At about 4:30 a.m. on January 17th, 1994, the first P-waves of an earthquake, travelling at 12,000 miles an hour, snaked below the earth's surface and struck the Northridge Meadows apartment building near Los Angeles, California. Like thousands of other similarly constructed buildings here, it was a stucco-type low-rise complex with units built over a garage.
A few seconds later the violent S-waves hit the 164-unit building, causing it to collapse. Sixteen people were crushed to death.
The death toll of the 1994 quake in Los Angeles was only 72, quite small when compared with the Armenia earthquake which killed 25,000 people three years earlier, or the one in Kobe, Japan, which killed 6,000 people a year later.
But with 12,00 people injured in Los Angeles, 437,000 homes damaged, $42 million in damage, and insurance claims which reached $15 billion in an area that had prided itself on earthquake preparedness, engineers and city planners went back to the drawing boards.
Each time there is a major earthquake, planners learn more about how buildings will fare in a direct hit. But the scientific research is difficult, particularly in predicting the complex interaction of various quake pulse waves with silt, soil and rock.
"How can we claim to build for events that might happen in the next 1,000 years when our ideas don't hold up for 20 years?" seismologist Thomas Heaton asked Los Angeles author Mike Davis in 1995. "I am sorry, but the warranty on that research expired last year?"
California's building codes have been regularly revised since 1933, when the Long Beach quake killed 120 people. It was updated after a major quake in 1971, and again in 1994.
Innovations have included the construction of so-called shear walls, normally made from plywood fastened between upright wooden beams that help withstand side-by-side forces. After 1994, many homeowners also bolted the frames of their homes to the concrete foundation to prevent the home from slipping away.
Kaufman and Broad, the largest home-builder in the western US, says that complying with the latest Los Angeles building codes adds between $2,500 and $4,500 to the building cost of a typical 2,000 sq ft house.
Existing homes, especially older buildings made of unreinforced brick, can also be modified at varying costs. Generally, steel rods are put between walls, and between each story of a house. Walls around homes made from concrete block are also retrofitted with steel rods.
But even those measures are limited. The most dangerous structures in Los Angeles, experts agree, are the massive precast concrete shopping malls, multi-car garages, discount stores and factories. Little has been done to retrofit those structures. If an earthquake hit during the day when those structures were occupied, fatalities would be huge.
Specialists also point to the disturbing fact that no populated area of Los Angeles has never been the direct epicentre. Even the epicentre of the Northridge quake was in the mountains.
When you're right up within a mile of a really big fault, you have really big movements, Ms Lucy Jones, chief scientist for the US Geological Survey in southern California told Associated Press. "That level of movement hasn't been incorporated into the building codes. How bad will it be? We really don't know."
US warships steamed to Istanbul as the US military mobilised medical teams and firefighting aircraft to help the Turkish authorities. A US military crisis response team was due to arrive in Istanbul from Naples with doctors and others experts trained to assess medical needs.
The US Air National Guard is sending three C-130 aircraft equipped to fight forest fires. A US Navy helicopter carrier the USS Kearsarge, and two other ships designed for amphibious operations left Spanish ports on Tuesday for Istanbul.