You can go 10+ years without a big earth quake in CA, so people get lazy, stop strapping their hot water tanks to walls, stop nailing bookshelves against walls, etc...
Also - not all buildings are earthquake proof - only modern ones. Older ones can still fall down fairly easily.
Finally - when push comes to shove (pun intended), a 6.0+ is just going to do a lot of damage regardless of your precautions - particularly around store shelves, roads, etc...
The other thing I think people don't often understand (or appreciate, or respect) is that the richter scale is logarithmic.
A 7.0 isn't just a little bit worse than a 6.0. It's 10 times worse. And an 8.0 is 100 times more powerful than a 6.0.
So we're not too terribly concerned with these smaller quakes, even if 6.0 is still pretty big. The one we worry about is hundreds of times more powerful. There are some levels of energy you simply can't prepare for.
"The temblor struck about six miles south of Napa around 3:20 a.m., according to the United States Geological Survey. It was the most powerful earthquake to hit the Bay Area since the Loma Prieta earthquake of 1989, which collapsed a section of the Bay Bridge. The shaking was felt over an area that encompassed hundreds of miles.
The earthquake threw much of the Napa Valley — normally an edenic retreat famed for its wine and fine dining — into chaos of falling glass and collapsing bricks. Dozens of water and gas mains were ruptured, and at least six fires broke out, including one in a mobile home park that destroyed four homes and damaged two others. Thousands remained without power."
Now, can you imagine what a 10x more powerful earthquake at 7.0 would do? (Roads, Bridges, and Buildings collapsed).
An 8.0 would be so catastrophic that deaths would be in the hundreds, and damage would be horrific.
It's not just the buildings themselves but the ground they're built on. Many areas in the Bay Area are built on land fill (like areas of SF) or bay bottom soils. When a big earthquake hits, this kind of soil liquifies, amplifying the motions caused by the quake, destroying anything build on top of it if not anchored into bedrock.
I totally agree it's possible to be prepared, but if you're talking about the earthquake I'm thinking about from May - http://earthquake.usgs.gov/earthquakes/shakemap/global/shake... - I don't think it's a great example, since the epicenter was pretty far from central Tokyo and also quite deep (153km) so at the surface it wasn't particularly strong.
Apart from being centered very close to Napa this earthquake was also fairly shallow (10km) so it was significantly more intense (albeit in a small, not heavily populated area) even though it was of the same magnitude. http://earthquake.usgs.gov/earthquakes/shakemap/nc/shake/722...
(I say that based on the numbers, not having first-hand experience with either quake)
I'm not arguing that you can't prepare for this - but a 6.0+ is just going to do a lot of damage, regardless of how much you prepare. Roads will be torn apart, older buildings will shatter, fires will be started, etc...
Preliminary reports put the damage to in California in the neighborhood of $1 Billion.
It's important to repeat that this was the biggest earthquake the Bay Area (an area that certainly gets its share of earthquakes) has seen in 25 years.
It helped that my TV included a little kit (containing cords, brackets, and screws) and instructions for securing it. It felt like just another step in the physical setup of the TV, not something I had to do "eventually."
Also - not all buildings are earthquake proof - only modern ones. Older ones can still fall down fairly easily.
Finally - when push comes to shove (pun intended), a 6.0+ is just going to do a lot of damage regardless of your precautions - particularly around store shelves, roads, etc...