E a Rt H qU aK e - Background and Introduction

I thought of making the title to this post, "Earthquakes for Dummies", but the thought of offending many who are praying and concerned for us right now wasn't appealing. This recent earthquake in Chile was the first I have ever experienced, so I will include myself as the Dummy or Rookie. :)
This post is the first of several in an EaRtHqUaKe series that will explain what happened during and after the Feb 27th earthquake here in the Temuco area.

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Some Background and Introduction

This recent earthquake in Chile occurred at the boundary between the Nazca and South American tectonic plates. The two plates are converging at a rate of 70 mm per year. The earthquake occurred as thrust-faulting on the interface between the two plates, with the Nazca plate moving down and landward below the South American plate.

Coastal Chile has a history of very large earthquakes. Since 1973, there have been 13 events of magnitude 7.0 or greater. The February 27 shock originated about 230 km north of the magnitude May, 1960 9.5 earthquake in Chile (the largest earthquake worldwide since the beginning of instrumental seismology at the beginning of the twentieth century). The giant 1960 earthquake spawned a tsunami that caused destruction on coasts throughout the Pacific Ocean basin. An estimated 1600 lives were lost to the 1960 earthquake and tsunami in Chile, and the 1960 tsunami took another 200 lives among Japan, Hawaii, and the Philippines.

Approximately 300 km to the north of the February 27 earthquake was the 8.2 earthquake of August 17, 1906. The tsunami associated with the 1906 earthquake produced some damage in Hawaii, with reported run-up heights as great as 3.5 meters.

Approximately 870 km to the north of the February 27 earthquake was the 8.5 earthquake of November, 1922. The 1922 earthquake significantly impacted central Chile, killing several hundred people and causing severe property damage. The 1922 quake generated a 9-meter local tsunami that inundated the Chile coast near the town of Coquimbo; the tsunami also crossed the Pacific, washing away boats in Hilo harbor, Hawaii.

A large vigorous aftershock sequence can be expected from this earthquake. In the time period since the earthquake on Feb 27, 2010 at 3:34 AM, there have been 121 aftershocks of magnitude 5.0 or greater. Eight of these aftershocks have magnitudes of 6.0 or greater. See the Aftershock Map HERE.

Click HERE to read an interesting article about How to Survive a Tsunami - Lessons from Chile 1960.

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Come back for part two...