Tilt meters have been used in the United States for decades. In some states, such as New Mexico, it is even required by law to place them around wells . Insurance companies also sometimes require tilt meters to be placed in their insured properties around construction or drilling sites. This is to capture any soil movement and damage.
Complex construction project
For the first time, tilt sensors from Groningen are now being used in a complex new construction project on the West Coast. In downtown San Francisco, a 300-meter-high skyscraper is being built right next to a landmark building with a very deep parking garage underneath. The property owner is concerned about the risk of damage from this construction work.
Relationship to earthquakes
San Francisco is an earthquake zone and undergoes many quakes every year. In the process, there is weak subsoil in some locations. Tiltmeters show in Groningen that low-frequency (LF) quake waves can be captured well.
In Groningen, these LF waves roll across the land for many tens of kilometers during quakes. This causes objects to rotate. By measuring continuously, any damages caused by construction activities and earthquakes can be named separately.
After the USGC (US Geological Services) expressed its admiration and interest in the StabiAlert measurement data of Groningen quakes, as well as observed intercontinental quakes, contacts were made by a monitoring company in San Francisco. In recent months, much of the measurement data has been discussed with American experts. On the night of January 8-9 was the final discussion about the assignment. This included the data from the Zeerijp quake on Monday, January 8. This was the deciding factor for the client to choose the Groningen company StabiAlert.
Three years of continuous monitoring
The client has chosen to be the first to equip a landmark building in downtown San Francisco with 8 tilt sensors. StabiAlert will provide real-time monitoring there for the next 3 years.