The earthquake rattled Paraparaumu at 8:13am.
"There are major faults in low-seismicity areas that could produce a major event."
Thousands of Kiwis reported feeling the shake within minutes.
An earthquake rocked western Afghanistan on Monday, destroying hundreds of homes
The quake struck 90km west of Te Anau.
"So that's the reason we felt it down the coast."
The slow-slip event began in mid-September and experts have recorded six centimetres of movement at the plate boundary so far.
The quake hit just before 4am.
"If another large aftershock occurs it can re-energise the system."