Pakistan's Chief Meteorologist Officer Mohammad Riaz said the earthquake was measured at 7.2 on the Richter Scale and its origin was 150 kilometres west if Khuzdar in Balochistan province.
However, the US Geological Survey measured the tremor at 6.8 on the Richter Scale. Tremors were felt in provincial capitals Karachi and Quetta. All the local television channels showed people rushing out of their offices in Karachi.
"The tremors were not so strong as last time but one could still feel the chairs moving and tables shaking," Adnan Ahmed a employee of a media group said.
He said the tremors could be felt in major cities like Karachi, Quetta, Larkana, Jacobabad, Khairpur, Naseerabad, Sukkur, Mustung and Kharan.
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Rescue teams are still to reach several remote areas, including the worst-hit Balochistan's Awaran district near the epicentre of Tuesday's temblor.
While the official death count stands at 515, unofficial figures are as high as 700, with more than 800 injured. The earthquake left more than 50,000 people homeless in these areas.
The quake-hit area was also rocked yesterday by a massive aftershock measuring 5 on the Richter scale. Pakistan's met office said the epicentre of the aftershock was in Ormara and its depth was around 10 km.
A map showing the damages was uploaded by ISPR chief Maj Gen Asim Bajwa last night via twitter to "just to give an idea about the extent of damage".
Meanwhile, an army helicopter carrying relief goods to the quake-hit areas was fired at in Mashkay area of Awaran district by suspected militants yesterday. The helicopter was not damaged in the attack.
Security personnel accompanying a team of doctors for relief operations were fired at on Wednesday.
Though the army and Frontier Corps have moved 1,000 troops in the worst-hit areas, it is feared that people may still be trapped under the debris of thousands of collapsed mud homes.
The area near the epicentre is a stronghold of Baloch nationalist militants.