I am surprised we are facing aftershocks for more than a month, but we are still confused with miner things about aftershocks. This aftershock is felt to be big only because epicentre was in the local area. If we make a call to the people of other districts and asked them about it, then most of people will definitely respond that they did not even feel it. Because they are far from the epicentre. Talking about the sound, our ear is not so much capable to hear the sound of wave emerged below the crust. I mean we can’t hear the sound of earthquake wave. The sound which we hear during earthquake or aftershock is the sound of the buildings and their properties on the earth due to the earthquake tremors. And even 4 M earthquake may give experience of sound near the epicentre because it is more powerful than in the other places far from the epicentre. So earthquake along with sound is not the siren of the next big earthquake.
Similarly having epicentre in Kathmandu does not necessarily mean that the city is vulnerable to a big quake. Aftershocks occur in and around the rupture zone. As being in the rupture zone it is obvious that places like Kathmandu, Dolakha, Nuwakot, Rasuwa, Sindhupalchowk, etc will experience aftershocks. It does not mean they will get another big shock. Aftershocks do not move as we think. Aftershocks happen when the stored energy reaches threshold.
After this incidence, I decided to list out and explain the rumours I heard during my offline visit in different places. I have also included the questions readers asked me online. They go like this:
1. USGS statistic predicts earthquake
Many people mistakenly believe that USGS predicts earthquake. Most of the time USGS analysis report is misinterpreted. It happened in its greatest level in Nepal. When USGS showed 0.03% chance for big tremor and 99.07% confidence not to experience large tremor, it was misinterpreted. And the common people also followed 0.03% rather than 99.07%.
The analysis of USGS is ‘forecasting’ based on statistic. Statistic is not accurate. Anything proven statistically or mathematically won’t be accurate. We can prove a cup of tea to be a glass of wine mathematically. That does not mean that you have taken wine instead of tea. And also, there is difference between forecasting and prediction. Forecasting is long term estimation whereas prediction is accurate with time, space and level. USGS itself says that it focuses on long term forecasting of earthquake rather than the short term earthquake prediction.
2. Some animals can give signal of the earthquake
Some people have reported that animals can predict the earthquake. According to them, these animals show amazing behaviours before earthquake. There are some instances in China and Japan. So, most of the Chinese and Japanese scientists believe on this theory.
So far there is no repeated record to prove animals can give signal of the earthquake so that caution can be applied in the future. Such types of animals’ behaviours are confusing. But it is true that they can hear P wave sooner than humans. As only p wave can move through the fluids below the crust, it arrives first. So animals feel it and show amazing behaviour with the fear of earthquake. Later humans feel the earthquake.
3. Ground can open during earthquake
Many people fear ground can open and swallow them during earthquake. Can it be?
If you fall into the hole made by earthquake, the chances are high that you will jump out of it. If ground opens to swallow, there won’t be possibility of earthquake.
4. Earthquake can not strike at night
People often remain scared at night during aftershocks. But some people say that earthquake does not take place between 12 to 4 am. People also believe that earthquake can happen especially in the morning time.
Yes, there are less earthquake events in the time between 12 to 4 am and also earthquake is recorded more in the morning time. But there are some instances where earthquake has occurred during night hours. Earthquake has also taken place in the day time. Nowadays, you may also notice aftershocks happening at night in Nepal. If you can prove that earthquake is more likely to happen in morning and it is rare at night, then you can be an established scientist.
5. There is special kind of weather before earthquake
Some people say earthquake can occur in special type of weather. They also believe that earthquake does not occur in the rain. There are also many theories which claim special type of weather before earthquake.
Earthquake has struck in any type of weather. Statistics says that there is no special type of weather for earthquake. It can happen in any weather situation. So far no one has proven there is special type of weather before earthquake. Nepal has experienced some aftershocks with rain as well as powerful wind.
6. Snakes come out of the ground before earthquake
Some people said that snakes are appearing in some places before the earthquake. So they believe that this is the sign that another big quake is coming. Ultimately they spread fear of earthquake depending on the appearance of snakes.
The actual reason is that snakes come out of the ground when aftershock takes place. They are coming out side not because earthquake is coming, but because earthquake has taken place.
7. Earthquake can return
Most of the people believe earthquake returns again. So they fear till they are escaped in another big quake. But the reality is different.
I think this concept has been started after the earthquake of 1934 in Nepal. I guess the earthquake of 1934 {1990 BS} had experienced stronger aftershock. So people believed earthquake returns. But that type of earthquake after long time interval is strong aftershock. As there is possibility of strong aftershock depending on the size of the earthquake, people have misconception that earthquake has returned.
8. The rose ground should settle to the same position as before by another earthquake
There is belief that when the ground rose due to earthquake there will be another earthquake to settle them. They also think the rose part must be settled.
Do we need another earthquake to settle mountains which rose due to earthquake years ago? Obviously not. And the stressed part below the crust settles, not the surface.
9. Independent earthquake in another zone during aftershocks is the symbol of another big quake
Many people believe if there is another independent earthquake very far from the rupture zone during aftershocks sequence, this is sign of another earthquake in another place.
Earthquake takes place several times in a year. The new independent earthquake is also usual, natural and normal.
10. Earthquake less than 4 M is not recorded
Some people say earthquake below 4 magnitude is not recorded. Because they don’t find it through media and in official websites.
Earthquake less than 4 magnitude is also recorded but they are not flashed in some countries like Nepal as they are not harmful and they can’t be felt too.
11. If all animals are killed, there won’t be earthquake
There is belief that Einstein said in his theory if all animals are killed, there will never be earthquake. Is that true?
This is based on pain wave theory which is not created by Einstein. People think that this is created by Einstein. Because the name of this wave is EPW, i.e., Einstein’s Pain Wave. The theory says that when animals are killed, their pain goes inside the crust as wave and they cause stress in the rock and eventually earthquake. But it is not proven.
12. Animal can speak before earthquake
Some people have reported that they found animals speaking about earthquake. Villagers in Nuwakot of Nepal have said that some animals spoke and said that big earthquake is coming.
Yes, it is true animals speak before earthquake. They speak not only before earthquake. All of us know animals always speak but we don’t understand what they speak.
13. Planets alignment can affect earthquake
Sometimes there is belief that the alignment of planet can cause earthquake. This concept had serious effect in California.
There is no evidence to prove the effect of planets alignment on earthquake. May be, it affect earthquake, but that can’t be issued reliably to predict earthquake.
14. Aftershocks are the symbols of another earthquake
Some believe that there is chance of big earthquake till aftershocks disappear. So they are anxious till aftershocks are stopped.
Aftershocks are normal after a big quake more than 7 M. It may take days, months and sometimes years to stop. They continue till the stresses created by main earthquake on the rocks are settled. They don’t mean chance of another earthquake.
15. Only 40% energy is released by mainshock
There is often belief after a big earthquake that a huge percentage of energy is still remained which can trigger another bigger earthquake. Some people estimated it during Nepal Earthquake 2015. They believed that 60% energy is stilled stored that may cause bigger quake.
Bigger blast is in the beginning. Smaller blast happens with aftershocks. If there is 60% energy left, that may cause foreshock {see also}event. But it did not happen in Nepal. In the other hand, if it is confirmed that still 60% energy is left that can trigger earthquake very soon, government could evacuate the cities and scientists could create manual earthquake by inserting fluids under the ground to increase stresses in the crust so that there is blast before people enter their houses.
16. Earthquake is caused due to fish staying under the earth
This is old saying that earthquake is caused because the earth is on the fish. When fish moves, the earth starts shaking.
We have complete glance of earth from the space. There is no fish below the earth. A scientist has asked a question in the past, ‘If earth is on the fish, where is the fish on?’
17. Humans are the cause of earthquake
Many people believe humans are responsible for earthquake. They specially link it with global warming and environmental degradation.
Humans are not the cause of earthquake. Earthquake happens naturally below the crust which is far from the human activities. However some human activities like extreme mining, use of maximum fluids, etc can cause earthquake.
18. High magnitude earthquakes are always dangerous
People often fear with high magnitude earthquake but they may not prepare for smaller quakes.
19. Earthquake can be predicted by astrology
Astrology becomes hot after big earthquake. People estimate time and magnitude of another earthquake using the knowledge of astrology. Common people easily believe if anyone claims that there will be another big earthquake. And they get more scared.
Is there any incidence where anyone really came ahead of the earthquake day using astrology and saved the people? If there is any astrologer who can predict earthquake with exact time, location and magnitude, he/she can be the renowned scientist of the world.
20. Horizontal quakes are more dangerous
Considering the sideways movement of houses during earthquake, some people believe that horizontal quake is more dangerous than vertical quake.
Vertical quakes are more dangerous than horizontal quakes. This is widely accepted fact.
21. Earthquake waves move equally in every direction
There is established belief that the wave of earthquake moves equally in all direction. There is popular example of pebbles throwing in the pond where waves move equally in all direction making circle.
The waves of earthquake may change direction according to the weakness of the rock. It happened during the earthquake of Nepal.
22. Earthquake can convert a place into a lake
Some believe earthquake can convert a place into lake. It is said during the earthquake in Nepal.
Is there any incidence of this kind in the history of the earthquake?
23. Earthquake can sink whole city
Many believe earthquake can sink city. Last month, California was said to sink in sea with earthquake which was proven completely wrong.
If there is any incidence like that, please let me know too.
24. Some people have Sense of earthquake
Some believe some can know the earthquake going to strike by using a special kind of sense.
USGS says it is unknown. There is no such kind of evidence where anyone has predicted earthquake by using any sort of sense.
25. Tectonic collision is the cause of the earthquake
There is wide spread consensus that earthquake takes place due to the slip or collision of tectonic plates.
It is based on tectonic theory which is one of the theories developed on how earthquake causes. But what is the real cause of earthquake is still unknown. We can compare this theory with the big bang theory of the universe. Big bang theory is one of theories developed to explain how universe began. But what is the secret behind the beginning of the universe is still unknown.
When a big earthquake strikes anywhere, possibilities are more that rumours begin. In the other hand there will be more chances that even scientific analysis will be misinterpreted and chaos and confusion appear uncontrollably. The best thing must do by the government and a conscious citizen is making people aware on time before the earthquake and rumours.
Sometimes new situation creates confusion. For instance, when the magnitude of the aftershocks suddenly increases and people suspect another earthquake. But the reality is that number of aftershocks decreases exponentially but the magnitude is still uncertain. If there are low magnitude aftershocks, the numbers are more {see this}. If there are high magnitude aftershocks, the numbers are less. Chances of higher magnitude aftershocks will be low with time. And then the aftershocks stop.
Now this is the time to exchange our knowledge with each other. Have you heard any kind of rumours or confusion? If you have heard any rumours and confusions, please mention them in the comment section below. You can also give scientific reasons for them. I will definitely try my best to give scientific reasoning from my side.
Discovered by Don Prince
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