Tokyo (CNN) -- A brief video clip released Saturday captures the massive tsunami that crippled Japan's Fukushima Daiichi power plant, showing the wall of water that slammed into the facility and created an ongoing crisis.
The video shows the giant wave generated by the historic March 11 earthquake crashing over the plant's seawall and engulfing the facility, with one sheet of spray rising higher than the buildings that house the plant's six reactors. Tokyo Electric Power, the plant's owner, told reporters the wall of water was likely 14 to 15 meters (45 to 48 feet) higher than normal sea levels -- easily overwhelming the plant's 5-meter seawall.
The footage was was shot from high ground about 900 meters south of the plant by a worker who evacuated before the tsunami hit, the Tokyo Electric Power Company said in releasing the six-second clip.
Photos released by the company showed shattered windows, scattered papers and dangling ceiling tiles throughout the plant's now-empty office annex. Two workers were killed in the basement of the No. 4 reactor's turbine plant when the tsunami struck, and their bodies were recovered only last week.
The tsunami knocked out generators and pumps needed to cool the plant's three operating reactors following the magnitude 9 earthquake, leaving engineers struggling to prevent a bigger disaster as those units radioactive cores overheated. In response to the quake, Japanese regulators issued tougher standards for emergency power at nuclear plants Saturday.
Power stations will be required to have two diesel generators as backup power for each reactor unit, said Hidehiko Nishiyama, the chief spokesman for Japan's Nuclear and Industrial Safety Agency. Current regulations require only one generator per unit.
At the plant, workers are beginning to lay ground-level pipes between the reactor units and the radioactive waste treatment facility where engineers hope to pump the contaminated water that has been building up, Sakae Muto, the head of the utility's nuclear power division, said Saturday.
Workers have been pouring hundreds of tons of water a day into the reactors in an effort to keep them cool until normal circulation systems can be restored. The No. 2 reactor is believed to be leaking highly radioactive water, some of which had been spilling into the Pacific until Wednesday, while flooded basements in the turbine plants of all three units are making it impossible to restore power, company officials said.
And engineers have been adding nitrogen into the primary containment shell around reactor No. 1, a move aimed at countering a buildup of flammable hydrogen in the unit. The inert nitrogen displaces oxygen that could fuel an explosion, like the hydrogen blast that blew apart the buildings surrounding units 1 and 3 in the days following the earthquake.
Hydrogen buildup is a symptom of damaged fuel rods in the cores of the reactors. But Tokyo Electric has called the chances of another explosion "extremely low." And new equipment allowed engineers to raise the concentration of nitrogen from 98 percent to 99 percent Saturday, Nishiyama said.
Workers returned to the plant Friday following a magnitude 7.1 aftershock late Thursday night that forced them to evacuate for about eight hours, Japanese authorities said. The aftershock is not believed to have inflicted any further damage to the plant, Tokyo Electric and the safety agency reported Friday.
Hiroo Saso and Gen Shimada contributed to this report for CNN.