To occur one after another; to happen in succession (often used for events that repeatedly occur).
最近、全国で火事が相次いでいる。
Recently, fires have been occurring one after another across the country.
年度末に事故が相次ぎ、部署で対策会議を開いた。
At the end of the fiscal year accidents occurred in succession, so the department held a meeting to discuss countermeasures.
新商品の発売が相次ぎ、店頭がにぎやかだ。
New products are being released one after another, making the shops lively.