In the wake of the mid-October Hawaii quake, scientists are not sure whether the >6 aftershock was an aftershock, or an independent earthquake. The first quake, which was measured at 6.7 on the Richter scale occurred at 7:07 A.M. at a depth of 24 miles; the second quake was measured at 6.0 on the Richter scale, and occurred at 7:14 A.M. about 12 miles from the first quake, and at a depth of 12 miles.

As mentioned in the previous post, earthquakes are common on Hawaii, but humans cannot feel most of them. Seismographs measure their occurrence. The map below shows the distribution, and magnitude of earthquakes over a 25-year period of time (1962 – 1985). As can be seen, quakes higher than 6.0 are less frequent than the smaller 2.0 quakes.

The October 2006 quakes were the largest that Hawaii had felt in many years. We can’t do very much about preventing earthquakes; but we can be prepared. One of the most important things that we can do is build structures that are designed to withstand the energy created by earthquakes. Quakes in 5.0 to 6.5 ranges are powerful, but good building standards can reduce damage, and prevent widespread loss of life. Quakes that are greater than 7.0 are extremely powerful, and likely will cause widespread damage. In every instance of an earthquake, moving to a secure area is the most important thing we can do.

The maps below show the distribution of aftershocks for the October 15th quake. Note the two very large quakes (shown in the large circles), with many smaller aftershocks ranging from 1.7 to 4.0. To interpret the Richter scale, every time the magnitude increases by 1, the energy is 10 fold. So a 4.0 quake is ten times are energetic as a 3.0, and 5.0 is 100 times greater than a 3.0.

An important citizen response to earthquakes is to learn about them. Not only where you live, but to where you often travel. You might want to check out The Global Earthquake Response Center to learn more about quakes, and what knowledge is of most worth. If you are planning a trip to Hawaii, continue on. You might just want to be a little more knowledgeable about paradise’s earthquakes, and volcanoes. Also, if you are on the Island of Maui, you might want to check out the bicycle trip in which you bike down the island’s volcano, from the very top to the ocean below. And a stop halfway down for lunch, it can’t be beat. And best of all, they take you up to the summit in a van!