It's well known that a large meteorite hitting the Earth would not be good news, as it would cause earthquakes, tsunamis and firestorms.
However, scientists have created a new model for predicting the impact of such collisions that shows the devastation wouldn't be anywhere near as severe as previously thought.
Scientists from the University of Munich argue that previous predictions of impact damage assume the Earth is smooth and spherical - but it's actually elliptical with huge peaks and troughs, which would help to diffuse the resulting seismic waves.
Research leader Matthias Meschede said: "After a meteorite impact, seismic waves travel outward across the Earth's surface like after a stone is thrown in water."
"For the Earth, these calculations are usually made using a smooth, perfect sphere model, but we found that the surface features of a planet or a moon have a huge effect on the aftershock a large meteorite will have, so it's extremely important to take those into account."
Mr Meschede's team used their model to produce a fresh simulation of the meteorite crash that wiped out the dinosaurs 65million years ago and caused the huge Chicxulub crater, which can be seen from space.
It was the equivalent of two million hydrogen bombs going off - yet the Munich team have downplayed its effects, claiming that the tsunamis and earthquakes that resulted were enough to wipe out the dinosaurs, but the shock-waves "that caused them would have been weakened by the planet's landscape".
Mr Meschede added: "Our results go beyond Chicxulub. We can, in principle, now estimate how large a meteorite would have to have been to cause catastrophic events. Our model can be used to estimate the magnitude and effect of other major impacts in Earth's past."
Tomorrow an asteroid the size of four football pitches called 2005 YU55 will pass between the Earth and Moon.
If something that size was to slam into the Earth it would cause a 2.5mile-wide crater, a magnitude 7.0 earthquake, and if it hit water a 70-foot high tsunami would spread within 60 miles of the crash site.


据英国《每日邮报》11月7日报道，众所周知，大型陨石撞击地球可不是什么好消息，因为它会引发地震，海啸以及大火。

然而，科学家们已经建构出了新的模型来预测这种撞击的影响，结果显示这种破坏并不是如人们之前所预想的那么严重，不是在你附近的任何地方都会发生。

来自慕尼黑大学的科学家说，之前对于撞击破坏性的预测，假设地球是表面平滑的球体--但实际上它是椭圆的，并且地表上都是起伏的波峰和波谷，这将有助于化解撞击所产生的地震波。

研究负责人马蒂亚斯•梅舍德说："陨石撞击后，地震波会通过地球的表面向外扩散，就像是把石头扔进水里。"

"对于地球来说，相关运算通常会采用平滑、完美的球体模型，但我们发现行星或者月球的地表特征会对大型陨石撞击带来的余震产生重大影响，所以在地球相关运算时把地表特征因素考虑在内是非常重要的。"

梅舍德先生带领的研究团队运用他们的模型重新模拟了6500万年前的陨石撞击，那次陨石撞击使得恐龙灭绝，并造成了巨大的希克苏鲁伯陨石坑，在遥远的太空也能看见。

那次撞击的力量相当于同时引爆两百万颗氢弹--不过慕尼黑研究小组已经淡化其影响，并声称，由此引发的海啸和地震虽然足以毁灭恐龙，但冲击波已经被地球的地表特征削弱。


梅舍德先生还补充道："我们的研究成果不仅用于希克苏鲁伯陨石坑。原则上，我们可以估算陨石撞击会引发多大程度的灾难性事件。我们的模型可以被用于估计地球过去历史上曾有撞击的范围和影响。"

明天（11月8日）一颗名为2005 YU55的四个足球场大小的小行星将通过地球和月球之间。

如果像这样大小的物体撞击地球的话，会形成2.5英里宽的陨石坑，引发里氏7.0级地震，如果它撞击入水，将会有70英尺高的海啸波及至撞击点周围60英里的范围。

• anywhere [´eniweə] ad.无论何处；任何地方 (初中英语单词)
• severe [si´viə] a.严厉的；苛刻的 (初中英语单词)
• previous [´pri:viəs] a.先，前，以前的 (初中英语单词)
• actually [´æktʃuəli] ad.事实上；实际上 (初中英语单词)
• planet [´plænit] n.行星 (初中英语单词)
• extremely [ik´stri:mli] ad.极端地；非常地 (初中英语单词)
• estimate [´estimət, ´estimeit] n.估计；评价 vt.估价 (初中英语单词)
• previously [´pri:viəsli] ad.预先；以前 (高中英语单词)
• outward [´autwəd] a.外面的 ad.向外 (高中英语单词)
• sphere [sfiə] n.圆体；天体；范围 (高中英语单词)
• equivalent [i´kwivələnt] a.相等的 n.同等物 (高中英语单词)
• hydrogen [´haidrədʒən] n.氢 (高中英语单词)
• earthquake [´ə:θkweik] n.地震；大变动 (高中英语单词)
• diffuse [di´fju:s] v.散布，传播；扩散 (英语四级单词)
• magnitude [´mægnitju:d] n.宏大；重要性；大小 (英语四级单词)
• impact [´impækt] n.影响，作用；冲击 (英语六级单词)
• munich [´mju:nik] n.慕尼黑 (英语六级单词)
• crater [´kreitə] n.火山口；弹坑 (英语六级单词)