Tunneling | InSAR for Early Warning | Precursory Motion

Mexico City Metro Overpass Collapse
Source: https://newsmediacity.com/mexico-city-metro-overpass-collapse-live-news-and-updates/

Background: Since the inauguration in 2012, the L12 Mexico City Metro has been closed many times due to malfunctions, deterioration and repairs. In 2014, 11 out of the 20 stations were closed due to failures which were then repaired after the 2017 earthquake. Read more

Project overview: After the catastrophic collapse of the L12 Mexico City Metro on May 3, 2021, the TRE Altamira team performed an InSAR analysis to determine whether it was possible to detect precursory motion of the structure.

Olivos station

InSAR Analysis

For the study, we used high-resolution satellite radar images and our advanced SqueeSAR® algorithm. We processed 40 TerraSAR-X images acquired over Mexico City from February 2020 to April 2021. This dataset allowed us to identify about 170,000 measurement points over the viaduct and the surrounding area.

Motion Detection

The largest rates of motion show strong spatial correlation to the collapsed section of the metro. The time series of displacement highlights trend changes since the end of 2020, with rates increasing in the months prior to the event. The collapsed area is also clearly identifiable when displaying the acceleration value of each measurement point.

Cumulative displacement map with time series

L12 Mexico City Metro - Olivos Station - Velocity and Acceleration Maps

Conclusion: For the L12 Mexico City Metro analysis, satellite monitoring with SqueeSAR® provided valuable information for the detection of early warning and proves InSAR’s potential for the future of early warning systems. In urban environments, where the processing of high-resolution satellite imagery with SqueeSAR® can identify hundreds of thousands of measurement points, we are able to precisely assess the stability of manmade structures such as viaducts and the surrounding area over time.