Reliability of MEMS accelerometers for instrumental intensity mapping of earthquakes

Abstract

This work investigates suitability of low cost Micro-Electro Mechanical System (MEMS) sensors in strong motion related studies, particularly in dense arrays utilized in producing quick shaking intensity maps. Two types of MEMS sensors (MEMS-5 and MEMS-50) and a reference sensor are tested under excitations of sweeping waves and scaled earthquake recordings. Transfer functions and correlation coefficients are compared. As for earthquake recordings, comparisons are carried out in terms of basic strong motion parameters and elastic response of structures that influences the design majors. The performance of the MEMS-50 sensor is also investigated on free field conditions. Different sensing characteristics are compared by performing time frequency analyses of small earthquake ground motion recordings of the MEMS-50 based accelerometer and of a co-located reference accelerometer. Test results show that the MEMS-50 sensor is able to record the mid-frequency dominant strong motion parameters with high correlation, where the high frequency components of the ground motion are underestimated. Such a difference in strong motion parameters on the other hand, does not manifest itself on empirical instrumental intensity estimations. Strong motion parameters from the reference and MEMS sensors converge to the same seismic intensity level. Hence a strong motion network with MEMS-50 sensors could be a modest option to produce peak ground velocity-based damage impact of an urban area under large-magnitude earthquake threats in the immediate vicinity. MEMS-5, which is an upper quality ensemble, is recommended for wide range of application including peak ground acceleration-based and peak ground velocity-based rapid shake maps.