Myanmar earthquakes and the ‘Fault’ behind

Myanmar and neighbouring Thailand were rocked by powerful back-to-back earthquakes on Friday with impact also felt in India’s northeastern states, including Manipur and Meghalaya.

The first earthquake of 7.2 magnitude struck around 11.50 am, followed by a second one of 7 magnitude at 12.02 pm and yet another measuring 5 around 12.58 pm, according to the India Meteorological Department (IMD).

Widespread damage was reported in Thailand’s Bangkok where a state of emergency has been declared. An earthquake of 4 magnitude was also reported in Meghalaya at 1 pm, according to the National Centre for Seismology, thereby highlighting the region’s vulnerability to earthquakes

Seismically active zone

Myanmar is one of the most seismically active regions in the world with the Sagaing Fault being one of the main major reasons contributing to the region’s vulnerability to earthquakes.

The Sagaing Fault is a “mainly continental right-lateral transform fault between the Indian plate and Sunda plate”. With a total length of around 1,200 km, the fault has generated several earthquakes of high magnitudes in the past.

The “continental right-lateral transform fault between the Indian plate and Sunda plate links the divergent boundary in the Andaman Sea with the zone of active continental collision along the Himalayan front, passing through the populated cities of Mandalay, Yamethin, Pyinmana, the capital Naypyidaw, Toungoo and Pegu before dropping off into the Gulf of Martaban,” according to geologists.

The fault has been associated with some of the most damaging earthquakes. Basically, a geological fault is a “planar or gently curved fracture in the rocks of Earth’s crust, where compressional or tensional forces cause relative displacement of rocks on the opposite sides of the fracture.” It may be vertical, horizontal, or inclined at an angle.

The Sagaing Fault has two landmasses moving sideways past each other with the shift building stress. When this stress is released, earthquakes result.

India too is highly seismic

The fact is, there is no seismically safe zone in India. The entire subcontinent is sitting on the highly seismic Indian plate with some major fault lines. The Indian plate is one of the 12 major plates locked together to the surface of the earth like a jigsaw puzzle. Its boundary is active, gradually moving, pushing against the Eurasian plate by 4 to 5 cm every year. Active thrust faults exist all across foothills in North India, the North-East and into northern Pakistan.

Major faults exist from North-West to East and the North-East in India

According to scientists “Indian tectonic plate is moving about 5 cm every year, leading to accumulation of stress along the Himalayas and increasing the possibility of major seismic events in the coming days”.

There have been several minor/moderate quakes in the region. In April 2015, two back-to-back earthquakes measuring 7.8 and 7.3 on the Richter followed by several high-intensity ones, resulted in damage worth $10 billion and death of 9200 persons in Nepal, according to available data.

India's four seismic zones — Zone-II to Zone V

Almost 59 per cent of India is prone to earthquakes of different magnitudes—11 per cent in Zone V, 18 per cent in Zone IV and 30 per cent in Zone III.

Very high-risk Zone V with the highest seismic intensity comprises the north-eastern areas, parts of J&K, Himachal Pradesh, Uttaranchal, Rann of Kutch and north Bihar.

High risk Zone-IV covers the remaining parts of J&K and Himachal,  Delhi, Sikkim, northern parts of UP, Bihar and West Bengal, parts of Gujarat, some parts of Maharashtra near the west coast and Rajasthan.

Moderate risk Zone-III includes Kerala, Goa, Lakshadweep islands, the remaining parts of Uttar Pradesh, Gujarat and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Orissa, Andhra Pradesh, Tamil Nadu and Karnataka. The rest of the country is Zone-II.

Can earthquakes be predicted?

According to the United States Geological Survey, the scientific agency of the United States government, “neither the USGS nor any other scientists have ever predicted a major earthquake”

“We do not know how, and we do not expect to know how any time in the foreseeable future. USGS scientists can only calculate the probability that a significant earthquake will occur (shown on our hazard mapping in a specific area within a certain number of years,” the USGS website states.

An earthquake prediction must define three elements — the date and time, location, and magnitude.

So far as predictions by “non- scientists” are concerned, the USGS states that “yes, some people say they can predict earthquakes, but they are not based on scientific evidence, and earthquakes are part of a scientific process.”

Should one be worried

Strange as it may sound, earthquakes do not kill, it is the structurally unsound buildings and structures that do. Experts say earthquakes are a hazard that need not get converted into a disaster if buildings are safe, everyone follows the law and there is a proper disaster management plan in place.

Thousands of earthquakes happen every day, meaning they are part of a natural process, the action going inside the Earth. In fact, most are too minor to even feel.

To understand the process, sudden shaking is caused by the passage of seismic waves through Earth’s rocks. Seismic waves are produced after energy in Earth’s crust is suddenly released when rocks straining against one another suddenly fracture/ slip.

Across the world, major fault lines are located on fringes of major and minor tectonic plates that make the Earth's surface. And these tectonic plates are in constant motion, floating on the asthenosphere, the mechanically weak and ductile region of the upper mantle, driven by various forces underneath.