Elon Musk on engineering: what the evidence says · JRE #1169

What the evidence says 01 / RECORD

Tunneling and earthquake engineering literature broadly supports the premise that underground structures, including tunnels, generally suffer less seismic damage than surface buildings, because they move with the surrounding ground rather than oscillating independently, avoiding the resonant amplification effects that damage above-ground structures; this is the accepted engineering basis for calling tunnels comparatively low-risk in earthquakes. However, "earthquakes are essentially a surface phenomenon" overstates the case: seismic shaking and its damage potential are not confined to the surface, and tunnels and underground stations have suffered severe, sometimes catastrophic, damage in major earthquakes, most notably the 1995 Kobe (Hyogoken-Nanbu) earthquake, when the Daikai subway station's central columns collapsed, causing up to 2.5 meters of surface subsidence, with additional tunnel and station damage occurring elsewhere in the system. Similarly significant tunnel damage occurred in the 1999 Chi-Chi (Taiwan) and 2008 Wenchuan (China) earthquakes, particularly where tunnels were shallow, crossed an active fault rupture, or sat in poor or liquefiable soil. Current engineering consensus therefore treats tunnels as generally lower-risk than surface structures rather than immune, with fault-crossing, shallow depth, and portal/entrance zones identified as continuing points of vulnerability requiring specific seismic design. The claim is best characterized as a misleading oversimplification: broadly consistent with real engineering advantages of underground construction, but its blanket framing elides well-documented cases of serious tunnel and subway damage in large earthquakes.