A RZB-type Capacitive Borehole Inclinometer (RZB-type CBI) is designed to measure the inclination angle by the reaction of a capacitance with small displacement or small angle. It is characterized by high sensitivity (2×10−4 degree/sec.), good linearity (≤1%) and simple circuit structure. In addition, one pre-adjusting platform controlled by a micro motors is designed for this instrument to meet the requirement that an inclination sensor may change in a rather large range during downhole installation. In this paper, we introduce the operational principle and the constitution of RZB-type CBI and one application case in a borehole of 250-m depth. The measurement recordings show that this probe can detect the variation of Earth tide, the abnormal phenomenon before an earthquake and the seismic wave during an earthquake, which prove that this probe can meet the requirements to detect the inclination deformation of the upper crust.
The earthquake monitoring is an observation discipline and is always advanced by new observing techniques and methods. When force is acted on a part of the crust, stress and deformation will be produced, and then may result in an earthquake; therefore, there is surely a link between an earthquake and the crust deformation. The deformation observation has attracted much attention from the explorers of earthquake prediction and monitoring. The inclination deformation, vertical deformation and horizontal deformation are all necessary parts of stress and strain observation system (Ouyang Zuxi & Zhangjun & Chenzheng, et al., 2009, Qiu Zehua & Xie Furen & Su Kaizhi, et al., 2004). The high-precision inclinometer is mainly a gauge to observe the inclination deformation of upper crust, which can be used to detect small inclination variation, inclination earth tide and to capture the abnormal phenomenon shortly before earthquakes.