Dynamic Earth: Earthquakes, Tsunamis, Supermoons, and Japan

Tsunami Wave
from National Geographic

Earthquakes occur all the time; look at the USGS list of earthquakes in the past 8-30 days. There are a few hundred entries, most around a magnitude of 4 or 5. The plates that make up the Earth's crust move about constantly, so these minor tremors are quite common. A 4 on the Richter scale is strong enough to be felt, but not strong enough to cause much concern or damage. There are a couple thousand of these a year. Anything less than a 4 is a microquake; these are too weak to be felt, and are only recorded on local seismometers. Anything more than a 7 or 8 is a "great" earthquake. These are far less common; usually, there are only one or two great earthquakes per year. These earthquakes are the ones that cause trouble when they hit populated areas.

The earthquake that hit Japan last Friday was undeniably a great earthquake. It ranks as a 9.0 on the Richter scale, making it the 4th largest earthquake to occur in the past century. It caused a lot of damage, and in some places moved the crust by as much at 8 inches. Like the strong Chilean earthquake a year ago, it also shifted the Earth's axis slightly, shortening the day by about 2 microseconds (source). It also triggered a massive tsunami that hit Japan, Hawaii, and the US west coast, causing even more damage. Currently, Japan is still on alert as the Fukushima nuclear power plant threatens meltdown from damaged caused by the quake and tsunami. Evelyn, one of the Skepchicks, has been following this crisis with her father, a nuclear engineer, and has some great information up at her Georneys blog. It was truly a devastating quake, and needs to be seen to be truly understood.




This is a major natural disaster, and Japan need support and assistance from the rest of the world. What they do not need are a lot of pseudoscience explaining why the earthquake occurred or how recovery efforts should be run. One of the first pieces of nonsense was the supermoon idea. On March 19th, the moon will be closer to the Earth than at any other point during the year, and will also be full. Some astrologists claimed that this would increase the tidal forces to the point where the continental plates moved. This is simply wrong. First off, no matter where the Moon is in its procession and cycle, the tidal forces aren't strong enough to cause anything more than a microearthquake, if that. Second, the quake did not occur on the supermoon day; it occurred a week before, where the Moon is not at the minimum distance from the Earth, and when it has the weakest tidal forces in the monthly cycle. There is simply no way that the Moon had any causal effect on last Friday's earthquake.

The second, somewhat disturbing, piece of pseudoscience is the homeopathic groups distributing their medicines for nuclear radiation. Homeopathy, for those that don't know, is the concept of diluting a substance repeatedly, supposedly increasing the strength of the remedy each time it is diluted. (Mad Art Lab did an excellent job of illustrating the idea.) How this works for radiation, I don't know. These groups are trying to help, but are doing so with nonsense, and will likely cause more harm than good.

If you want to help the recovery efforts, first educate yourself; there is a lot of information available, both good and bad. If someone makes a claim about a natural disaster, check science sources, such as the USGS Earthquake page, to find out the facts, and sites like ScienceDaily and LiveScience to find out what the experts are saying, without as much of a media spin. Searching skeptical sites is also a way to sort the wheat from the chaff. Then, look into how you can help. There are some other groups doing real work. Doctors Without Borders and the Red Cross both do very good work, and are engaged in Japan right now. These groups provide shelter, real medicine, food, and materials to those affected by the disaster.