Unlike aftershocks, rumours of another big earthquake are still hitting Nepal. This time, western part of Nepal has become hotter. Since earthquake of any part of the country can affect Kathmandu, the valley is again full of anxiety. I got request from some people to study on the possibility of earthquake in western Nepal. Some of my virtual friends also poured interest on my write ups. After 1 month research, I am here to publish my findings.
If you have read my previous articles on Nepal Earthquake, I know, you may think that I am going to say that there is no need to be stressed about earthquake in western Nepal. The topic of this article also refers it. If so, you are absolutely right. Wait, do not close it. I will give you strong logics. Let’s begin it from the button line.
Why was western Nepal taken as highly vulnerable to earthquake in near future?
Scientists have been warning for more than 30 years that western Nepal {west from Pokhara} may record huge earthquake which may have capacity to be the size of more than 8 Magnitude. This prediction has been made depending on the fact that the region has not experienced earthquake since 1505 AD.
What’s new the Scientists say about this risk?
Now some scientists say that the earthquake of 25 April had not relieved all stress. Now the remaining stress has shifted in the western part increasing the possibility of earthquake more seriously.
Is it true that the remaining stress has shifted to the western Nepal?
It is true that the energy released from the earthquake of 25 April did not come out completely. But I do not believe that the stress has gone to the western part. The reasons are:
a. This earthquake occurred in the eastern segment of the MFT fault {east from Gorkha}. That means the earthquake ruptured in the east which reached up to Dolakha district and stopped. But it had not gone towards western segment of the fault {from west of Pokhara to north of Delhi}. In this condition, is not it ridiculous to say that the stress has been stored in the western part of the country? It is similar to say that the river which flew from north to south made embankment in the northern part.
b. According to the worldwide concept observed by seismology, the earthquake or aftershock of one place can transform energy only up to little km distance from the epicentre. I think, if the stress had moved in the west that could have caused another earthquake within 3 days making 25 April a foreshock. If not, at least, that might have caused notably numerous small earthquakes in the west even today.
c. Had energy shifted to the west, the aftershocks would have stopped so far. But the aftershocks are still going on because the energy had not shifted to the west. Rather it is scattered below the crust and it is still releasing in form of aftershocks. This is the reason the aftershocks patterns are different in Nepal. This is my personal opinion.
d. All of us know that it is possible to estimate the stored energy through technology. And the scientists have claimed that the technology has proven that extra stress has been added in the western fault. But to confirm so, first they should have measured the energy stored in that place before the 25 April and reduced that energy from the energy stored today and then the remaining will be the added energy by this earthquake. Have they done so? I don’t think so. If not, it is only a business stunt.
So we can conclude that we cannot believe that the stress has gone to western part to increase the possibility of earthquake there.
Is it true that the energy has been locked in western Nepal for 500 years?
It is not sure for how long but it is true that the energy might have been locked in western Nepal for a long time. There are two proofs:
a. Practical proof: The statistics derived from the highly technological GPS stations have shown it.
b. Theoretical proof: The western Nepal is facing smaller earthquakes frequently before and after the 25 April event. This is my personal analysis.
The oddities earthquake may hit western region
We may say that this western region has not experienced big earthquake from 200-500 years. However it may not produce in near future. The possible reasons are:
a. Earthquake faults are not uniform everywhere. Some faults have smaller events whereas some faults have larger earthquakes.MFT {Main Frontal Thrust} has both large and small events. I think eastern segment of MFT has no smaller events. But it has large earthquake like 25 April. And the western segment of the fault has many smaller events which are postponing larger earthquake. So eastern parts are facing big earthquake and western parts have many small earthquakes that have prevented big ones from ages. Look at the following chart.
b. The second estimated reason is that the western part of the fault has several physical barriers {seismic barriers} along the fault. Some scientists say that these barriers are the cause earthquake did not move towards west. It stopped to the east in Dolakha because that is the edge of this fault. Study says the larger aftershocks are likely to strike at the edge of the fault. So May 12 may have happened there. I think these seismic barriers {segmented faults} are the causes western parts are not experiencing large hit. Instead it is facing smaller events. The energy is not stored hugely but it is divided in different segments. So it cannot be larger. If it is true it makes the energy shift concept more critical. If there is barrier, energy cannot shift.
c. The energy stored in the fault could have been steadily released through fault creeping. That means energy is being leaked slowly due to slide of the fault instead of cracking and producing an earthquake. If so it takes more than an estimated time to face a big earthquake. Or maybe, there would never be a big jolt. Because they are released through thousands of micro quakes. San Andreas Fault of California is one of its examples. The creeping segment of the San Andreas has not seen a large earthquake despite storage of huge energy qualified for a big earthquake. Is it happening in Nepal too? The research should be done. In my opinion, energy is definitely creeping in western fault of Nepal. But it is not being observed. Because they are not reaching surface like the huge hit of 25 April.
d. The bearing capacity of the rock of western Nepal may be strong. As energy may not have reached the threshold, the earthquake might have been postponed. If it is so there will be little doubt. But it is less likely. Because there are many earthquakes recorded in the seismograph every month.
e. It has been just 1 century we humans have started recording the earthquake. So we cannot say when earthquake occurred last time in the western segment of the MFT. What are the basis people claim this place is silent from 500 years? History is not enough to explain it. May be this place has seen earthquakes after 1505 AD too. And also, what is the strong base to believe that the energy which is not exploded since June 6, 1505 A.D. will be blasted in this decade?
f. This long term prediction of earthquake is based on the seismic gap theory. This theory is still controversial. Some foreign experts say that though tectonic move rate is similar, the method of energy release is different. So the earthquake does not necessarily repeats as happened before. Similarly, some Nepalese experts are saying that this theory has been designed especially in the area where continental plates and oceanic plate collide. But in the case of Nepal, the earthquake is caused due to collision of both continental plates, i.e., Eurasian plate and Indian plate. Moreover, the theory has yet to be studied in the Himalayan area like Nepal.
g. Every earthquake is different. Comparing one earthquake with another may work only as a reference. Earthquake taking place after a seismic gap in one place does not mean that same is going to happen in another place too.
What is the conclusion?
The 1505 earthquake has caused seismic barrier in western fault. So earthquake is not big there. But Eastern segment has no physical barrier. There is less small earthquake but a big event. Western Nepal has more small earthquakes and big one is unusual. 25 April released the strain at the eastern end. So this area can be taken as a safe place for some years. Moreover May 12 earthquake {aftershock} has ended the chance of big earthquake recently in the eastern part. But Western part should be observed continuously. If less {small} earthquakes occurred there, threat should be considered. Statistics say that eastern part time to time may face some bigger earthquakes {less than 7 M}. But every century it may cause a huge earthquake of around 8 M. But the time interval as well as the magnitude is also decreasing. In previous time it was about 8.2 with 100 years gap. It decreased in this year. Now may be after 50 years with less than 7.8 M. If it is so, this segment is also never going to face big earthquake greater than 7.8 M.
Final Words
Earthquake is still a mysterious science. We humans actually do not know the real cause of the earthquake. However tectonic theory is widely used. In my opinion, Tectonic Theory of Earthquake is similar to Big Bang of the Universe. Unlike big bang, tectonic theory is also partially controversial. Actual cause of the earthquake is still unknown. So the best thing to do is to follow the preventive measures of earthquake on time. Special attention should be given by the government. As Nepal is one of the most sensitive earthquake hazardous zones of the world, the government should give more priority for the research of earthquake..
Disclaimer: This article is the personal opinion of the author. It has been shared only for educational purpose. The author and National Discovery Channel are not liable to any personal or institutional decision made on the basis of it.
Discovered by Don Prince
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