An Earthquake Primer

The third next most disastrous earthquake in  Japanese history (behind Tokyo 1923 and Tokaido 2009) was the Great Hanshin Earthquake, which occurred at 6:46 am on January 17, 1995 killing over 6000 people, mainly in Kobe and nearby cities.

 Damage from earthquakes comes from at least three sources.
1. Ground Motion. Movement of the ground causes collapse of building and bridges, breaking of power lines and pipelines as well as other structural damage. Fires caused by ruptured gas lines are also a major hazard, especially since waterlines are often broken and fire fighting becomes difficult.
2. Ground Failure. Earthquakes often cause landslides. Also, liquefation may occur as soil particles are jarred and water seeps in. Buildings topple or sink on such liquefied soil.
3. Tsunamis. These waves, sometimes incorrectly called tidal waves, occur when the epicenter is undersea or very near the ocean and travel as a shock wave from the epicenter. Tsunamis can travel at speeds up to 1000 km/h (620 mph) and as they reach shore, they can mount up forming waves 15 m (49 ft) tall and cause severe damage to coastal regions. (The Kobe quake generated no tsunamis.)

 Photos below depict some of these types of damage. They were taken either about a month after the quake or about two months afterward, when I briefly went as a volunteer to help out with the Baptist relief effort.


Ground Motion and Structural Collapse

Wood frame buildings were often reduced to rubble in the area of greatest ground motion.

Many steel frame, or reinforced concrete buildings fared no better. This is Kobe city hall building with the entire 5th (?) floor collapsed.

The collapse of the tram rail line to man-made Rokko Island (where our son was stranded for 2 1/2 days) was just one example of the way in which earthquakes paralyze traffic, confounding the problems of rescue, fire fighting, and other forms of relief.

As you probably saw on TV, a portion of the Hanshin Expressway also collapsed. This segment remained standing, but, as you can see, was probably very near collapse.
Ground Failure and Liquefaction
Liquefaction occurs with excessive shaking of soil that has a high water content, turning the soil into a liquid state.

Here you can see mud covering the cobblestone walkway on Rokko Island. When my son and I returned to Rokko Island, we had to fight our way through many mud patches like this.

With liquefaction, the soil sinks. The row of planters in the distance was straight across before the earthquake. In the center of the island (where this photo was taken), the soil had only sunk 6" to one foot. However, nearer the outer edges, it had clearly sunk 3 to 4 feet. Where the soil was supported (as around this building, which probably has a pylon-foundation), no sinking was seen. (Yes, that's Wesley, our then 15 year-old son).
Fire

A tremendous percentage of the deaths occurred due to the fires that followed the earthquake.

Our former language teacher lost her mother in a neighborhood much like this one.
Volunteers!

A group of Baptist volunteers serving a hot meals to those living in temporary shelters just after the earthquake.

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