String of quakes hit worldwide, but it's a coincidence says expert

Geonet seismologist John Ristau said the closeness in timing of the earthquakes was a coincidence.

A 4.7 magnitude earthquake in California this morning is the latest to hit after a string of shakes across the globe.

The quake struck at 11.31am (local time) 24km from Soledad. In a statement the US National Tsunami Warning Center said based on earthquake information and historic tsunami records, the earthquake was not expected to generate a tsunami.

It followed a 6.5 earthquake that rocked Costa Rica yesterday, and a devastating 7.3 quake that killed more than 400 people in the border region between Iraq and Iran on Sunday.

Earthquakes have hit world wide over the past five days.

It hit at 9.48pm Iran time, just as people were going to bed. The worst damage appeared to be in the western Iranian province of Kermanshahin - the Kurdish town of Sarpol-e-Zahab.

New Zealanders were also jolted awake on Sunday night, when a 4.8 quake hit at 11.28pm in the Cook Strait, 30km west of Wellington. Thousands reported feeling the shake.

Geonet seismologist John Ristau said the closeness in timing of the earthquakes was a coincidence.

"You can get cases where large earthquakes trigger smaller ones nearby, but these are quite spread apart."

Ristau said there was no evidence that earthquakes of any magnitude were occurring more frequently.

He also noted compared to other earthquakes, California's 4.7 and New Zealand's 4.5 shakes were relatively small and quite common. Even the Costa Rica quake was not uncommon for South America, he noted.

"Earthquakes are random and chaotic, there's fluctuations in when they occur... Over a long term period, it averages out and you'll still get about the same number of different types of magnitude earthquakes per year."