While most of the country isn't situated right on an earthquake fault, a whole lot of the country is subject to shaking from quakes in other states. Whether you're near a volcano zone and get little volcanic tremors now and then, in an area subject to a lot of fracking and its related quakes, or in an area where the soil is level, flat, and ready to liquify after a strong midwestern quake one state over, it's a good idea to ensure your tower crane does not tip over in a quake. If you are new to the construction industry and have just started working in a new town on a site that needs to take quake shaking into account, and you've never had to deal with that before, here's what your co-workers and the crane rental company will do.
Bedrock and Platforms
Tower cranes need to be steady to withstand wind and swaying from heavy loads even on good days, so the crane will already be attached to a concrete pad on level ground. That pad, in turn, should be bolted into the bedrock under the soil on the site. The soil itself needs to be stable; if the soil shifts or erodes during a rainstorm, for example, the crane's weight can cause the concrete pad section over the now-eroded zone to crack. If rain does become a problem during the construction phase, always check around the pad after the rain to see if there are signs of erosion, such as water running out from beneath the platform.
You'll also see that the crane has to be attached to the building itself as the building's stories are completed. Every few stories, you should see another connection to the tower crane; if you don't, ask the foreman what's happening. Obviously, if the building is only one or two stories, you might not see these. But you should see them once you get into skyscraper territory.
What You Yourself Can Do
Cranes sway in wind, so the swaying from a quake isn't going to be that much different. Still, if a quake hits, take the crane into consideration. Try to move away from the crane, but watch out for flying broken glass first. Crane accidents do happen, and in 2002, two tower cranes attached to a building collapsed during a strong quake in Taiwan. But that is a rare occurrence, with the majority of cranes doing just fine during shaking.
If you have other questions about how to secure a crane and prevent problems during a quake, talk to your site foreman or a more experienced worker. You can also talk to the people at crane companies to see what they recommend for their cranes.