Remains of tiny creatures tens of millions of years old can affect the size The next devastating earthquake is in the Hikurangi subduction zone, New Zealand’s largest fault.
This region defines the boundary in which a file is located Pacific plate Sinking under the Australian plate. Large earthquakes greater than magnitude 8 can be generated in the region.
Dr. Caroline Bolton from Victoria University of Wellingtonleads a team of seismologists studying a cliff on the Hungara Fault, located on the fringes of the Hikurangi subduction zone.
Limestone, siltstone and mudstone layers in the Jurf near Tura, About 35 kilometers southeast of Martinborough, these compounds are a useful indicator of what’s happening in the offshore subduction zone, Bolton says in a statement.
Rocks similar to those found on the cliff were deposited on the sea floor between 35 and 65 million years ago, but their location makes them difficult to study. Instead, scientists can look at rocks on Earth to learn more about what’s going on under the sea.
All the rocks contain calcite from ancient times unicellular marine organisms Mainly foraminifera, such as plankton. We have found that calcite from these microorganisms can influence the movement in the subduction zone. These long-dead microorganisms could influence how two huge tectonic plates interact mechanically.”
Seismologists study a cliff on the Hungarua Fault, located on the fringes of the Hikurangi subduction zone.
It says that if calcite in rocks can be dissolved, like sugar in teaThe defect may be weak and easy to slide without an earthquake. However, if calcite cannot be dissolved, the fault can “lock up”, storing energy that would be released in a large earthquake.
“Calcite melts faster when it is highly stressed and when temperatures are cooler. It melts more easily at lower temperatures, for example room temperature. But it becomes more difficult to melt as the temperature rises, for example deep in the earth,” as he says.
“In the subduction zone, the temperature rises more slowly than on land, only about 10°C/km. So the fault is really sensitive to what calcite does, those shells of ancient dead marine organisms. The amount and behavior of calcite from these organisms is a big part. From the puzzle of what size the next earthquake could be.”
Bolton says the Hikurangi subduction zone still holds many mysteries that scientists can solve. “Geologists who study the Alpine fault and other faults on Earth can examine it up close. But seeing inside the Hikurangi subduction zone requires expensive drilling equipment. This means that our record of previous large earthquakes in the region is not good.”
Scientists predict that there is a 26% chance of a major earthquake in the next 50 years at the southern margin of the Hikurangi subduction zone.
“Our observations show that the shallower part of the subduction zone can accommodate plate motions by slipping slowly, or slipping quickly in large, destructive earthquakes. What we really want to know is: Are there slow slip events that we haven’t seen? Revealed?” says Bolton. Do rocks move without earthquakes or are they already confined? This will help us tell us what might happen in the next earthquake.”
A large earthquake along the subduction zone can generate a great tsunamiwhich have been found in geological fossils and the fossil record along the eastern shores of New Zealand’s North and South Islands and across the Cook Strait.
Scientists predict that there is a 26% chance of a major earthquake in the next 50 years at the southern margin of the Hikurangi subduction zone.
The results of the research were published in the journal Lithos.
