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Every time that Roger's machine
每一次 罗杰的仪器
measures the fault slipping,
测量断层的滑移
known as a creep event,
也被称作蠕变
this may help to calculate the amount of stress
可以帮助计算 在这座城市下面
that's building up beneath the city.
正在积聚的能量
Oh, we've got a creep event! How exciting.
我们检测到了蠕变现象 太高兴了
The black line here is, er, can you see that OK?
这条黑线是... 你看见了吗
So the black line is the temperature decrease
这条黑线显示 气温从仲夏
from mid-summer to... It's upside down, OK,
开始下降 上下颠倒了
we could actually turn it up the other way
我们可以这样来看
but let's do it like that,
还是这样吧
so there's the temperature decreasing as a function of time
气温的下降是由于季节的变化
and here is, er, a creep event
这个就是蠕变现象
where the fault suddenly starts slipping
当断层突然开始
at a few millimetres per second and
以每秒几毫米的速度滑移
then over the next day or two,
并持续一两天
in fact continuing for several weeks.
实际上会连续好几个星期
Even if you'd been standing on the fault,
就算你站在这个断层上
you wouldn't have noticed it
你都感觉不到
because it's really a very slow, quiet process.
因为它非常缓慢 悄然无声
So until people have put
所以 只有当人们将这种仪器
instruments like this on the ground,
放到地里
we had no idea that these things were occurring.
否则我们无法知道这一切的发生
