The weekly chart along with 13 week RSI shows the extreme nature of the decline. There have been 2 other times when 13 week RSI was this low; June 1989 and September 2000.
Rallies of over 9,000 pips occurred within the next month on both occasions within the next 6 weeks before the GBPUSD dropped to a new low. Keep min mind that the historical readings are RSI on a weekly closing basis so we additional losses are possible this week before a reversal. Just be aware that the decline is extended and due for a major pullback.