TEHRAN — Iranians dug through rubble in a frantic search for survivors on Monday, after a powerful earthquake struck near the Iraqi border, killing more than 500 people and injuring thousands of others in the world’s deadliest earthquake so far this year.

The quake, recorded at 9:48 p.m. on Sunday, was felt as far away as Turkey and Pakistan. The epicenter was near Ezgeleh, Iran, about 135 miles northeast of Baghdad, and had a preliminary magnitude of 7.3, according to the United States Geological Survey. Seismologists in the country said it was the biggest quake to hit the western part of Iran.