It's being reported this morning that Taiwan Semiconductor Manufacturing Co. halted some chipmaking and evacuated plants after the biggest earthquake to hit its home island in 25 years, raising concerns about disruptions to the global tech supply chain.

Bloomberg reports that TSMC, the main contract chipmaker to Apple Inc. and Nvidia Corp., moved staff out of certain areas and said it’s assessing the impact of a temblor measuring 7.4 in magnitude off the east coast. Smaller local rival United Microelectronics Corp. also halted machinery at some plants and evacuated certain facilities at its hubs of Hsinchu and Tainan, it said in a statement.

Taiwanese firms from TSMC to ASE Technology Holding Co. make and assemble the vast majority of the semiconductors that go into devices from iPhones to cars, from factories vulnerable to even the slightest tremors. A single vibration can destroy entire batches of the precision-made semiconductors. TSMC shares slid 1.3%, while UMC was down nearly 1%.

The island’s tech firms are still assessing impact from the earthquake, which leveled dozens of buildings on its eastern side and killed at least four people. On Wednesday, TSMC said staff were beginning to return to evacuated sites though it stressed it was examining impact. Still, any halt in production threatens to upset a process that — especially for sophisticated semiconductors — can require uninterrupted seclusion in a vacuum for weeks on end, Barclays analysts wrote.

“Some of the high-end chips need 24/7 seamless operations in a vacuum state for a few weeks,” analysts Bum Ki Son and Brian Tan said. “Operation halts in Taiwan’s northern industrial areas could mean some high-end chips in production may be spoiled.” For more, read the full report by Bloomberg's Debbie Wu.