I got the news early in the morning while checking my email before I crawled out of bed. One line an 8.5 (original calculation before all readings were in) earthquake has hit Japan, tsunami warnings have gone out across the world.
Whoa, not something you expect to wake up to. I didn’t realize how bad anything was though until videos, pictures and news reports started pouring in throughout the day. How scary. You only have moments to acknowledge and then react to what is happening around you. I’m so sad for them right now.
I reached out to the Curator and Geologist at the Tellus Science Museum in Cartersville, Julian Gray, to ask some questions that were on my mind about Earthquakes that I was unaware of.
Describe to me what an 8.9 earthquake would feel like in Ga.
An earthquake of that magnitude would be devastating in Georgia. Because we are in a region with few large earthquakes, buildings in Atlanta are not engineered to withstand large earthquakes. Many buildings would collapse or be seriously damaged. It would be difficult to walk or stand. Roads would be damaged and bridges would collapse. If such a thing were to take place, it would be catastrophic – as it would be anywhere.
What are some of the differences between the Earthquake in Japan and the Earthquake in Haiti
The Haiti earthquake was magnitude 7.0 and the Japan Earthquake was 9.0 (The U.S. Geological Survey has revised their magnitude calculation.) Also, the Haiti earthquake and aftershocks occurred on land or under or near a major city. The city of Port Au Prince was almost leveled because of the closeness of the epicenter. Also, since Haiti is an economically poor country, buildings were not constructed to withstand powerful earthquakes. Although the Haiti earthquake was not as powerful, the combination of the location of the epicenter and poor building construction made matters much worse than in Japan on March 11. Also, the majority of the damage in Japan was from the tsunami.
How can you tell the difference between an earthquake and an Aftershock?
Aftershocks are earthquakes. We call some earthquakes aftershocks because they occur after a major earthquake. There was a magnitude 7.2 earthquake in Japan on March 9. This was followed by three earthquakes of magnitude 6. Initially, the M7.2 was called the main earthquake and the three M6 earthquakes were called aftershocks. Then the big M9.0 earthquake struck. The M7.2 and three M6 earthquakes were then reclassified as foreshocks, earthquakes that lead up to the main event. Aftershocks are earthquakes that occur after a major earthquake and are of a lower magnitude. There have been more than 400 aftershocks from the March 11 earthquake in Japan! They may go on for months.
Why do Aftershocks happen?
In general, earthquakes occur because stress is building in the earth’s crust. This happened at places like Japan and California because two crustal plates are moving in opposite directions and pushing against one another. When the stress is released, it does so violently, but often not all at once. They lurch forward rather than slipping gently. The earth may begin to release built-up stress in foreshocks, then have one large earthquake, and then numerous aftershocks to reduce remaining residual stress.
Does it seem like more and more earthquakes are happening? Or is the media impact that we have nowadays made them seem higher.
There are no more or fewer earthquakes occurring now than at any other time in history. We are hearing about them because we now have seismographs in more places and we have built more cities on fault zones. Statistically, there is the same number of earthquakes as at any other time. The largest earthquakes in history have been recorded in the last 100 or so years. Why? Because we now have seismographs to detect them!
Do Earthquakes happen in GA?
They do, but they are much smaller than earthquakes in other parts of the world. They are generally magnitude 2 or 3. These earthquakes are difficult to feel unless you are sitting very still. Most people who feel these earthquakes say that it feels as though a heavy truck drove by their house.
Do you think we (GA) will ever have a catastrophic earthquake like Japan?
Most likely not. We live in an area where the earth’s crust is not pressing against another part of the earth going in a different direction. However, earthquakes do occur in odd places. In 1886 a powerful earthquake struck Charleston, South Carolina, an area that scientists would not normally expect to experience such things. We live on a dynamic planet. Although we are not in a seismically active area, we’re moving to the west, along with the rest of North America, at about an inch a year. Occasionally some odd build-up of stress may occur and the Earth releases that stress, wherever it may be, violently. Could happen, but very low probability that it would ever take place.
Thanks to Julian Gray, Curator and Geologist, Tellus Science Museum for taking the time to answer the questions I had about Earthquakes and their effects. If you have questions for Julian Gray I would be more than happy to pass them along.
