Sri Lanka has experienced a series of minor tremors in the first four months of the year, causing concern among its citizens. Nine earthquakes were recorded in various parts of the country, with the most recent occurring just a few days ago. While none of the tremors has caused significant damage or injuries, they have raised questions about the frequent and unexplained occurrence of earthquakes. Many wonder if these tremors are a sign of more serious seismic activity to come.
The Sunday Observer reached out to the Director General, M.M.J.P Ajith Prema from the Geological Survey and Mines Bureau (GSMB) for some answers. “The possibility of more minor tremors taking place cannot be ruled out,” he said. “However the likelihood of earthquakes recording much higher magnitudes is unlikely.”
In comparison to the previous years, the geologist said there’s been an uptake in the number of quakes. Some 16 such tremors were recorded in 2020, 18 in 2021, 5 in 2022, and 9 within the first four months of this year.”
“Sri Lanka lies in the boundary between the two tectonic plates, the Indian Plate and the Australian Plate. Quakes, which are a common occurrence as we’ve seen in the Himalayan Mountain Range, that happen on either plate can have an impact on countries,” he said.
Geologically, the Northern and Eastern parts of Sri Lanka are located on the Indian Plate while the southern and Western parts are on the Australian Plate. This tectonic boundary is known as the Indo-Australian plate and is a place that is a highly active region where earthquakes and volcanic activity are not uncommon. “However, Sri Lanka itself is not situation on any major fault lines and generally experience low to moderate seismic activity,” he added.
Another point of consideration by geologists has been the Northern end of the plate, which is the Himalayan range is geologically crashing against the Asian plate causing stress. The stress of this level, geologists like him say, could be transmitted across the Indian mainland and Sri Lanka could experience some of these effects.
Long-suspected geological phenomenon
Recent geological studies, most notably by James Cochran of the Lamont-Doherty Earth Observatory, however, found evidence for a long-suspected geological phenomenon. The Indo-Australian plate according to him is splitting. Cochran shows evidence to illustrate that Australia and India are going separate ways forming a new defuse, plate boundary. Prema, however, cited such formation is taking place at a snail’s pace and could take a million years before it fully breaks away.
So far nine earthquakes have occurred in Buttala Beruwela, Kirinda, Gomarankadawala, and Hambanthota areas. The biggest of which so far was a quake that measured 4.4 on the Richter scale off the coast of Hambantota. The earthquake occurred at around 12.45 am on Monday (24) and was around 25.8 kilometres Southeast of Hambanthota with a depth of 3 kilometres.
“Given the frequent occurrence of these tremors, we are working in close coordination with the Disaster Management Centre as well as the Meteorology Department. We also have an Earthquake monitoring centre that functions 24/7 with a hotline for citizens to call and report any seismic activity,” said the geologist.
More seismometers needed
Prema said that Sri Lanka could no longer rely on the four seismometres in our country and hence discussions are under way to set up the 5th in the Gampaha district. Presently, the four are in Hakmana, Mahakanadarava, Peradeniya, and Pallekele.
When asked if the likelihood or zones of future quakes can be predicated, he added that attempting to predict the occurrence or non-occurrence would be more speculative than predictive science. He added that prediction of the time, date, or zone of future quakes or tsunamis is still one of the frontiers of scientific research and it will be several decades before such accurate prediction materialises. Rather, he said, it is the ‘probability of occurrence’ that is based on geological and geophysical data, with a margin of error.
“Another reason why we are seeing heightened interest is also the advances in communication and digitalisation,” he said. “Today, more than ever, people have access to information in real-time and can read up or share the news, so even the smaller detections are publicised.”
He added that Sri Lanka plans to create Earthquake zonation maps by collaborating with countries such as India so data could be shared and used to build such databases.