When the big one shakes the Rogue Valley, a new early-detection sensor on Roxy Ann should help give residents more advanced notice to drop, cover and hold on.

"Even if you get only 30 seconds while you're riding a bike near downtown Medford along the pathway, that would give you enough time to get away from the viaduct," said Leland O'Driscoll, University of Oregon seismic network manager.

The university, in collaboration with the Pacific Northwest Seismic Network at the University of Washington, plans to install a strong-motion seismic detector on Medford's closest peak this fall to collect information and provide real-time sensor data to the public.

The detection equipment is so sensitive it will pick up human movement atop the peak.

"If you're up there stomping around, you can read it on your cellphone," said Doug Gibson, research engineer with the seismic network.

Part of a system of detectors from California to British Columbia, the Roxy Ann equipment will help detect the strength and direction of a Cascadia subduction event that could wallop the Pacific Northwest with a magnitude 9.0 quake, potentially bringing down the Interstate 5 viaduct and leaving the Rogue Valley isolated for months.

A Cascadia subduction quake last occurred in 1700, and geologists have predicted we're about due for another one. Subduction refers to two tectonic plates grinding against each other in the Pacific that finally build up enough pressure that they release a tremendous amount of energy that we feel as an earthquake.

A portion of a grant from the Oregon Department of Geology and Mineral Industries will fund the $11,000 project, which is just the start of an advanced early-warning system that may someday take a more proactive approach to earthquake preparedness. The city of Medford is being asked to support the project and will provide a data link from Roxy Ann that will send information to Seattle.

In the future, O'Driscoll said, there will be a greater effort to minimize the damage from quakes and to provide more alerts to the public.

"Part of the end game is that we want the natural gas valves to shut off automatically before an earthquake hits," O'Driscoll said.

While an automatic gas shut-off valve is an idea for the future, O'Driscoll said a more near-term automatic alert system, similar to Amber Alerts, would notify residents by cellphone that an earthquake is about to hit. He said that would take some effort on the part of phone makers and phone companies, though the technology is available in other countries.

O'Driscoll said a software system that is already being tested on computers would give real-time alerts of a seismic event. Local media outlets could be part of the beta testing of the new system and could relay the information to local residents.

He said the system is currently buggy and sometimes gives false alerts, which should be ironed out as the software is refined.

The Oregon Department of Transportation is also going to look at installing seismic detectors on bridges that could determine how much shaking has occurred to alert motorists of potential dangers ahead, he said.

O'Driscoll said the new seismic detector would be installed on the very top of Roxy Ann Peak. There is a tall communications tower on the peak, along with a shorter tower and a small building next to it.

The detector would be installed in the small building and would have a battery pack that would keep it running for up to four days if the power was disrupted.

O'Driscoll said there are two early-warning detectors in operation in the valley, one at Southern Oregon University and the other near the Table Rocks, run by the University of California, Berkeley. SOU upgraded its detector last winter.

Two other detectors, at Applegate Reservoir and Lost Creek Dam, don't provide real-time information, O'Driscoll said.

More detectors help increase accuracy and help push out the alerts more quickly, similar to two eyes providing better depth perception than one eye.

The amount of detection equipment required to improve alerts is determined by the population of an area and proximity to faults.

"Medford is not as populated but is at greater risk," O'Driscoll said.

If a quake happened right off the coast, Medford would have about a 30-second warning. If the quake struck British Columbia or Washington, it would have a three- to four-minute warning, maybe five, O'Driscoll said.

He said a five-minute warning should give most people time to move away from unreinforced masonry buildings or from buildings with lots of glass.

The network, located at the University of Washington, has a website with information about quakes and where the detectors are located: https://pnsn.org/.

Gibson said seismic activity recorded at Roxy Ann will be available almost immediately on the website.

The last sizable quake in Southern Oregon was in 1993 in Klamath Falls, measuring under 6.0, O'Driscoll said.

Evelyn Kent, a 17-year-old Crater High graduate from Medford, hiked to the top of Roxy Ann Tuesday and is excited to learn about the earthquake detector.

"I do a lot of research and like learning about this," she said.

Kent said she thinks the valley has a strong community that will pull together even if the area becomes isolated from the world for a period of time, though she thinks the area relies on a lot of stuff being shipped here.

Her friend, William Hutson, an 18-year-old Crater High graduate from Central Point, said, "We have a lot of good people here and a lot of goodwill."

— Reach reporter Damian Mann at 541-776-4476 or dmann@mailtribune.com. Follow him on www.twitter.com/reporterdm.