环境地质学
Environmental Geology
主讲人,万新南 教授
Prof,Wan xinnan
地球内部过程
Tsunamis海啸 and Coastal Flooding
地球内部过程
Tsunamis海啸 and Coastal Flooding
Coastal areas,especially around
the Pacific Ocean basin where so
many large earthquakes occur,
may also be vulnerable易于 to
tsunamis,
地球内部过程
Tsunamis海啸 and Coastal Flooding
These are seismic sea waves,sometimes improperly called,tidal
waves,” although they have nothing to do with tides,When an
undersea or near-shore earthquake occurs,sudden movement of
the sea floor may set up waves traveling away from that spot,like
ripples in a pond caused by a dropped pebble,Contrary to modern
movie fiction,tsunamis are not seen as huge breakers in the open
ocean that topple ocean liners in one sweep,In the open sea,the
tsunamis are only unusually broad swells on the water surface,
地球内部过程
Tsunamis海啸 and Coastal Flooding
As tsunamis approach land,however,they develop into large
breaking waves,as the undulating起伏 waters,touch bottom”near
shore,these breakers can easily be over 15 meters high in the case
of larger earthquakes,Several such breakers may crash over the
coast in succession相继 ; between waves,the water may be pulled
swiftly seaward,emptying a harbor海港 or bay,and perhaps pulling
unwary粗心 onlookers旁观者 along,
地球内部过程
Tsunamis海啸 and Coastal Flooding
Tsunamis can travel very quickly－ speeds of 1,000 kilometers/hour
(600 miles/hour) are not uncommon－ and tsunamis set off on one
side of the Pacific may still cause noticeable effects on the other
side of the ocean,A tsunami set off by a 1960 earthquake in Chile
was still vigorous enough to cause 7-meter-high breakers when it
reached Hawaii some fifteen hours later,and twenty-five hours after
the earthquake,the tsunami was detected in Japan,
地球内部过程
Tsunamis海啸 and Coastal Flooding
Given the speeds at which tsunamis travel,little can be done to
warn those near the earthquake epicenter,but people living some
distance away can be warned in time to evacuate疏散,saving lives,
if not property,
地球内部过程
Tsunamis海啸 and Coastal Flooding
In 1948,two years after a devastating tsunami hit Hawaii,the U.S,
Coast and Geodetic测量 Survey established a Tsunami Early
Warning System,based in Hawaii,Whenever a major earthquake
occurs in the Pacific region,sea-level data are collected from a
series of monitoring stations around the Pacific,
地球内部过程
Tsunamis海啸 and Coastal Flooding
If a tsunami is detected,data on its source,speed,and estimated
time of arrival can be relayed传送 to areas in danger and people can
be evacuated as necessary,The system does not,admittedly诚然,
always work perfectly,
地球内部过程
Tsunamis海啸 and Coastal Flooding
In the 1964 Alaskan earthquake,disrupted中断 communications
prevented warnings from reaching some areas quickly enough,Also,
residents' responses to the warnings were variable; Some ignored
the warnings,and some even went closer to shore to watch the
waves,often with tragic consequences,Two tsunami warnings were
issued in early 1986 following earthquakes in the Aleutians阿留申群
岛, They were largely disregarded忽视, Fortunately,in that instance,
the feared tsunamis did not materialize.
地球内部过程
Tsunamis海啸 and Coastal Flooding
Even in the absence of tsunamis,there is the possibility of coastal
flooding from sudden subsidence as plates shift during an
earthquake,Areas that were formerly dry land may be permanently
submerged and become uninhabitable,Conversely,uplift of sea floor
may make docks码头 and other coastal structures useless,
Environmental Geology
主讲人,万新南 教授
Prof,Wan xinnan
地球内部过程
Tsunamis海啸 and Coastal Flooding
地球内部过程
Tsunamis海啸 and Coastal Flooding
Coastal areas,especially around
the Pacific Ocean basin where so
many large earthquakes occur,
may also be vulnerable易于 to
tsunamis,
地球内部过程
Tsunamis海啸 and Coastal Flooding
These are seismic sea waves,sometimes improperly called,tidal
waves,” although they have nothing to do with tides,When an
undersea or near-shore earthquake occurs,sudden movement of
the sea floor may set up waves traveling away from that spot,like
ripples in a pond caused by a dropped pebble,Contrary to modern
movie fiction,tsunamis are not seen as huge breakers in the open
ocean that topple ocean liners in one sweep,In the open sea,the
tsunamis are only unusually broad swells on the water surface,
地球内部过程
Tsunamis海啸 and Coastal Flooding
As tsunamis approach land,however,they develop into large
breaking waves,as the undulating起伏 waters,touch bottom”near
shore,these breakers can easily be over 15 meters high in the case
of larger earthquakes,Several such breakers may crash over the
coast in succession相继 ; between waves,the water may be pulled
swiftly seaward,emptying a harbor海港 or bay,and perhaps pulling
unwary粗心 onlookers旁观者 along,
地球内部过程
Tsunamis海啸 and Coastal Flooding
Tsunamis can travel very quickly－ speeds of 1,000 kilometers/hour
(600 miles/hour) are not uncommon－ and tsunamis set off on one
side of the Pacific may still cause noticeable effects on the other
side of the ocean,A tsunami set off by a 1960 earthquake in Chile
was still vigorous enough to cause 7-meter-high breakers when it
reached Hawaii some fifteen hours later,and twenty-five hours after
the earthquake,the tsunami was detected in Japan,
地球内部过程
Tsunamis海啸 and Coastal Flooding
Given the speeds at which tsunamis travel,little can be done to
warn those near the earthquake epicenter,but people living some
distance away can be warned in time to evacuate疏散,saving lives,
if not property,
地球内部过程
Tsunamis海啸 and Coastal Flooding
In 1948,two years after a devastating tsunami hit Hawaii,the U.S,
Coast and Geodetic测量 Survey established a Tsunami Early
Warning System,based in Hawaii,Whenever a major earthquake
occurs in the Pacific region,sea-level data are collected from a
series of monitoring stations around the Pacific,
地球内部过程
Tsunamis海啸 and Coastal Flooding
If a tsunami is detected,data on its source,speed,and estimated
time of arrival can be relayed传送 to areas in danger and people can
be evacuated as necessary,The system does not,admittedly诚然,
always work perfectly,
地球内部过程
Tsunamis海啸 and Coastal Flooding
In the 1964 Alaskan earthquake,disrupted中断 communications
prevented warnings from reaching some areas quickly enough,Also,
residents' responses to the warnings were variable; Some ignored
the warnings,and some even went closer to shore to watch the
waves,often with tragic consequences,Two tsunami warnings were
issued in early 1986 following earthquakes in the Aleutians阿留申群
岛, They were largely disregarded忽视, Fortunately,in that instance,
the feared tsunamis did not materialize.
地球内部过程
Tsunamis海啸 and Coastal Flooding
Even in the absence of tsunamis,there is the possibility of coastal
flooding from sudden subsidence as plates shift during an
earthquake,Areas that were formerly dry land may be permanently
submerged and become uninhabitable,Conversely,uplift of sea floor
may make docks码头 and other coastal structures useless,
