Missing:
that took place in...
or
that occurred in...
or something else?

or:
that struck Armenia etc.

Thanks Eldad, the verb I forgot was "struck" :-)

:-)
It came to my mind only as a third option, but I'm glad I managed to guess your original intention... ;-)

BTW, I must admit it's a bit difficult for me to guess what you wish to write, as I cannot deduce that from your native language. Here's a language I have great difficulties to understand or even grasp the spirit of what it intends to say, as it seems I know practically nothing about it... ^v^

If it were "that took place in 1988", I would have said "ay d-yellan". Verb "ili" is "to be" - its participle is "yellan" - we use the participle after relative pronoun "ay":

Tizenzelt ay d-yellan deg 1988.
The earthquake that took place in 1988.

Other examples with participles:

Look at these sentences:

Tom yeldey tawwurt.
Tom opened the door.

D Tom ay iledyen tawwurt. ("ldey" [to open] is in the participle form)

Tom opened the door (It's Tom who opened the door).

In French, it would be:
C'est Tom qui a ouvert la porte.

"D" - It's
"Tom" - Tom
"ay" - who
"iledyen" - opened
"tawwurt" - the door

*************

I think that with a very rich corpus of Amazigh, some rules will start to become transparent to readers who read the same kind of sentences.

I too try to guess some rules in some languages I don't know and that are particularly difficult (like Lithuanian). I can understand parts of sentences in these languages and guess the meaning, but any translation will certainly need a native speaker's check.

*******

Let's come back to the Amazigh sentence:

Tizenzelt ay d-iwten deg 1988.
The earthquake that struck in 1988.

Even in this sentence, verb "wet" [to strike, to hit, to beat] is in the participle form (ay d-iwten). Verb "wet" is a very polysemic verb in Amazigh. It is also used in many different idioms and expressions:

Iwet-d wenẓar (it rained - literally "the rain hits/strikes")
Iwet-d wedfel (it snowed)
Iwet-d webruri (it hailed)
Iwet-d deg Tom (he spoke ill about Tom)
Etc.

Thanks, things start to be more apparent now, after you explain those basic words and grammatical particles.

I'll continue now with the paper I need to translate, but I'll refer to your notes later and try to memorize them.

You're welcome Eldad, by the way, I'm preparing an online dictionary that will include Amazigh conjugation. Once I finish the conjugation, you'll be able to know the meaning of any conjugated verb in my Tatoeba sentences, no matter in which form it is. As for the Tatoeba corpus, it will allow you to know how each verb is used in different contexts ^^ The Internet is wonderful :-)

That would be great, Amastan!

Indeed, it will be great!
Thanks, it's good we have a fanatic like you! ;-)

Hahahahaha :-) Thank you my friends :-D