earth science

Kermadec Trench

Kermadec Trench is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Kermadec Trench rather than just read about it. In short: The Kermadec Trench is a linear ocean trench in the south Pacific Ocean. It stretches about 1,000 km (620 mi) from the Louisville Seamount Chain in the north (26°S) to the Hikurangi Plateau in the south (37°S), north-east of New Zealand's North Island.

Key takeaways

Kermadec Trench belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kermadec Trench to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kermadec Trench from memory before moving on to harder problems.

Reference excerpt

The Kermadec Trench is a linear ocean trench in the south Pacific Ocean. It stretches about 1,000 km (620 mi) from the Louisville Seamount Chain in the north (26°S) to the Hikurangi Plateau in the south (37°S), north-east of New Zealand's North Island. Together with the Tonga Trench to the north, it forms the 2,000 km (1,200 mi)-long, near-linear Kermadec-Tonga subduction system, which began to evolve in the Eocene when the Pacific plate started to subduct beneath the Australian plate. Convergence rates along this subduction system are among the fastest on Earth, 80 mm (3.1 in)/yr in the north and 45 mm (1.8 in)/yr in the south.

Geology The Kermadec Trench is one of Earth's deepest oceanic trenches, reaching a depth of 10,047 metres (32,963 ft). Formed by the subduction of the Pacific plate under the Indo-Australian plate, it runs parallel with and to the east of the Kermadec Ridge and island arc. The Tonga Trench marks the continuation of subduction to the north. The Kermadec Trench has a southern continuation in the turbidite-filled Hikurangi Trough, but a series of seamounts on the Australian plate act as a dam and prevents this turbidity from reaching the sediment-starved Kermadec Trench. Debris from a larger subducted seamount probably dammed the trench from 2 Ma to 0.5 Ma and similar events probably redirected sediments in similar ways before that. Two oceanic plates meet at the Kermadec Trench which is located far from any larger landmass. Because of this, the Pacific plate as well as the trench itself is only covered by c. 200 m (660 ft) of sediments. The trench is almost perfectly straight and its simple geometry is the result of the uniformity of the subducting sea-floor. This sea-floor formed at the extinct Osbourn Trough, located just north of the Louisville Seamount Chain. Abyssal hills on the subducting sea-floor are oriented perpendicular to the old spreading centre and the sea-floor is 72–80 Ma near the Louisville seamounts at the northern end and more than 100 Ma near Hikurangi Plateau at the southern end. There are no seamounts on the sea-floor near the Kermadec Trench except one sitting on the trench slope at 31.50°S 176.45°W / -31.50; -176.45 which has been dated to 54.8±1.9 Ma. The Hikurangi Plateau formed part of the Ontong-Java-Manihiki-Hikurangi large igneous province (LIP) during the Ontong Java Event 120 Ma. The Manihiki Plateau is currently subducting under the southern part of the Kermadec Arc but most of it has already been subducted. The LIP-arc collision occurred 250 km (160 mi) north of its present location, but oblique plate convergence has migrated the subducted plateau southward.

Fauna In 2012, deep sea researchers discovered individuals of a species of giant amphipod at the trench's lowest depths. Unlike most amphipods, which are approximately 2.5 cm (1 inch) long, this species reaches up to 34 cm (13 inches) in length, and is milky-white. The second-deepest fish, the hadal snailfish Notoliparis kermadecensis, is endemic to the trench and occupies a very limited depth range, 6,472 to 7,561 m (21,234 to 24,806 ft). A species of pearlfish, Echiodon neotes, has been caught in the Kermadec Trench at a depth of 8,200–8,300 m (26,900–27,200 ft). All other known pearlfishes live in the range 1,800–2,000 m (5,900–6,600 ft) and the presence of E. neotes at this depth remains unexplained.

Exploration In May 2014, the Nereus, an unmanned research submarine operated by the Woods Hole Oceanographic Institution (WHOI), imploded due to high pressure at a depth of 9,990 metres while exploring the Kermadec Trench. In December 2022, a research team from the Chinese Academy of Sciences and National Institute of Water and Atmospheric Research reached the bottom of the Scholl Deep nearly 10 km below the surface.

See also Kermadec Islands Monowai Seamount Tonga-Kermadec Ridge

References Notes

Bibliography

External links "Kermadec Trench". Woods Hole Oceanographic Institution. Retrieved 9 April 2017. An animation of a 3D model of the Kermadec Trench

Illustrations

Worked examples

Example 1 — a first encounter with Kermadec Trench

Start with the simplest possible case. Write down what Kermadec Trench claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Kermadec Trench before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Kermadec Trench ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Kermadec Trench

In research: Kermadec Trench appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Kermadec Trench in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Kermadec Trench is common in secondary-school and first-year university syllabi. It links to neighbouring topics Geography of the Kermadec Islands, Geography of the New Zealand seabed, Oceanic trenches of the Pacific Ocean, so understanding it makes those chapters shorter.
In everyday life: Look for Kermadec Trench outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Kermadec Trench in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kermadec Trench means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Kermadec Trench out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kermadec Trench in simple terms?

Why does Kermadec Trench matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Kermadec Trench?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Kermadec Trench.