Long-baseline fluid tiltmeter for seismotectonic studies of Mexican subduction zone

Abstract

A long-baseline water tiltmeter (LBT) was constructed on the Pacific coast of Mexico to provide high precision tilt observations in a section of the subduction zone apparently undergoing interseismic-preseismic deformation phase. Continuous tilt complements GPS and vertical displacement (leveling) measurements by providing higher precision and continuous data. The plate interface is reasonably well located from local seismicity and gravity anomalies. Integrated geodetic and seismicity observations enabled us to monitor the strain near the upper and lower ends of a seismogenic zone on which a future M~7.0 earthquake is nucleating. Predicting the future rupture may be possible because the instrument is two orders of magnitude more sensitive than other monitoring devices in the region. Main principles, technical features and installation procedure of the water LBT and some preliminary observations and results are presented.