There are many parallels between Monday's earthquake and the big one that hit in the Bay Area 21 years ago. Back then, San Francisco's Marina District was hit hard by the Loma Prieta earthquake and the damage caused many people slept outside on the Marina Green.
Today the Marina District is clean, quiet, safe and sound, but do not trust appearances.
"No, you can't take this for granted anymore, no," said Charles Simpson.
Simpson used to be the beat cop in the neighborhood and he remembers the scene two decades ago. Loma Prieta brought to light a neighborhood built on sand and fill very much like parts of Christchurch, New Zealand. Both quakes share one word in common -- liquefaction.
"It amplifies the shaking substantially on orders of multitude," said Roland Burgmann, Ph.D.
Burgmann, a seismologist at U.C. Berkeley, spent much of Tuesday studying Christchurch. This recent quake was an aftershock to a larger one last September, but this one did so much more damage because the rupture occurred directly beneath the city and liquefaction played a role.
"Essentially, it is like the ground falling out beneath you. So you have a building losing its footing and one side slacks down," said Burgmann.
Sound familiar? That was the Marina District in 1989. George Newmount lived through it first-hand.
"And I looked down the streets and saw some houses in the middle of the street," said Newmount.
And as bad as that was, Burgmann warns of worse. The Hayward fault is now well overdue for a 7.0 type quake, give or take a couple of points and around San Francisco, previous generations made a habit of building on fill. They did it in Alameda, on Treasure Island, South of Market, and the Marina. When, not if, the Hayward quake hits, those areas face severe risks.
"Loma Prieta was three times as far from the Marina district as the Hayward Fault is. So the damage would be larger. The earthquake would probably be of similar size, so it would be very bad," said Burgmann.
And in that case, it will not be an aftershock. When the Hayward quake hits, experts predict thousands of deaths of people in the Bay Area and $150 billion in damage.