During the Great Hanshin Earthquake in January 1995, the building was partially demolished. One specific result was that the center span was extended by 1.1 m. (3.6 ft). Despite this, the project was completed on time in September 1996. It is now one of Japan's most popular tourist attractions.
This earthquake, formally known as the "Southern Hyogo Earthquake," caused widespread devastation, including nearly 5,000 fatalities and the destruction of infrastructure. The epicenter was near the Akashi-Kikyo Bridge on Awaji Island's northern edge. However, the bridge escaped with just minor structural damage.
The earthquake occurred at 2:46 a.m. on January 17, 1995. It had a magnitude of 6.5 on the Japanese scale and its depth was 20 kilometers (12 miles). The main shock was followed by several aftershocks, one of which was later determined to be another major quake (with a magnitude of 7.0).
Although the Akashi-Kikyo Bridge was designed to withstand earthquakes, many countries' bridges are not. Therefore, this disaster brought attention to the need for improved seismic safety standards for buildings and infrastructure.
Because the eastern bridge was more likely to be destroyed by an earthquake, the state chose to replace it entirely with a new single-layer span. The new development was approved after more than five years. Construction began in April 2012 and is expected to be completed in 2017 at a cost of $6.4 billion.
The old bridge was considered one of the most innovative designs when it was built in 1974. It had a wide-ranging collection of traffic signals, stop signs, and yield signs that coordinated the movement of vehicles across two decks. One deck was for cars and trucks while the other was for buses and trucks.
The new bridge will be a single layer suspension structure and will connect Oakland to Yerba Buena Island. When it is complete in 2017, it will be the longest continuous truss bridge in the world at about 23 miles long. The main reason for choosing this type of construction is so that they can avoid having to shut down traffic during major repairs. Also, this type of design allows for better integration of transportation systems than a traditional bridge that has separate pathways for vehicles, pedestrians, and bicycles.
The new bridge will be able to handle up to about half the total traffic that uses the existing bridge today.
The Akashi Kaikyo Bridge, which was being built near the epicenter of the earthquake, remained unharmed but was apparently stretched by a full meter due to horizontal displacement along the active tectonic fault. Outside of Japan, the event is often referred to as the Kobe earthquake.
The name comes from where it occurred. Kobe is a city on the eastern coast of Japan's Hyogo Prefecture. The name means "bridge over the river" in Japanese. The Akashi-Kaikyo-Kobe Earthquake occurred at 2:46 AM on January 17th, 1995. It had a magnitude of 7.1 and its depth was 20 kilometers.
The main shock was followed by more than 60 aftershocks measuring up to 4.0 in magnitude. More than 700 people were killed and thousands were injured. Damage totaled about $15 billion at current prices. This makes it one of the most costly natural disasters in history.
The area damaged by the quake includes part of a large rift valley between two mountain ranges. Rifts like this can form when crustal plates underneath Earth's surface slide past each other. They can be vertical, like a well or volcano, or horizontal, like a plain. In this case, the land around Kobe fell about 6 inches toward the rift.
The city rebuilt within five years, but the new buildings were designed to withstand only moderate earthquakes.