A Case of Derailment and Overturning Caused by the 1994 Northridge Earthquake and Its Analysis with Microtremor

Yutaka NAKAMURA, Jun SAITA
On January 17, 1994, the Northridge earthquake attacked Los Angeles. Though this earthquake is not so large (M_s=6.8), it damaged many structures as railroad, freeway and many buildings and lifelines as water and gas systems because it occurred just below the city area. We went to the area to investigate the damage and measure microtermor at and around damaged area. Here we report the state of railway damage as derailment and overturning, and the ground motion characteristics with microtremor. We estimate a shear strain of surface ground at the time of the earthquake and it seemed to be large at the derailment point.