Dry stone fixtures are those that use stone blocks but no mortar to create a sturdy wall, hedge, or pathway. This is a very old type of construction that gives the structure a rustic look, and it's been used in cultures around the world for centuries. But the lack of mortar means that there's nothing really holding the stones together except for amazing puzzle-solving skills. So if you live in a quake zone, as so many residents of the country do, can you still have this type of structure in your yard?
Wedges vs. Blocks
You actually can, depending on the construction. A study in Soils and Foundation looked at how the shape of the stones used affected the structure's ability to stay standing in a quake. Wedge-shaped stones tended to have better quake resistance than blocky stones, and the researchers found that this had to do with surface area. Wedge-shaped stones had greater interlocking surface area, which created more friction. The researchers also noted that dry stone masonry structures had withstood several historically strong quakes around the world.
The wall or fixture, if constructed carefully, will have a very tight fit. The one exception is a type of wall found in high-wind areas; these walls have spaces between the stones to allow that strong wind to flow through. But assuming wind isn't an issue for you, the tight fit, with stones filling every space, helps stabilize the wall against movement.
Weight Plays a Role
The weight of the stones also helps keep the wall standing in the event of shaking. Like any structure, an extremely strong quake could have an effect, but in many cases, the weight of the wall helps keep the blocks stationary. The shape also plays a role; these walls tend to be a bit wider at the base than at the top.
If you live in a quake zone and want to have a dry stone wall or other fixture, talk to a local company that knows what the risks in your area are like. Also keep in mind that the state of the soil in your own yard may affect the stability of the wall, but the stone company can help you figure out your next steps if that's the case. There's usually a solution if an issue like that appears. You may be pleasantly surprised at the options available to you.