Unusual ground sounds in Hedunuwewa linked to underground water pressure: Geological Expert

• Urges coordinated investigation for clarity  

By Kelum Bandara   

Asserting that the most potential reason for the unusual sound heard by people as originating from the ground in the Hedunuwewa areas in the Nuwara Eliya District could be due to pressure in the underground water table, a geological expert said the exact reason could be ascertained only after a proper geological investigation or research under available methods.  

 Professor of Earth Resources Engineering University of Moratuwa and President of Institute of Geology Sri Lanka Prof. Ranjith Premasiri told Daily Mirror that the proper coordination among the institutions related to disaster management- National Building Research Organization, Disaster Management Centre, Geological and Mines Survey Bureau jointly with universities - is vital in responding to an emergency like this rather than making ad hoc conclusions.   

Prof. Premasiri who listed out potential reasons for such noise from the ground said it is triggered by wave propagation or seismic waves resulting from the fracture of underground rocks or any other cause that releases some energy in the ground. Also, he said it could be triggered by the pressure generated in groundwater and released through geologically weak zones, creating instability in the ground.   

“The most potential cause in this instance can be pressure in the underground water as this is happening in intense rainy seasons and people have observed some unusual phenomena in groundwater tables such as sudden lowering of the groundwater table. 
We have to do a geological study to establish it. Such pressure can increase due to underground fractures and cavities in geologically weak zones in the earth,” he said.   
Referring to various methods available for such a study, he said a modern geophysical survey such as a seismic survey, as mostly done in petroleum exploration, could be used as a microseismic survey.   

Gravity method, electromagnetic surveys such as GPR, and Electrical resistivity method are other options to be tried.   

After proper geological study as he proposed, the most potential cause for the phenomena could be identified. Then appropriate mitigation options can be propped.   
Asked about possible responses in the event of such an emergency, he said such a sound from the earth does not mean a disaster will always follow.   

However, he said soft engineering methods such as relocation of people, monitoring and establishment of early warning systems to improve the areas and make the community more resilient and hard engineering methods such as concrete grouting or chemical grouting in the affected areas can mitigate the possible damages.   
All these options will be determined after a proper study. He highlights the importance of using proper DRR practices in this kind of situation.