雅思阅读 059 · Here's What Stops Huge Earthquakes in Their Tracks

改编自 Scientific American（Jacek Krywko, 2026）。题型：T/F/NG + 填空。难度：中等偏上（Passage 2，约 700 词）。

---

🎧 课文朗读音频（约 1 分钟）

正文 Passage

On April 20 residents of northeastern Japan were rattled by a massive magnitude 7.7 earthquake off the coast. They were warned of possible tsunamis, as well as a slim chance of a magnitude 8 or higher "megaquake" in the coming days.

A study published just a few days later in Science investigates how such megaquakes evolve, what can eventually stop them and how we can predict their destructive power.

How earthquakes start

An earthquake starts deep underground when huge tectonic forces cause stress to build up along a fault line: a massive fracture in Earth's crust where blocks of rock have shifted and moved past one another.

If this accumulated stress overcomes the friction holding the rocks together, the fault slips, and a rupture rapidly spreads along it, generating powerful seismic waves that cause the ground to shake.

This process continues until the spreading rupture reaches an area of low stress and slowly loses momentum or until it hits a physical barrier underground — such as a change in the ground's makeup or trapped high-pressure fluid — that makes it stop instantly like a speeding train crashing into a concrete wall.

The stopping phase

Not all underground barriers will stop a rupture. But if one does, the impact creates a signature travelling in the opposite direction called a stopping phase.

"When the rupture is going fast and encounters some barrier that suddenly makes it stop, it sends out a shock wave," says study co-author Jesse Kearse, an Earth scientist at Victoria University of Wellington in New Zealand.

A human standing above such a barrier would first feel the ground move in the same direction as the rupture and then sharply jump back in the opposite direction.

"It's like you're in a car and the brakes suddenly engage, and you snap back in your car seat," Kearse says.

The research

But observational data showing that signature have been lacking.

Kearse and his colleague Yoshihiro Kaneko, a geophysicist at Kyoto University, hunted for it in the seismic and geodetic data registered by sensors in the paths of 12 large earthquakes across the globe.

Five of the earthquakes the researchers studied were equipped with enough sensors along the fault that the team could isolate a stopping phase.

They also found that certain near-surface features, such as softer rock layers above the stopping phase, can further enhance the signal, leading to more severe shaking of the ground at the surface.

Every barrier a rupture hits on its way works as a checkpoint. If the barrier holds, it stops the earthquake, which can end up as a minor, localised event. But if the advancing rupture has enough energy to shatter through the checkpoint, it spills over into the next fault segment, potentially cascading into a megaquake.

Future applications

Now that they know how to identify a stopping phase signature, the researchers can pinpoint these phases in past earthquakes' data to map out underground barriers and assess how much energy they can absorb.

"There's still a lot of research to do before the new findings help to build more accurate earthquake models," Kearse says.

Kearse and Kaneko limited their study to strike-slip earthquakes, in which two blocks of rock slide horizontally past each other, because there are simply more data for them.

"The obvious continuation of this work is to make it more general," Kearse says. "But we expect this stopping mechanism is a common feature of the earthquake process that does apply to thrust events, too. We just cannot confirm that yet."

---

题目 Questions

Questions 1-5: T/F/NG

1. The Japan earthquake on April 20 was magnitude 7.7.

2. Earthquakes stop only when they reach an area of low stress.

3. A stopping phase travels in the same direction as the rupture.

4. Kearse and Kaneko studied 12 large earthquakes globally.

5. The study covered both strike-slip and thrust earthquakes.

Questions 6-10: Complete the notes. Choose NO MORE THAN TWO WORDS.

• The study was published in the journal (6) ____________.
• Jesse Kearse is at Victoria University of (7) ____________.
• Yoshihiro Kaneko is at (8) ____________ University.
• Softer rock layers above the stopping phase can further (9) ____________ the signal.
• The researchers limited their study to (10) ____________ earthquakes.

---

答案 Answers

题号	答案
1	TRUE
2	FALSE (or hits a barrier)
3	FALSE (opposite direction)
4	TRUE
5	FALSE (only strike-slip)
6	Science
7	Wellington
8	Kyoto
9	enhance
10	strike-slip

---

核心词汇

earthquake / fault line / rupture / stopping phase / seismic waves / tectonic / strike-slip / megaquake / Kearse / Kaneko