How do we measure the strength of earthquakes? Detailed answer

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How do we measure the strength of earthquakes? Detailed answer

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How do we measure the strength of earthquakes?

On the MMS scale (otherwise - the magnitude scale of the seismic moment, or the Kanamori scale). The MMS scale was developed in 1979 by seismologists Hiro Kanamori and Tom Hanks (no connection) at Caltech. Scientists considered the generally accepted Richter scale insufficient, since it only measures the strength of seismic waves, which does not fully reflect the consequences of an earthquake. Serious earthquakes that have the same score on the Richter scale can cause destruction of completely different scales.

The Richter scale measures seismic waves (or vibrations) felt at a distance of 600 km from the source of an earthquake. It was proposed in 1935 by Charles Richter, who, like Kanamori and Hanks, worked as a seismologist at the California Institute of Technology. Richter developed his scale together with another scientist, Benno Guttenberg, who was the first to accurately measure the radius of the Earth's core. Ruttenberg died of the flu in 1960, before he could measure the Great Chile earthquake (the strongest ever recorded and four months later).

Unlike the Richter scale, the MMS scale is an expression of the energy released during an earthquake. The seismic moment here is calculated by multiplying the displacement of the two parts of the fault by the total area of the affected zone. The goal is to give values that are more understandable than their equivalents on the Richter scale.

Both of these scales are logarithmic: an increase of two points means 1000 times more energy. So, a hand grenade explosion is 0,5 on the Richter scale, and an atomic bomb in Nagasaki is 5,0. The MMS scale is used only for large earthquakes - above 3,5 on the Richter scale.

According to the US Geological Survey, the largest of all officially recorded earthquakes in North America were the little-known earthquakes in the Mississippi River Valley in 1811 - 1812 - based on the area affected (600 thousand square kilometers) and the area on which tremors were felt (5 million sq. km). As a result, new lakes were formed, the river bed was completely changed. The area of sensitive shaking was ten times greater than that which took place in San Francisco in 1906. Church bells rang on their own all the way to Massachusetts.

It is impossible to predict when the next earthquake will occur. One expert argued that the most reliable way was to count the number of advertisements for missing dogs and cats in the local newspaper.

In Britain, up to 300 earthquakes occur every year, but they are all so small that only one in ten is noticed by the population.

Author: John Lloyd, John Mitchinson

Random interesting fact from the Great Encyclopedia:

Where did bananas originate?

Bananas are the oldest fruits known in history. The most ancient people knew bananas and admired them. It is believed that bananas originally grew in South Asia, and over the centuries spread to the west and east. The Muslims called the banana palm the tree of paradise, while the Hindus deified bananas.

At the beginning of the XNUMXth century, the priest Thomas de Berlanga brought banana roots to the New World. He hoped to win friendship with the Indians with this sweet, golden fruit and thus convert them to his faith. From these little roots grew a whole banana plantation of thousands of acres, which still exists in the tropical region of America!

The Indians found a variety of uses for bananas. They fry them while the bananas are green, eat them instead of bread. They boil them like vegetables, stew them, dry them like berries, and even make a strong alcoholic drink out of them! Although we say that bananas grow on a tree, it is actually not a tree, but a bush. It is probably the largest shrub in existence without a tree trunk. The stem, which reaches 3,5 to 9 meters and looks like a real tree trunk, is actually a mass of tough leaves.

The most developed banana varieties have lost the ability to produce seeds, which is much more convenient for eating. At the top of the plant is a huge tuft of hanging leaves, bright green in color. It is they that resemble a palm tree, make a banana look like a palm tree. One large flower bud grows in the middle of the trunk. And at the right time, it is on it that fruits appear. Since bananas grow in heavy bunches, the stem of the bush bends down.

It turns out that bananas grow upside down. Each bush grows one bunch of bananas, but its weight often reaches 45 kilograms or more! Bananas are always harvested while they are green, even when they are not going to be sent somewhere far away for sale. The reason is that if they are allowed to ripen on the tree, they burst and spoil before they are plucked. Bananas are transported on special ships built to transport bananas. They must be ventilated with a stream of cold air so that the fruits do not ripen during transport.

Test your knowledge! Did you know...

▪ How is mass distributed in the solar system?

▪ Why does a scorpion sting?

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Gut bacteria can affect mood 19.02.2019

A study by Belgian scientists has shown that many intestinal bacteria can produce substances that affect nerve cell function and possibly mood.

Previously, several studies in mice have shown that gut microbes can influence animal behavior, and small human studies have shown that microbial composition in the gut changes with depression. To test the strength of the link between the human microbiome and mental health, Jeroen Raes, a microbiologist at KU Leuven (Belgium), and his colleagues studied a large group of people to assess a "normal" microbiome.

A total of 1054 Belgians participated in the study. Some of them - 173 people - were diagnosed with depression or scored poorly on quality of life tests. The team compared the state of the gut flora of participants with depression and the rest of the subjects. It turned out that in people with depression, the level of microbes such as Coprococcus and Dialister remained low in people's microbiomes. It didn't matter if people were taking antidepressants or not. Conversely, participants who claimed to have a high psychological quality of life had high levels of these microbes.

The team then looked at the medical test results of another group, which included 1064 Dutch people. The researchers found that the same two types of bacteria were absent from the microbiomes of those people who were depressed, as well as seven participants suffering from severe clinical depression. Scientists admit that the data do not currently support a causal relationship. Perhaps the effect even works the other way around: it’s not microbes that affect our mood, but our mental health affects the state of the microbiome.

However, in subsequent experiments, the researchers found evidence that microbes can communicate with our nervous system by producing neurotransmitters that are responsible for transmitting electrochemical impulses to nerve cells. Scientists have found, for example, that Coprococcus appears to have a pathway associated with dopamine, a key brain signal that is responsible for feelings of satisfaction.

The discovery could lead to new probiotic treatments for depression that could help increase levels of essential microbes in the human gut. However, many more studies need to be done to confirm that microbial compounds produced in the gut can affect our brain.

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