揺れはゆっくりと弱くなりはじめた。

shaking; shake; jolt; jolting; vibration; tremor; flickering; unsettledness; instability; vacillating; wavering; existence of multiple spellings, pronunciations, usages, etc. for a single word

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

slowly; at ease; restful

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

weak; frail; delicate; tender; unskilled; weak (wine)

to become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...