optimizing the application of nodal sensors in-field practice and provide valuable input to manufacturers for enhancing the overall performance of these sensors.