Dead Creatures Buried in The Ocean Could Influence Earthquakes, Scientists Say

The largest fault in the vicinity of New Zealand is called the Hikurangi subduction zone and is capable of causing earthquakes that can be felt in New Zealand. There could be a big impact on the next earthquake if tiny, ancient marine organisms are involved.

calcite deposits left behind by single-celled marine organisms tens of millions of years ago can control the level of movement between the Pacific plate and Australia plate, according to researchers.

The key is whether or not it can be dissolved. If it does, the plates can slide past each other more easily; if it doesn't, that blocks the plate movement, locking up energy that will later be released in a burst.

Carolyn Boulton is a structural geology professor at the Victoria University of Wellington in New Zealand.

It can be dissolved at room temperature. It gets harder to dissolution as the temperature increases.

In the depths of the subduction zone the temperature warms by 10o C for every kilometer. Calcite shells that aren't dissolved far beneath the surface could affect the movement of the fault.

The exposed layers of limestone, mudstone and siltstone on a local shoreline on the North Island are a proxy for the fault because it is hard to get to.

The rocks there are mostly made of foraminifera, a type of marine organisms. The next question is how much of this is in the subduction zone.

Boulton says that the amount and behavior of calcite from these organisms is a big piece of the puzzle.

The Hikurangi subduction zone can't be looked at up close because it's too deep. It's harder to predict the next big earthquake because the record of previous ones isn't as comprehensive and the knowledge of its condition isn't as thorough.

There is a 26 percent chance of a large earthquake in the next 50 years along this fault, one which could generate a large wave.

The study shows how plate movements can be slow and slight, or quick and large, and the more we know about the build-up of calcites underwater, the better we can figure out what's coming next.

Boulton says that these tiny, long-dead organisms can affect how two big plates interact.

The research has appeared in a journal.