WFC in severe earthquakes world-wide

A survey of wood frame construction in severe earthquakes world-wide

The survey covers wood frame buildings of all ages and provides evidence of the superior safety of wood frame buildings in severe earthquakes world-wide, including Japan and the United States.

A very high proportion of wood platform frame buildings survived peak ground accelerations of 0.6 g and greater with no collapse or serious structural damage. The resulting injuries and deaths were few. There were very few specific failures, as for example from hillside collapses. Virtually all modern wood frame buildings survived with no visible damage.

Earthquake Richter Magnitude M Estimated number of wood platform frame houses ‘strongly shaken’ Total number of casualties Casualties in wood platform frame houses
Alaska, 1964 8,4 - 130 <10
San Fernando, California, USA 6,7 100,000 63 4
Edgecumbe, New Zealand, 1987 6,3 7,000 0 0
Saguenay, Quebec, Canada 5,7 10,000 0 0
Loma Prieta, California, USA 7,1 50,000 66 0
Northridge , California, USA 6,7 200,000 60 16 + 4*
Hyogo-ken Nambu, Kobe, Japan 6,8 8,000** 6,300 0**

* Foundation failure caused collapse of buildings on hillside. ** Relates to wood platform frame, known as ‘2x4’ houses, in the affected area.

  • The Richter Magnitude Scale M is a commonly used measure of the overall size of the earthquake as determined by the total amount of energy released.
  • The maximum horizontal ground motion generated by earthquakes is measured by seismographs as a fraction of the force of gravity (g).
  • Very severe earthquakes can generate ground motions in excess of 0.6 g, but substantial structural damage can be caused at much lower levels. The Kobe earthquake was measured as high as 0.8 g.
Three undamaged modern wood frame buildings (background) next to an older building (foreground) whose ground floor has collapsed completely, Nishinomiya, Japan. Hyogo-ken Nanbu Earthquake, 1995