There are cost-effective indigenous methods, such as bamboo retrofitting, to counter the forthcoming earthquakes, which can be executed at very little cost
Far Western Province of western Nepal has been rocked by yet another earthquake as have several small ones in the past. This time, twin earthquakes jolted it on Tuesday, the 3rd of October, afternoon like tigers hunting in pairs. The first one with 5.3 magnitude hit at 2:40 pm. The second one, the larger one, quickly followed at 3:04 pm with 6.3 magnitude, according to the National Earthquake Monitoring and Research Centre. The second one was felt as far as the capital city Kathmandu.
Delhi, the capital city of India, was also shaken, forcing people to come out in terror.
Both these earthquakes had their epicentre in Bajhang district. The two earthquakes were followed by aftershocks, 11 of them in quick succession. These aftershocks virtually sent mini tremors in the mind and body of the people who have been staying in the open. Several buildings have collapsed, and many of them have developed cracks, some very wide. The damages can be seen mostly in Thalara, Jaya Prithvi and Chhabipathivara rural municipalities. One ladyhas been reported among the casualties, who was found buried in a landslide.
In fact, several landslides have occurred blocking the roads, which has caused inconvenience to the people who have already started to visit their native places to celebrate the forthcoming national festivals, Dashain and Tihar.
Earthquakes are marked by a movement in the ground, which is otherwise firm. Consequently, people in the past thought that the earth was carried by a multi-headed snake, the Shesh Nag, who gets tired due to the heavy load and moves it here and there, giving rise to an earthquake. It has now been proved that it is caused by tectonic movements of the Tibetan and Indian Plates. These plates are not stationery but move against each other with the Indian Plate entering the Tibetan one.
Over these plates are earth masses separated by a gap of fault. When these tectonic plates crack due to stress developed above the limits, the overlying blocks with faults existing between them rub against one another, giving rise to movement over which we live.
This phenomenon has been underway since timeimmemorial and will continue in the future. An earthquake is thus a fait accompli for Nepal, and it has to live and die with it.
The first earthquake was recorded to have occurred on December 24, 1223 when Abhaya Malla was ruling in Nepal. He escaped the first one but had to breathe his last in the 1255 earthquake, which had its epicentre in Gorkha. Yet an-other king, Ari Malla the Second, died in the 1347 earthquake a day later again with its epicentre in Gorkha.
Many earthquakes followed in the years 1260, 1408, 1505, 1680, 1767, 1834, 1869, 1916, 1934, 1966, 1980, 1988, 2011 and 2015. The analysis of these earthquakes shows that Nepal is hit by a high magnitude earthquake every 100 years and a moderate one every 50 years. The 2015 earthquake was of high magnitude, while the Bajhang earthquake is oneof moderate magnitude.
An earthquake is not new to Bajhang. It was struck by a quake in 1980 on the unfortunate evening of July 29, leading to the demise of 200 people and injury to 5,600. Some 13,258 houses were damaged, rendering 30,000 people homeless.
This earthquake, though of a similar magnitude to the one of 1980, led virtually to no casualties due to its oc-currence in the afternoon when people were outside, mostly working in the fields.
In western Nepal, no big magnitude earthquake has struck since 1505, the year when Ratna Malla was ruling in Nepal. Seismologists have opined that such a pressure has built up in the last 518 years that it can trigger an earthquake of 8.7 magnitude any time in the future. It will not only damage the Taj Mahal, which did not face the earthquake of 1505, being constructed in the year 1648, 11 years af-ter the Krishna Mandir in Patan, but also several buildings in the Indian capital, Delhi.
Damages can be seen in the houses of Bajhang, the most notable being the vertical cracks on the wall junction of one house in Thalara. One house in Jaya Prithvi has its roof on either side of the ridge gone down appearing like a sky light.
An earthquake hits the weak points, which are the double leafed wall, feebly jointed joists, rafters and ridges which dance during an earthquake, leading to the collapse of buildings as can be seen now in Bajhang.
There are cost-effective indigenous methods to counter the forthcoming earthquakes which can be executed at very little cost.
These are bamboo retrofitting and open jointed stone masonry, which have been constructed by the columnist.
The bamboo retrofitted houses in the year 2006 stood tall without being affected among the piles of the2015 earthquake in Kathmandu, Kaski, Sindhupalchok, Sindhuli and Dolakha. One in Sindhuli was used for a shelter after the earthquake.
Similarly, the open jointed stone masonry constructed below the ground can dampen the earthquake by 50 per cent. This experiment was carried out in a complex of Nepal Academy of Science and Technology. This technology does not address the less damaging primary and secondary waves but dampens the most damaging surface waves.
Unfortunately, the government has turned a deaf ear to such indigenous evidence-based technologies which can be executed around the country in very little time. Such technologies alone can save Nepal, which is likely to be hit by a large earthquake any time both in the east and west as in 2015.
Occasional earthquakes help to release the built energy.
They are thus like a blessing in disguise. But these 5.3 or 6.3 magnitude earthquakes are rather small in view of the impending 8.7 earthquake being equivalent to more than 3,200earthquakes of 5.3 or a hundred 6.3 magnitude earthquakes. It certainly indicates worse events likely to follow in the future.
Prof Pokharel is former Vice Chancellor, Nepal Academy of Science and Technology
A version of this article appears in the print on October 10, 2023, of The Himalayan Times
