GMT telescope seismic isolation system design and validation

The Giant Magellan Telescope (GMT) will be installed at Las Campanas summit in the Atacama Desert (Chile), one of the highest seismicity areas worldwide. To protect the telescope’s high-value optical systems and instrumentation, a seismic isolation system (SIS) has been devised. The SIS has a double function, to provide a high stiffness during normal observation for accurate tracking while allowing the telescope to move freely during an earthquake, filtering the seismic ground accelerations transmitted to the telescope, mirrors, and instruments. To achieve these two opposite functionalities, a combined SIS comprising single-friction pendulums, viscous dampers, fuses, a recentering system, and a health and safety monitoring system has been designed. The system has been validated through early prototypes and OpenSees finite element models considering multiple non-linearities as well as construction tolerances, uplift, and accidental torsion effects.