2022-2023学年英语周报七年级第37期答案汇总

Solutions don’t come easily, but they are key

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Solutions don’t come easily, but they are key to a livable future. While it’s too late to avoid the impacts of climate change, we can avoid the worst of those impacts by investing more in such nature-based water solutions.When a chunk of ice fell from a collapsing glacier(冰川)on the Swiss Alps’ Mount Eiger in 2017, part of the long deep sound it produced was too low for human ears to detect. But these vibrations held a key to calculating the ice avalanche’s(崩塌)critical characteristics.

Low-frequency sound waves called infrasound that travel great distances through the atmosphere are already used to monitor active volcanoes from afar. Now some researchers in this field have switched focus from fire to ice: dangerous blocks snapping off glaciers. Previous work has analyzed infrasound from snow avalanches but never ice, says Boise State University geophysicist Jeffrey Johnson. “This was different,” Johnson says. “A signature of a new material has been detected with infrasound.”

Usually glaciers move far too slowly to generate an infrasound signal, which researchers pick up using detectors that track slight changes in air pressure. But a collapse—a sudden, rapid breaking of ice from the glacier’s main body—is a prolific infrasound producer. Glacial collapses drive ice avalanches, which pose an increasing threat to people in mountainous regions as rising temperatures weaken large fields of ice. A glacier “can become detached from the ground due to melting, causing bigger break— offs,” says University of Florence geologist Emanuele Marchetti, lead author of the new study. As the threat grows, scientists seek new ways to monitor and detect such collapses.