KARACHI: While a serious tsunami threat from the Makran subduction zone looms over the Pakistan coast, one must not underestimate the threat from the Rann of Kutch fault which might have a devastating impact on Karachi, Badin and the Indian state of Gujarat.

This information was shared by Zahid Rafi, the director, earthquake monitoring at the Pakistan Meteorological Department (PMD) in Islamabad, at a seminar — Current status of hazard preparedness and risk mitigation for potential tsunami along the coast of Pakistan.

The event was organised at the NED University of Engineering and Technology in collaboration with the National Institute of Oceanography (NIO).

Starting off with a welcome address, NED University Vice Chancellor Prof Sarosh H. Lodi said that it was important to discuss the tsunami threat and take protective measures given the fast-paced infrastructural developments taking place in Gwadar.

He pointed out the Makran subduction zone, which extended east from the Strait of Hormuz in Iran to near Karachi with the length of about 900 kilometres, was the source of the second deadliest tsunami in the Indian Ocean in 1945, which claimed lives of hundreds of people only seven decades ago.

More than 90 per cent of damage to life, property and livelihood happened in the area along Pakistan’s coast, he said.

“Imagine the situation if, God forbid, the Karachi port is closed down for a week in case of a disaster like tsunami. At least we should know the kind of risks involved, status of our capacity and how could we collaborate to build up our knowledge and understand the issue better,” he said.

Giving a presentation on a recent PMD study on tsunami risk assessment carried out with the assistance of Cambridge University, Mr Rafi said that the Makran subduction zone was one of the least documented zones in the world. In this region, the oceanic crust of the Arabian Plate was being subducted beneath the continental crust of the Eurasian Plate.

According to Mr Rafi, the area of the subduction zone in Pakistan was more prone to earthquakes (as it had seen a number of such) as compared to the subduction zone falling under the jurisdiction of Iran.

“In his memoir, Portuguese explorer Vasco da Gama also talks about huge tidal waves causing devastation. While there is evidence of tsunamis affecting Pakistan and Oman, there is hardly such evidence on the western side [Iran].

“We can expect a big mega-thrust tsunami from the subduction zone locked in Pakistan’s territory. But, we can’t predict its occurrence,” he observed.

He also briefed the audience about the techniques and technologies used to measure the depth of the Makran subduction zone, which he said would be around 50km.

To a question, he said that there were less chances of Karachi being affected by tsunami, though its areas like Hawkesbay and Machhar Colony were vulnerable to the risk.

“What worries me more is the Rann of Kutch fault that had seen two major earthquakes in 1819 and 1845. The fact that a lot of time, around 200 years, has passed [since] these events, make their chances of recurrence stronger,” he explained.

Seismic data analyst Uzair Azam and physical oceanographer Ibrahim Zia, both representing the NIO, spoke about the role of oceanography in estimating net wave height and extent of inundation in case of tsunami.

According to them, seafloor topography and underwater topography both affect the tsunami’s intensity and dynamics.

“Pakistan’s coast faces high-wave action. Coastal areas are experiencing high erosion and many low-lying areas get inundated especially in the monsoon season or in case of an unusual event like last year’s super moon during which seawater intruded up to 20km inside Khubar Creek,” said Mr Zia.

He underlined the need for carrying out surveys to acquire proper data for hazard analysis and risk assessment along the coast.

Experts also pointed to the flawed fish harbours established along Balochistan coast which had led to massive coastal erosion.

Researcher Hira Ashfaq Lodhi of NED University’s Physics Department highlighted the need for risk and hazard mapping for better contingency planning in Pakistan’s case.

NIO director general Dr Asif Inam concluded with the remark that proper understanding of tsunami was not possible without understanding the dynamics of the Arabian Sea.

Published in Dawn, July 25th, 2017