Japan sits on a seismically active zone, so earthquake preparedness runs deep in the country’s culture. As a result, Japanese properties are built to a complete set of earthquake resistance standards. Different standards can withstand different magnitudes of earthquake, so they carry different value in the market and have a clearly different bearing on residents’ safety. This article introduces Japan’s earthquake resistance standards to help reduce investment risk.
Japan’s Earthquake Rating System
Japan uses the Japan Meteorological Agency (JMA) seismic intensity scale, rather than the more familiar Richter magnitude scale — a rating system unique to Japan. It has ten levels, with 7 as the highest. The 2011 Great East Japan Earthquake measured a seismic intensity of 7.3 on this scale, which corresponds to JMA intensity level 7, or magnitude 9 on the Richter scale. Japan’s earthquake resistance standards for property are therefore expressed using the JMA seismic intensity scale.
Source: Japan Meteorological Agency, explanation of seismic intensity
https://www.data.jma.go.jp/multi/quake/quake_advisory.html
Japan’s Building Standards
Japan has long prepared for natural disasters, and its Building Standards Act does not address earthquakes alone — its provisions require buildings to withstand load, wind pressure, water pressure and other external forces. Any building over 60 meters tall must comply with the technical standards set out in government ordinances for the structural methods needed to ensure building safety, and the pressure and deformation that each part of the structure will experience under load and external force must be calculated and its effect on the structure assessed; the design is then certified by Japan’s Minister of Land, Infrastructure, Transport and Tourism. Buildings of 60 meters or less must likewise account for the pressure and deformation caused by external forces, and must either receive the Minister’s approval or use a method designated by the Minister. Every building must obtain a “building confirmation certificate” (建築確認済書) before construction begins, confirming government approval that the design complies with the Building Standards Act.
Japan’s Earthquake Resistance Standard
Japan’s earthquake resistance standard refers specifically to the seismic-resistance requirements for buildings set out in the Building Standards Act, and that Act has been amended repeatedly over the years to raise those requirements. Following the 1978 Miyagi earthquake, the Japanese government revised the Building Standards Act, adding a new standard on top of the previous seismic design requirements. The new law formally took effect on June 1, 1981. Under the new earthquake resistance standard, newly built buildings must be able to withstand an earthquake of JMA seismic intensity level 6–7, whereas the old standard only required buildings to withstand level 5. Buildings meeting the new standard therefore offer owners significantly better protection for life and property. After the 1995 Great Hanshin earthquake, the Japanese government again revised the Building Standards Act, raising the earthquake resistance requirements for wood-frame construction; this revision took effect on June 1, 2000. As a result, wood-frame buildings built after June 2000 are more earthquake-resistant than those built before 2000.
Things to Watch For
The new earthquake resistance standard was set on June 1, 1981, but that does not mean every building completed after 1981 meets the new standard. The new standard is tied to the date a building confirmation certificate was issued — in Japan, a building confirmation certificate must be obtained before construction can begin — so some buildings received their certificate before 1981 and began construction then, but were only completed after 1981. For buildings completed around 1981–1982, buyers should check carefully whether the building falls under the new or the old earthquake resistance standard.
It is also worth noting that the earthquake resistance standard has no necessary relationship with a building’s structural type. A wood-frame house built after 2000 meets the new earthquake resistance standard, while a steel-reinforced concrete (SRC) building completed before 1980 may still only meet the old standard. Japanese buildings are mainly built using one of four structural types — wood (W), steel frame (S), reinforced concrete (RC), and steel-reinforced concrete (SRC) — but the structural type alone does not determine earthquake resistance; an SRC building is not necessarily more earthquake-resistant than an S building. As construction technology advances and higher-strength concrete and other new techniques become available, a building’s earthquake resistance can improve regardless of its structural type.
Have a question about this guide? Leave a comment below, or ask Zagdim directly.
Your first stop for international property and global living.
Research and insights. Know what’s changing. Understand what matters.
