High, Dry and Safe: In Search of the Perfect Site
The ideal spot for a seismic station is dry, quiet and safe from vandals and thieves. Seismometers record slight ground motions, allowing them to hear distant (and not so distant) earthquakes. But cars or even kids playing near a seismic station can produce ground vibrations that overwhelm the subtle sounds of earthquakes. Seismic stations include plenty of expensive, high-tech instruments that are worthless to the average person. But they also contain mundane items that can be useful, such as 12-volt batteries and insulated wiring, making theft a problem. And water is the enemy.
Malawi presented novel challenges for siting our stations. Our first priority was to find dry, secure locations to prevent damage and loss. As we drove into the Karonga region for the first time, our hearts sank; the epicentral region is low-lying and wet, small villages surrounded by rice paddies. Our arrival during the rainy season did not help.
But with a little hunting, we were able to find high and dry spots for most of our stations. We bumped along narrow village tracks in our rented 4×4, occasionally getting stuck on particularly muddy sections. Most of the dirt roads did not appear on our outdated maps, so we stopped regularly to ask for directions. When our Malawi colleagues explained that we were there to learn about the chindindindis (Tumbuka for earthquakes), they were eager to help!
In many parts of the world, safety and quiet can be achieved simultaneously simply by deploying stations in the middle of nowhere. This is not an option in densely populated Malawi, where one farming village abuts another. Main thoroughfares and small dirt roads alike were crowded with kids walking to school, villagers biking to town, and farmers grazing their goats and sheep. Instead, we sought out village police, teachers, and other officials for help finding safe spots. In some cases we hired guards to look after them.
We spent hours driving, inspecting sites and waiting to meet with officials. We normally skipped lunch, fueling ourselves instead on passion fruit-flavored Fantas and “puffs” (kids junk food akin to cheese doodles). But these efforts paid off – we found good sites for our equipment and started listening.