You're right to raise this - I admit I was depending on Adela Collins' claim to this effect, and while she notes the LXX reading of that text (which is 63:19 - versification is different) it refers to "opening" rather than "splitting" as here (σχίζω), so sees as much difference as similarity. She doesn't mention the Hebrew. I actually think there is more difference between this and the present text than the NRSV's "torn apart" allows - i.e. the translators may be fishing for a direct parallel, and I didn't correct this above. Yet I think you're right to wonder about some resonance.
Could the heavens being "torn open" deliberately echo and respond to Isaiah 64:1 and following?
You're right to raise this - I admit I was depending on Adela Collins' claim to this effect, and while she notes the LXX reading of that text (which is 63:19 - versification is different) it refers to "opening" rather than "splitting" as here (σχίζω), so sees as much difference as similarity. She doesn't mention the Hebrew. I actually think there is more difference between this and the present text than the NRSV's "torn apart" allows - i.e. the translators may be fishing for a direct parallel, and I didn't correct this above. Yet I think you're right to wonder about some resonance.