On Thursday (24/3) night, an earthquake of 6.8 magnitude hit Burma, near the Thailand border - 235 kilometers north-east of Chiang Mai, which is the second most populous city in Thailand as well as a popular tourist destination, to be exact. The last report announced that at least 75 people were killed in the disaster and at least 100 are injured. The earthquake could be felt in Bangkok, Hanoi and parts of China.
And just almost two weeks ago, a grand quake of 9.0 magnitude hit Japan, triggering the massive waves of tsunami and causing nuclears to explode. The earthquake and tsunami have been dangerous themselves, and now the radioactive from the nuclears are contaminating water and food supplies, causing even more danger to the Japanese. This also means they will be shorter on refreshements.
A lot of earthquakes have been occuring lately - mostly tectonics - and they often have other disasters following, natural or otherwise. And for this reason, even though I am not an expert in geography - never have been - I am going to discuss about the Richter Magnitude Scale, which is, as far as I know, the most frequently used scale used to measure earthquakes.
The Richter scale was developed by Charles Richter (hence the name) in 1935. According to Wikipedia, the original formula of the Richter scale is
in which ML stands for Local Magnitude, otherwise known as the Richter magnitude.
The information below describes the typical effects of earthquakes of various magnitudes near the epicenter. The values, though, are typical only and should be taken with extreme caution, since intensity and thus ground effects depend not only on the magnitude, but also on the distance to the epicenter, the depth of the earthquake's focus beneath the epicenter, and geological conditions (certain terrains can amplify seismic signals). In other words, the effects and intensity of the effect may vary according to distance to the epicenter, the earthquake's focus beneath the epicenter and the location of the tremor. The nearer the quake's focus to the surface, the stronger the effects will be.
Earthquakes of magnitudes less than 2.0 are described as micro earthquakes and cannot be felt by humans. About 8,000 of these are recorded everyday. These earthquakes are not dangerous, considering that about 8,000 of them occur daily and we hardly feel anything from them. Earthquakes of magnitudes 2.0 - 3.9 are described as minor earthquakes - tremors of 2.0-2.9 magnitudes are generally not felt, but recorded, and about 1,000 of these occur daily, while the ones of 3.0-3.9 magnitudes are often felt, but they rarely cause damage. About 49,000 of these happen per annum.
Earthquakes that are considered light are of 4.0-4.9 magnitudes. Light earthquakes cause noticeable shaking of indoor items and rattling noises, although they are unlikely to cause severe damage. About 6,200 of these earthquakes are recorded per year. Moderate earthquakes are of 5.0-5.9 magnitudes. They can cause major damage to poorly constructed buildings over small regions, and at most slight damage to well-designed buildings. 800 of them happen per year.
Earthquakes of magnitudes 6.0-6.9 are considered strong and around 120 of them occur each year. They can be destructive in areas up to 160 kilometres across the populated area. Earthquakes of magnitudes 7.0-7.9 are considered major and cause serious damage over larger area. About 18 of these are recorded per annum.
Now we're getting to the most severe ones. Great earthquakes are those of 8.0-9.9 magnitudes. They can cause damages for hundreds of kilometres across, or thousands for those with 9.0-9.9 magnitudes. Earthquakes of magnitudes 8.0-8.9 happen about 1 per year and the ones of magnitudes 9.0-9.9 are recorded once in 20 years. The final one, which is only theoritical, is of magnitudes 10.0+ and is considered massive. It has never happened before.
Following this post might or might not be little tips on what to do in earthquakes that the author has obtained from various schoolbooks, posters, and television. Stay tune, and Chro says goodbye because she has to go to dinner now. Adieu and have an adventurous day!
~Chro
| Richter magnitudes | Description | Earthquake effects | Frequency of occurrence |
|---|
| Less than 2.0 | Micro | Micro earthquakes, not felt.[6] | About 8,000 per day |
| 2.0–2.9 | Minor | Generally not felt, but recorded. | About 1,000 per day |
| 3.0–3.9 | Often felt, but rarely causes damage. | 49,000 per year (est.) |
| 4.0–4.9 | Light | Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. | 6,200 per year (est.) |
| 5.0–5.9 | Moderate | Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings. | 800 per year |
| 6.0–6.9 | Strong | Can be destructive in areas up to about 160 kilometres (100 mi) across in populated areas. | 120 per year |
| 7.0–7.9 | Major | Can cause serious damage over larger areas. | 18 per year |
| 8.0–8.9 | Great | Can cause serious damage in areas several hundred kilometres across. | 1 per year |
| 9.0–9.9 | Devastating in areas several thousand kilometres across. | 1 per 20 years |
| 10.0+ | Massive | Never recorded, widespread devastation across very large areas; see below for equivalent seismic energy yield. | Extremely rare (Unknown) |
| Richter magnitudes | Description | Earthquake effects | Frequency of occurrence |
|---|
| Less than 2.0 | Micro | Micro earthquakes, not felt.[6] | About 8,000 per day |
| 2.0–2.9 | Minor | Generally not felt, but recorded. | About 1,000 per day |
| 3.0–3.9 | Often felt, but rarely causes damage. | 49,000 per year (est.) |
| 4.0–4.9 | Light | Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. | 6,200 per year (est.) |
| 5.0–5.9 | Moderate | Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings. | 800 per year |
| 6.0–6.9 | Strong | Can be destructive in areas up to about 160 kilometres (100 mi) across in populated areas. | 120 per year |
| 7.0–7.9 | Major | Can cause serious damage over larger areas. | 18 per year |
| 8.0–8.9 | Great | Can cause serious damage in areas several hundred kilometres across. | 1 per year |
| 9.0–9.9 | Devastating in areas several thousand kilometres across. | 1 per 20 years |
| 10.0+ | Massive | Never recorded, widespread devastation across very large areas; see below for equivalent seismic energy yield. | Extremely rare (Unknown) |
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