雅思阅读 101: When the Ocean Gives a Few Minutes' Notice（大海提前几分钟的警告）

改编自 NOAA Research / US Tsunami Warning Centers（2025年）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://research.noaa.gov/how-30-years-of-noaa-research-led-to-one-very-accurate-and-timely-tsunami-forecast/

Reading Passage

A. The Indian Ocean tsunami of 2004 is remembered as a natural catastrophe, but it was also a technological one. A vast undersea earthquake off Sumatra lifted the sea floor by several metres, displacing an immense slab of ocean and sending waves racing outward at the speed of a jet. In the open ocean the waves were barely a metre high — invisible to ships — but as they reached shallow coasts they reared up and swept ashore without warning, killing hundreds of thousands. The cruel detail was this: the Pacific already possessed a network of tsunami sensors and warning centres; the Indian Ocean possessed none. A disaster that unfolded over hours struck coasts that had no way to know it was coming. The tragedy is the reason the modern science of tsunami forecasting looks the way it does, and why the decades since have been spent building eyes in the deep that the 2004 coastlines lacked. It was, above all, a lesson in what happens when a hazard is known but nobody is listening for it.

B. The central difficulty is that a tsunami is easy to mistake for nothing at all while it is still at sea. In deep water the wave may stretch a hundred kilometres from trough to crest but stand only a few centimetres above the surrounding surface; to a mariner it is indistinguishable from a normal swell. Earthquake sensors on land know that the sea floor has moved, but a quake does not always produce a tsunami, and Its magnitude alone cannot say how big the wave will be, and whether one will arrive at all. A big earthquake, in short, is not automatically a big tsunami. A large earthquake far from the coast may send nothing dangerous; a smaller one nearby may generate a wall of water. Forecasters needed a way to listen to the open ocean itself — to confirm that a wave had actually formed, and to measure its height — before anyone could responsibly raise an alarm thousands of kilometres away. A false warning sends millions fleeing needlessly; a missed one does the opposite. The forecaster's dilemma is to tell, within minutes, which earthquake is which — to separate the quake that will merely rattle windows from the one that will send a wall of water across the sea.

C. That listening device is the system known by its acronym, DART — Deep-ocean Assessment and Reporting of Tsunamis. Each station pairs two instruments. Anchored to the seabed at depths of a thousand to six thousand metres sits a bottom pressure recorder, so sensitive that it detects the change in overlying water pressure when a wave crest passes overhead, a change equivalent to a rise of less than a centimetre. The recorder cannot radio through water, so it sends its readings by an acoustic signal up to a companion buoy bobbing on the surface, which relays them by satellite to shore-based warning centres within minutes. Each station is, in effect, a sentinel that stays silent through calms and storms alike until the one event it was built to report finally arrives. The American network alone runs to several dozen such stations, part of a wider international array strung across the Pacific and increasingly, after 2004, across the Indian Ocean as well. Each station is, in effect, a watchman on the seabed, silent for months and then reporting, without fail, the moment the sea above it moves.

D. A raw pressure reading, however, is not a forecast. The warning centres combine it with decades of pre-computed simulations. Because the physics of how a displaced patch of ocean floor generates a wave is well understood, forecasters have stored thousands of model "scenarios" — waves arising from an earthquake of this size, at this location, of this shape. When real data arrive, analysts match the observed arrival time, height and period against those stored simulations to infer the most likely source: where the sea floor moved, and how much. The result is a reasoned estimate of which coasts are threatened and how high the water will run, rather than the blanket panic of a raw earthquake alert. The system proved its worth in 2022, when a violent volcanic eruption near Tonga generated a wave whose arrival time and height were predicted with striking precision, buying the hours that made an orderly evacuation possible. Where the 2004 coast had heard nothing, a modern shoreline now hears the wave coming, and hears it while it is still far out to sea. The centuries-old art of predicting an earthquake had, by the 2020s, grown into a quantitative exercise in reading the deep ocean the moment it stirred.

E. Yet even a perfect sensor network cannot outrun physics. DART data are most valuable for distant tsunamis, where the wave's journey across an ocean buys several hours of evacuation time. A tsunami born off a city's own shoreline, however, may reach land within minutes — too quickly for any buoy in deep water to report and for any official warning to be issued. For those events, resilience has to mean something other than a technology: it means coastal communities that understand the natural warning signs — a sudden recession of the water, a distant rumble like a train, the sea withdrawing to expose the seabed — and that have kept low-lying shorelines free of permanent buildings. It also means drills, signs and maps, because no buoy can outrun a wave that has already reached the shallows. The most advanced buoy in the world, in the end, only buys the time to act; Whether a community uses that time still depends on whether it has planned for the day the ocean speaks. Technology, in the end, only translates the sea's warning; it cannot make people listen.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. Why a wave at sea looks like nothing at all ii. The two-part device that hears the deep iii. Turning a pressure blip into a forecast iv. The limits that no network can overcome v. The 2004 catastrophe as a technological failure vi. The business of building offshore buoys vii. Why earthquakes never cause tsunamis

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What made the 2004 Indian Ocean disaster partly a "technological" failure? A. The earthquake sensors were all powered down. B. The Indian Ocean had no real-time tsunami sensing network. C. Ships deliberately ignored the waves. D. The coasts had no roads for evacuation.

6. Why is a tsunami hard to detect in deep water? A. It emits a powerful magnetic field. B. It is long but only centimetres high and looks like a normal swell. C. It travels too slowly to measure. D. It freezes the surface solid.

7. How does a DART bottom pressure recorder transmit its data? A. By cable laid on the sea floor to the nearest city. B. Acoustically to a surface buoy, then by satellite to shore. C. By wireless telephone to a passing ship. D. It stores data for months before recovery.

8. How do warning centres turn observations into a forecast? A. By guessing from the air temperature. B. By matching real readings against thousands of pre-computed simulations. C. By waiting for the wave to arrive at the first beach. D. By interviewing fishermen who saw it.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. In the open ocean the 2004 waves were barely a metre high.
10. A bottom pressure recorder can detect a water-height change of less than a centimetre.
11. DART buoys can always give several minutes' warning for a tsunami arriving from the nearby shore.
12. A sudden retreat of the sea is mentioned as a natural warning sign.
13. The United States has no tsunami warning centres of its own.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

A DART station pairs a seafloor pressure recorder with a surface (14) __________; forecasters match its readings against pre-computed simulations to infer the earthquake's (15) __________.

答案与解析

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