Over the last 4 weeks my site has seen a steady Year on Year increase in traffic from google organic searches as a result of a link building campaign which had boosted ranking for 5-6 keywords/phrases and consolidated ranking for 6-7 previously well ranked words and phrases.
And on monday Google updated our PR to PR4.
However, today i noticed that traffic from google organic was 50% lower than previuos days in the week and on further inspection all but 1 out of 12 key phrases/words that appeared on the 1st page of the SERPS as late as wednesday 20th October had been relegated to as low as the 9th page.
Even the phrases that had ranked in the 1st page of the SERPs for over 2 years were no longer there and some of the landing pages for many keyphrases/words changed to irrelevant pages.
I also check the incoming links to the site using Yahoo Site Explorer and they have been reduced by 50% since i last checked on wednesday 20th October.
Does anyone know what is the cause of this?