MAGNITUDE AND EPICENTER
Great Hanshin earthquake occurred at 5:46 a.m. on Tuesday, January 17,
1995. This earthquake is also called by the following names: Kobe,
South Hyogo, Hyogo-ken Nanbu.
earthquake had a local magnitude of 7.2. The duration was about 20
seconds. The focus of the earthquake was less than 20 km below
Awaji-shima, an island in the Japan Inland Sea. This island is near the
city of Kobe, which is a port city.
earthquake was particularly devastating because it had a shallow focus.
The earthquake had a "strike-slip mechanism." The resulting surface
rupture had an average horizontal displacement of about 1.5 meters on
the Nojima fault. This fault which runs along the northwest shore of
The earthquake caused 5100 deaths, mainly in Kobe.
The Hanshin earthquake was the worst earthquake in Japan since the 1923
Tokyo earthquake, which is also called the Great Kanto earthquake. The
Great Kanto earthquake claimed 140,000 lives.
On the other hand, the Kobe region was thought to be fairly safe in terms of seismic activity.
cities of Kobe and Osaka are connected by an elevated highway. The
earthquake caused several portions of this highway to collapse.
of the deaths and injuries occurred when older wood-frame houses with
heavy clay tile roofs collapsed. Note that homes and buildings are
designed to be very strong in the vertical direction because they must
support their own static weight. On the other hand, buildings can be
very susceptible to horizontal ground motion.
Furthermore, many of the structures in Kobe built since 1981 had been
designed to strict seismic codes. Most of these buildings withstood the
earthquake. In particular, newly built ductile-frame high rise
buildings were generally undamaged.
Unfortunately, many of the buildings in Kobe had been built before the development of strict seismic codes.
collapse of buildings was followed by the ignition of over 300 fires
within minutes of the earthquake. The fires were caused by ruptured gas
lines. Response to the fires was hindered by the failure of the water
supply system and the disruption of the traffic system.
seismology professor Tsuneo Katayama wrote that he "had opportunities
to observe the damages caused by the 1989 Loma Prieta and the 1994
Northridge earthquakes." However, he thought that Japanese structures
would not collapse as U.S. structures had in those earthquakes.
Katayama also wrote, "While our country was having a bubbling economy,
we Japanese forgot to pay due attention to mother nature."