津 波 注 : 天津,水皮曰波
Animation – see the [Quicktime] file 106293main_MISR_India_26Dec2004
www.hko.gov.hk/gts/equake/tsunami_mon_c.htm
最近修訂日期: <2004年12月29日>
香港海嘯的監測
大部分的海嘯是由海底地震所引致。由於香港的地理位置，菲律賓群島及台灣阻隔了大部分太平洋發生的海嘯，使它們不能直達香港。雖然海嘯可透過折射抵達，但它們的能量會大大減弱。因此，香港受嚴重海嘯影響的機會不大。
當地震發生並可能引發海嘯時，天文台會時刻留意太平洋海嘯警報中心(PTWC)發出的有關消息，並密切注意本港境內測潮器錄得的水位變化。如有需要，會儘快向公眾發出警告。
天文台曾經4次記錄得海嘯引發的輕微水位異常：
堪察加
智利
智利
呂宋海峽
Gravity Wave A wave in which gravity (and buoyancy, which arises from gravity) act as restoring forces to displacements from equilibrium. Examples:
from Houze's Cloud Atlas, available online courtesy of
Credit: NASA
http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html
The tsunami comprises of two waves traveling in opposite directions, with these speeds relative to the water body
where L denotes its wavelength, H the water depth, and g the gravitational acceleration.
Because it is formed by geological movements, it has very long wavelength so that L >> H, and
which depends little on its L. Therefore, different components in the tsunami, with different L, travel at nearly the same speed, so that the tsunami does not disperse even after travelling over long distances: hence its destructive power! However, as it approaches land, H decreases and so does v. The energy flux it carries being more or less the same, its height (amplitude) increases dramatically!
The
[from Wikipedia, the free encyclopedia”, posted on http://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake]
www.ucmp.berkeley.edu/geology/tectonics.html
1200 km of faultline slipped 15 m sideways, also sea bed rose by several metres
100
the day shortened by 2.68 µs (decreased oblateness of the Earth)
(tidal effects of the Moon: +15 µs per year)
GPS:
northern tip of
Credit: NASA