Earthquake intensity 8.1 or 7.5?

Updated October 27, 2015

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USGS estimates the quake’s intensity at 7.7, then revised it down to 7.5 on the Richter scale.—AP/File
USGS estimates the quake’s intensity at 7.7, then revised it down to 7.5 on the Richter scale.—AP/File

ISLAMABAD: The earthquake that shook Afghanistan, Pakistan and parts of India on Monday afternoon occurred at 2:09pm Pakistan time and, according to the Pakistan Meteorological Department, measured 8.1 on the Richter scale.

The massive quake originated around 150 miles below the earth’s surface, with the epicentre located in mountains of Hindu Kush in the Badakshan province of Afghanistan.

“The earthquake was caused by the collision of the Indian and Eurasian tectonic plates,” PMD spokesperson Mohammad Hanif said.

Though the duration of shockwaves varied in different areas, the average duration of the tremors was around one-and-a-half minutes.

Apart from the main quake, at least 12 aftershocks were recorded, most of them mild in intensity. However, the most severe aftershock was recorded at 2:49pm PST and measured 5.3 on the Richter scale.

Within minutes of the earthquake, the US Geological Survey (USGS) estimated the quake’s intensity at 7.7, then revised it down to 7.5 on the Richter scale.

However, an official from the Met Office said that the USGS readings were different from PMD’s because they were monitoring the situation from mainland America, as USGS did not have a station in Afghanistan or Pakistan.

“On the other hand, PMD has bases to observe seismic activities in Cherat and Chitral. There is also an advanced station in the Pattan area of Swat, since these areas fall in the active seismic zone,” the official said.

After the quake, most cellular users in the central and northern parts of the country faced a lack of connectivity for up to one hour. However, officials from cellular service providers denied that there was a breakdown in connectivity.

“The problem was mainly due to congestion, as the worst-affected areas were business districts and commercial areas,” said a spokesperson for one of the largest mobile service providers in the country. “People began calling their loved ones who were away at work or in other areas,” he said.

He said that each cellular tower had a certain capacity, but if all the users in the area started calling at the same time from any one area, then the Radio Base Station (RBS) of that particular area would choke.

Dams and water reservoirs of the country reported no damage from the shockwaves, the Ministry of Water and Power announced on Monday evening.

Published in Dawn, October 27th, 2015

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