Hawaii island police are investigating $50,000 in damage to a fiber-optic cable line on Mauna Kea.

A criminal property damage case was initiated after police say an employee with Mauna Kea Observatories reported the damage Thursday after trying to determine the cause of a June 24 malfunction. The buried fiber-optic line links observatories on Mauna Kea to the University of Hawaii network.

Technicians said a cable in a conduit about halfway between Hale Pohaku and the summit had been “tampered with and then pushed back into the conduit to avoid detection.” The damage, estimated at $50,000, occurred in a utility vault next to a service road about 700 feet from Mauna Kea Access Road.

The lines are also used to provide GPS information to ships and airplanes and are part of an earthquake detection system.

Built-in redundancies in the network prevented the damage from interrupting service to the observatories, according to UH spokesman Dan Meisenzahl.

On June 24 a caravan of construction vehicles on the way to Mauna Kea’s 13,000-foot summit was turned around after protesters opposed to the building of the Thirty Meter Telescope covered the roadway with boulders at the 10,000-foot level. State and county officers arrested 11 people who refused to leave the road leading to the summit.

Construction has not resumed.

Anyone with information about the damage to the fiber-optic cable line is asked to call the Hawaii Police Department’s nonemergency line at 935-3311 or contact Officer Jerome Duarte at 961-2211.