How could someone predict the approximate location of an epicenter without a seismograph?
Aug 21, 2009
in
Earthquake Questions
How could someone predict the approximate location of an epicenter without a seismograph??
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3 comments
Michele on August 21, 2009 at 4:28 am
Well, you can use a map and draw three circles using a compass and wherever they intersect is where the epicenter is. You draw the 3 circles by knowing the difference in arrival times of the P and S-waves (the seismic waves produced by earthquakes).
The greater the difference in arrival times, the farther that location is from the epicenter.
In New York State, students have to do that on the Earth Science Regents exam. This is the graph they use.
http://www.regentsprep.org/Regents/earthsci/units/earthquakes/earthquakewavetraveltime.gif
A.Ganapathy India on August 21, 2009 at 4:28 am
Dear fried , I am the one issued the warning 2 hours before Tsunami struck our coast. I am doing research on early warning systems for earthquakes from the year 2001.Because our country lost the life of 100,000 people due to earthquake in the place called Buji.I have sucess fully designed the fallowing instruments which are functioning well in my research center at my house. Some of the instruments are 1. Earthquake alarm senses all types of seismic waves,
2. Distance finder. It gives direct measure of distance of epicenter .The concept of this instrument is it starts at the arrival of p wave and shows one K/M distance for every lapse of 125 m/seconds.It stops at the time of arrival time of S wave. Therefore the difference in the arrival time multiplied ( the difference in speed ) gives the distance.
3.The direction finder which I have designed is nothing but the electronic version of ancient Chinese direction finder will give you the direction of epicenter. When you know the direction and distance you can mark the epicenter.Of course it is approximate.But it is sufficient to suspect that whether the epicenter could be in sea or in land. I was able to judge the magnitude on the boxing day Tsunami because my earthquake alarm sensed the seismic wave for an ununbelievable time of 12 minutes 2 hours before Tsunami struck our coast.
Clay C on August 21, 2009 at 4:28 am
Survey the destruction and see where it is most intense. That is the surface location over the epicenter.