Meaning:
“瞳孔” means “the pupil of the eye,” and “地震” means “earthquake.” The term, which is literally translated as “an earthquake in one’s pupils,” was first used in 2018 to caption the reaction of singer-actor Wu Chun when he was asked about the scandal of Aaron Yan’s crush on Jiro Wang during a TV variety show in Taiwan. The three were previously members of the same boy band Fahrenheit. The TV footage showed a close-up shot of Wu’s eyes, obviously shocked by the question. Chinese netizens now use the term to describe a facial expression and feeling of shock. They’ve also come up with an emoticon — ( ; ; @_@ ) — to represent this term.
Example:
A: 你听说玛丽和杰克又和好了吗？
Nǐ tīngshuō mǎlì hé jiékè yòu héhǎo le ma?
Did you hear that Mary and Jack got back together again?
B: 我周末撞见他们一起看电影，牵着手秀恩爱，当时就瞳孔地震了。
Wǒ zhōumò zhuàngjiàn tāmen yīqǐ kàndiànyǐng, qiānzheshǒu xiùēn’ài, dāngshí jiù tóngkǒng dìzhèn le。
I ran into them at the movie theater over the weekend. Seeing them hand in hand and packing a lot of PDA, I was so shocked! (PDA — Public Display of Affection)