godan verb (-gu), intransitive verb
Physical use for something large or foundational shaking or seeming unstable. It is more written or dramatic than the everyday verb 揺れる.
地震で大地が揺るいだ。
The ground shook in the earthquake.
godan verb (-gu), intransitive verb
Common figurative use for confidence, belief, status, authority, or foundations becoming unstable; also frequent in the negative form 揺るがない, meaning unshaken or unwavering.
その証言で彼の立場が揺るいだ。
His position was shaken by that testimony.
どんな批判にも彼女の信念は揺るがなかった。
Her convictions did not waver in the face of any criticism.