This is one in a weeklong series of stories on KPCC leading up to Friday's 20th anniversary of the devastating 1994 Northridge Earthquake. The series will explore the quake's history, its effects and its legacy. You can view more stories on our Northridge Anniversary page. Let us know what you think on our Facebook page, on Twitter ("@" mention @KPCC) and in the comments below.

The 1994 Northridge earthquake came as a total surprise: That magnitude 6.7 temblor shook on a previously unidentified fault and caused at least 57 deaths and more than 9,000 injuries.

Twenty years later, how close are we to predicting the next earthquake?

In the future, Californians may get a warning — as much as a minute or more — before certain kinds of earthquakes start to shake their homes and offices, but only if the state can find a way to expand the bare-bones early warning system currently being developed.

RELATED: Timeline: Northridge Earthquake devastates L.A. in 1994

Caltech, UC Berkeley and the U.S. Geological Survey are testing an earthquake early warning system that relies on sensors placed around the state.

These sensors can detect the tiniest of vibrations, says Caltech instrument specialist Russell Oliver.

For instance, he explained, if you put the sensor on one end of a football field and raised the opposite end by just the width of a human hair, the sensor would detect that. They are also able to detect forces as large and as subtle as the gravitational pull of the moon.

That level of sensitivity is important to help scientists pinpoint exactly where a quake originates and how fast and far it is spreading.

These machines don't come cheap, though: They can cost up to $17,000 each.

Right now, the system has about 400 sensors, some on mountaintops, others in forests, some in the desert or even in office buildings.

Faster than an earthquake

The goal of this system is to warn people seconds after an earthquake has started so they can get to safety before the shaking reaches them.

For that to work, these super sensors need to be able to send alerts faster than the seismic waves travel through the earth.

Ken Hudnut, a geophysicist with USGS, says the system mostly does that using a cell modem network, similar to what smartphones use.

"We are relying on it way too much actually," Hudnut remarked.

He worries that a major quake would knock out the cell network making the warning system ineffective. Ideally, he says, the system would have multiple ways of sending data, from radio towers to fiber-optic cables.

"We just can't afford it," Hudnut explained.

RELATED: Northridge Earthquake 20 years later: Then and now photo gallery

The final step in the warning system is the warning itself.

Caltech's Tom Heaton has a prototype of the quake alert system installed on his office computer. If a quake struck, an alarm would sound telling him how much time he had until the shaking reached him.

Depending on how far away the quake is, Heaton could get a minute's warning, but if the epicenter is close by, he may get no warning or at most a few seconds to drop and cover.

Of course, the goal is to do more than just warn Caltech professors. Heaton hopes one day all Californians will get a quake alert before the ground beneath them starts to move.

"Or, in the more common situation, it won't even tell them; it would tell their elevator: 'Go to the closest floor, open the door and tell them to get out of it.' Or it may tell their train to slow down."

Japan's experience

That's what happened in Japan during the quake and tsunami combo of 2011.

Heaton spent a few months in Japan studying its early warning system, which dates back to the 1960s. He says the country, which is smaller than California, is covered in thousands of sensors and has spent up to a billion dollars on its network.

In contrast, California's pilot warning system of only 400 sensors runs on about $15 million dollars a year, a large part of that goes to maintaining the system and paying staff to work with it.

To upgrade this network to something more robust, Heaton estimates the budget would need to at least double.

"It's not expensive, it's just expensive compared to what we've been spending which is a very small amount."

Finding funding

State Senator Alex Padilla helped pass a bill last year that asks the state to find funds to build out the warning system.

"The project is a small investment for the potential benefit," said Padilla.

The bill requires the California Office of Emergency Services to look for a way to expand the system without using general funds. Padilla hopes this process can raise $80 million dollars through a combination of state money, federal grants and contributions from private companies.

However, if no funding mechanism is created by Jan. 1, 2016, the requirements of the law expire.

A minute warning could save lives.

Russell Oliver's partner, Josh Sessoms, said he takes the early warning project personally.

"It may give a minute or two before the earthquake in early warning," he said. "Well, think about that: My kids could be able to get outside of the house and into the street and actually be able to save our lives."

Sessoms just hopes those who control the state's purse strings will feel as passionately about this system as he does.