The quake also appears to have been related to a new island that suddenly emerged out of the Arabian Sea at the same time, more than 200 miles away.
The 7.7 magnitude quake lasted almost a minute when it struck at 4:29 p.m. local time.
Terrified residents rushed into the streets, including in the Pakistani port city of Karachi, 175 miles to the southeast of the epicenter.
Hundreds of mud-and-brick houses collapsed or were damaged in the shaking across Balochistan province, where the quake was centered.
Several strong aftershocks inflicted further damage.
Meanwhile, residents in the coastal town of Gwadar, more than 200 miles southwest of the epicenter, say they saw a solitary island emerge from the Arabian Sea just offshore at about the same time the initial quake struck.
Older residents told reporters that such an island also emerged following a 1968 temblor, but disappeared within a year.
Seismologists suspect the latest new island will also be a temporary feature and was caused by jets of mud, sand and water that were thrust upward by the force of the strong seismic movement. Others say a mud volcano was forced into eruption to create the island by shockwaves from the distant earthquake.