Seismic sensors to prevent earthquake fatigue

Up to 9,500 tremors per day

Earthquakes are caused by shifts in the continental plates. At depths of three to 30 miles, they press against each other, rub, wedge and separate again. This leads to tensions that discharge and release energy. The Richter scale measures seismic energy released underground. Large-scale media coverage typically gets attracted by earthquakes with a magnitude of 6.0 or higher according to Richter. These occur around 20 times a year globally, with a potential of causing major destruction within an approximate 50-mile radius.

Less immediately critical, yet far more frequent are earthquakes measuring up to 3.0 on the Richter scale: They shake the globe up to 9,500 times – daily! We cannot notice most of these subtle vibrations. Regardless, buildings and infrastructure assets suffer tremendously from this constant infliction of stress over time. Specifically designed for the dynamics of these seismic vibrations, the ASC EQ series covers a wide range of vibration events, frequency ranges and amplitudes. With available measurement ranges of ±3 g and ±5 g, the signal-to-noise ratio (SNR) is around 113 dB at a bandwidth of up to 20 Hz, and around 108.5 dB at up to 100 Hz.

Continuous earthquake monitoring essential

However, the Richter scale doesn’t suffice for assessing the stress on buildings on the earth’s surface. To that end, earthquakes are classified according to their intensity. The twelve-point European Macroseismic Scale (EMS 1998) is widely used.

Intensity level VII corresponds to an average ground acceleration of around 1 m/s² (0.1 g, approximately 10% of gravitational acceleration), which already causes damage to buildings: Many solid constructions would suffer moderate damage (small cracks in walls, plaster falling off, parts of chimneys coming down). Buildings in poorer condition would suffer substantial cracks and the collapse of partition walls. According to current sources, around a quarter of the earth’s total land mass is at risk of suffering earthquakes of intensity VII and above.

Continuous monitoring of the structural integrity of existing buildings is, therefore, of great importance, even outside known earthquake zones. The construction of new buildings and infrastructure facilities is based on earthquake magnitudes and intensity levels measured in the region, in order to minimize risks to buildings and people.

For critical infrastructure, local monitoring is applied in addition to secure sensitive work and manufacturing processes, including semiconductor technology or hospital surgery. Here, the different propagation speeds of various seismic waves are exploited. Utilizing precise measurement technology of minimal latency, the fastest waves can be detected, processed and evaluated in real time to immediately initiate process interruptions or emergency shutdowns. The reliability of the engaged measurement technology is essential, as false alarms can also be serious and costly.

Flexible total solutions

“With the ASC EQ series, we offer highly flexible sensors of seismic measurement accuracy,” says Markus Nowack, Senior Application Engineer at ASC Sensors. “With this high-precision technology, we can provide straightforward, complete solutions to ensure the safety, longevity and stability of your building, business or facility. So that you can focus on what’s most important: delivering your services without disruption.”