According to a new study, buildings in Liechtenstein dating from the Middle Ages are better able to endure earthquakes than their modern counterparts as a direct result of an antiquated structural feature
The aftermath of 5.4 magnitude earthquake which rocked the Liechtenstein town of Balzers in 2012 drew the attention of Maria Brunhart-Lupo, a geologist from the Colorado School of Mines who also happens to be a native of the region.
Balzers is situated in an earthquake prone region, where the tectonic interactions which led to the creation of the Swiss Alps continue to trigger seismic disturbances. The town is beset by two unnoticeable tremors a day on average and is occasionally hit by stronger, more pernicious earthquakes.
Following the 2012 earthquake, Brunhart-Lupo noticed that the amount of damage sustained by the town’s buildings varied significantly depending upon their vintage. Modern buildings were more seriously damaged, suffering from cracked walls, shattered windows and broken balconies. The town’s older, more historic buildings, however, managed to weather the earthquake largely unscathed.
In order to ascertain the reason for this heightened resilience, Brunhart-Lupo conducted a structural assessment of the Gutenberg Castle – one of the most venerable buildings in Balzers, as well as one which remains free of recent additions.
Brunhart-Lupo’s conclusion, which she revealed to an annual meeting of the Geological Society of America in November, was that the reason for the enhanced earthquake resistance of Gutenberg is the absence of any structural features connecting the floor of the castle to its walls.
The first floor of the castle was used to keep livestock when it was initially built, and thus kept as an open air structure without any connection to the surrounding walls in order to ensure sufficient ventilation. This absence of a connecting structure enabled the walls to move independently of the floor.
Over the centuries, the building penetrated deeper into the sedimentary layers of the ground via the process of settlement, thus producing a deep and stable foundation. This in turn meant that in the event of earthquakes the older buildings would actually stabilize instead of being buffeted from side to side like modern structures.
With contemporary buildings, the walls are attached on all sides, which means that forces which act upon the foundations have a negative impact upon the walls.
According to Brunhart-Lupo, the increased structural integrity of the older buildings serves as proof that the latest engineering methods are not always applicable in all contexts, and that in certain geographic circumstances, more venerable techniques can save the day.