After a thunderstorm on the 29 Aug I noticed that cell phone reception on my phone dropped from 1-2 bars to no bars, but not no service (so the occasional SMS does get through eventually).

Previously when the nearest cell tower was out of service for 15 days I had no service at all, but currently it seems to be partially working.

I'm assuming a tower has multiple aerials covering different directions, so is it possible for one to be degraded or not working, and if so would there be any monitoring in place that would report this sort of problem automatically?

The tower in question is Spark WAIOTAMA (gis.geek.nz) or Spark Maungakaramea when listed on the Spark Outages page. I am located about 11km north of the tower.