San Francisco City Hall after the Great San Francisco Earthquake

From the U.S. Geological Survey (USGS):

San Francisco City Hall — For our #TBT we're sharing a photo from San Francisco City Hall after the Great San Francisco Earthquake on April 18, 1906 (9 days from now...and, of course, almost 109 years earlier). After the earthquake and fires, the building was reconstructed with a new design and slightly smaller footprint. After the 1989 Loma Prieta earthquake the building was retrofitted with a seismic base isolation system which essentially helps separate the main building from the substructure below it, using flexible rubber bearings or pads, in order to absorb much of the shaking from an earthquake rather than that motion moving upwards into the building itself. This doesn't make the building "earthquake proof" but it can significantly lower the amount of damage.

You can learn more about about earthquakes and earthquake preparedness at http://earthquake.usgs.gov/learn/

#USGS #science #earthquakes #ThrowBackThursday#SanFrancisco #buildings #architecture #preparedness#naturalhazards #California #history #historical