From: \"wcatwc list1\" <wcatwc.list1@noaa.gov> Date: June 14, 2005 8:10:58 PM PD
ID: 283958 • Letter: F
Question
From: "wcatwc list1" <wcatwc.list1@noaa.gov>
Date: June 14, 2005 8:10:58 PM PDT
Subject: TsunamiWatcherMessage
TO - TSUNAMI WARNING SYSTEM PARTICIPANTS IN
ALASKA/BRITISH COLUMBIA/WASHINGTON/OREGON/CALIFORNIA
FROM - WEST COAST AND ALASKA TSUNAMI WARNING CENTER/NOAA/NWS
SUBJECT - TSUNAMI WARNING BULLETIN - INITIAL
BULLETIN NUMBER 1
...A TSUNAMI WARNING IS IN EFFECT FOR THE COASTAL AREAS FROM THE
CALIFORNIA-MEXICO BORDER TO THE NORTH TIP OF VANCOUVER I.-BC.
...A TSUNAMI WATCH IS IN EFFECT FOR THE COASTAL AREAS FROM THE NORTH TIP OF VANCOUVER I.-BC. TO SITKA-AK...
...AT THIS TIME THIS BULLETIN IS FOR INFORMATION ONLY FOR OTHER AREAS OF
ALASKA...
EARTHQUAKE DATA
PRELIMINARY MAGNITUDE - 7.4
LOCATION - 41.3N 125.7W - 90 MILES NW OF EUREKA-CA.
300 MILES NW OF SAN FRANCISCO-CA.
TIME - 1851 ADT 06/14/2005
1951 PDT 06/14/2005
0251 UTC 06/15/2005
EVALUATION
IT IS NOT KNOWN - REPEAT NOT KNOWN - IF A TSUNAMI EXISTS BUT A
TSUNAMI MAY HAVE BEEN GENERATED. THEREFORE PERSONS IN LOW
LYING COASTAL AREAS SHOULD BE ALERT TO INSTRUCTIONS FROM THEIR
LOCAL EMERGENCY OFFICIALS. PERSONS ON THE BEACH SHOULD MOVE TO
HIGHER GROUND IF IN A WARNED AREA. TSUNAMIS MAY BE A SERIES OF WAVES WHICH COULD BE DANGEROUS FOR SEVERAL HOURS AFTER THE INITIAL WAVE ARRIVAL.
COASTAL AREAS FROM THE CALIFORNIA-MEXICO BORDER TO THE
NORTH TIP OF VANCOUVER I.-BC. INCLUSIVE.
...A TSUNAMI WARNING IS IN EFFECT FOR THE COASTAL AREAS FROM THE CALIFORNIA-MEXICO BORDER TO THE NORTH TIP OF
VANCOUVER I.-BC. INCLUSIVE...
ESTIMATED TIMES OF INITIAL WAVE ARRIVAL
CRESCENT CITY-CA 2029 PDT JUN 14 ASTORIA-OR 2154 PDT JUN 14
CHARLESTON-OR 2044 PDT JUN 14 TOFINO-BC 2157 PDT JUN 14
SAN FRANCISCO-CA 2123 PDT JUN 14 SAN PEDRO-CA 2200 PDT JUN 14
SEASIDE-OR 2126 PDT JUN 14 LA JOLLA-CA 2214 PDT JUN 14
NEAH BAY-WA 2148 PDT JUN 14
COASTAL AREAS FROM THE NORTH TIP OF VANCOUVER I.-BC. TO SITKA-AK. ...A TSUNAMI WATCH IS IN EFFECT FOR THE COASTAL AREAS FROM
THE NORTH TIP OF VANCOUVER I.-BC. TO SITKA-AK...
ESTIMATED TIMES OF INITIAL WAVE ARRIVAL
LANGARA-BC 2244 PDT JUN 14 KETCHIKAN-AK 2257 ADT JUN 14
SITKA-AK 2227 ADT JUN 14
COASTAL AREAS FROM SITKA-AK. TO ATTU-AK. TSUNAMI INFORMATION STATEMENT NO - REPEAT NO - TSUNAMI WATCH OR WARNING IS IN EFFECT FOR
THE COASTAL AREAS FROM SITKA-AK. TO ATTU-AK.
FOR INFORMATION ONLY - ESTIMATED TIMES OF INITIAL WAVE ARRIVAL
YAKUTAT-AK 2317 ADT JUN 14 CORDOVA-AK 0007 ADT JUN 15
KODIAK-AK 2332 ADT JUN 14 DUTCH HARBOR-AK 0013 ADT JUN 15
JUNEAU-AK 2334 ADT JUN 14 COLD BAY-AK 0034 ADT JUN 15
SEWARD-AK 2339 ADT JUN 14 ADAK-AK 0038 ADT JUN 15
VALDEZ-AK 2357 ADT JUN 14 HOMER-AK 0044 ADT JUN 15
SAND PT.-AK 2358 ADT JUN 14 SHEMYA-AK 0119 ADT JUN 15
THE PACIFIC TSUNAMI WARNING CENTER AT EWA BEACH HAWAII WILL ISSUE BULLETINS
FOR OTHER AREAS OF THE PACIFIC. BULLETINS WILL BE ISSUED HOURLY OR SOONER
IF CONDITIONS WARRANT. THE TSUNAMI WATCH/WARNING WILL REMAIN IN EFFECT UNTIL FURTHER NOTICE. REFER TO THE INTERNET SITE WCATWC.ARH.NOAA.GOV FOR MORE INFORMATION AND ETA SITES.
How much time was there between when the earthquake occurred and when the tsunami would have arrived in Crescent City?
How much time was there between when the warning email was issued and when the tsunami would have arrived in Crescent City? [Although this example was a false alarm, ponder for a moment the advantage of receiving a text message on your cell phone the moment a tsunami warning is issued, rather than waiting for emergency personnel to locate you where you are walking on some secluded beach.]
Explanation / Answer
Earthquakes are among the most frequently occuring and most destructive geological hazard.The significance of earthquakes lies in the shock waves produced,which may affect extensive tracts of land.The Richter scale of magnitude of earhquakes indicates the size of the earthquakes.The modified Mercalli scale is a measure of the intensity of Earthquakes.
The term Tsunami is related to earthquakes in its origin because it is caused by severe earthquakes generally of magnitude greater than 6.5 on Richter scale that occur in the ocean floors and cause vertical displacement in the oceanic crust.
The Tsunami waves rise upto heights of 20-30 m with a ferocious velocities of more than 500 km/hr washing coastal inlands upto a distance of 1.5 to 2.0 km away from the sea shore.
Since tsunamis are sub oceanic seismic events like earhquakes on the earth,these are neither preventable nor predictable.However with a great deal of research having been done in the field of seismology ,there are well defined codes of practice available to design and construct shock-resistant constructions.
The present global strategy to face risks from tsunamis is therefore focused on developing dependable warning system so that population along coastal regions can be pre-informed and evacuated well in time before the on- slaught of the ferocious tsunami waves.
Tsunami warning centre(TWC) is based on the concept that tsunamis travel travel at a much slower velocity(500-700 km/hr) than earthquake waves(6-8 km/sec).Hence if focus of an earthquake is found located instantly near or close to a coastal area in sea,some time may be available to evacuate the people upto 2-3 km away from the risk zone.
Presently a Tsunami warning system is located near Honolulu,Hawaii and provides tsunami related information to 28 international member states.The pacific ocean is considered as the risk zone for generation of tsunamis because it is surrounded by a sesmically active-belt- the circum pacific-belt where in more than 68 percent of the earthquakes have originated in the past history.
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