Hidden inside the skeletons of high-rise towers, extra steel bracing, giant rubber pads and embedded hydraulic shock absorbers make modern Japanese buildings among the sturdiest in the world during a major earthquake. And all along the Japanese coast, tsunami warning signs, towering seawalls and well-marked escape routes offer some protection from walls of water.

These precautions, along with earthquake and tsunami drills that are routine for every Japanese citizen, show why Japan is the best-prepared country in the world for the twin disasters of earthquake and tsunami  practices that undoubtedly saved lives, though the final death toll is unknown.

In Japan, where earthquakes are far more common than they are in the United States, the building codes have long been much more stringent on specific matters like how much a building may sway during a quake.

After the Kobe earthquake in 1995, which killed about 6,000 people and injured 26,000, Japan also put enormous resources into new research on protecting structures, as well as retrofitting the country’s older and more vulnerable structures. Japan has spent billions of dollars developing the most advanced technology against earthquakes and tsunamis.

Japan has gone much further than the United States in outfitting new buildings with advanced devices called base isolation pads and energy dissipation units to dampen the ground’s shaking during an earthquake.

The isolation devices are essentially giant rubber-and-steel pads that are installed at the very bottom of the excavation for a building, which then simply sits on top of the pads. The dissipation units are built into a building’s structural skeleton. They are hydraulic cylinders that elongate and contract as the building sways, sapping the motion of energy.

Of course, nothing is entirely foolproof. Structural engineers monitoring the events from a distance cautioned that the death toll was likely to rise as more information became available. Dr. Jack Moehle, a structural engineer at the University of California, Berkeley, said that video of the disaster seemed to show that some older buildings had indeed collapsed.

The country that gave the world the word tsunami, especially in the 1980s and 1990s, built concrete seawalls in many communities, some as high as 40 feet, which amounted to its first line of defense against the water. In some coastal towns, in the event of an earthquake, networks of sensors are set up to set off alarms in individual residences and automatically shut down floodgates to prevent waves from surging upriver.

Critics of the seawalls say they are eyesores and bad for the environment. The seawalls, they say, can instill a false sense of security among coastal residents and discourage them from participating in regular evacuation drills. Moreover, by literally cutting residents’ visibility of the ocean, the seawalls reduce their ability to understand the sea by observing wave patterns, critics say.

Waves from Friday’s tsunami spilled over some seawalls in the affected areas. “The tsunami roared over embankments in Sendai city, washing cars, houses and farm equipment inland before reversing directions and carrying them out to sea,” according to a statement by a Japanese engineer, Kit Miyamoto, circulated by the American Society of Civil Engineers. “Flames shot from some of the houses, probably because of burst gas pipes.”