The most destructive earthquake is Japan\'s history took place near Honshu in 20

Question

The most destructive earthquake is Japan's history took place near Honshu in 2011. It was a magnitude 9 earthquakes. Some of the aftershocks were magnitude 7. How many times more energy was released by the magnitude 9 earthquakes than by the magnitude 7 aftershocks? How many times louder is a jackhammer than a washing machine if a jackhammer produces a 120 dB sound and a washing machine produces an 80 db sound? According to an article on Fireworks and Hearing Loss. "Any noise above 85 dB is considered unsafe. Most firecrackers produce sounds starting at 125 dB." Some Category 2 fireworks (sometimes called "garden fireworks") produce a sound intensity of 125 dB 0.5 meters away from the ignition site. Based on this information, what is the minimum distance friends and family should stand away from the ignition site to be at a safe hearing distance?

Explanation / Answer

Solution:(1)

It is given that

Magnitude 9 earthquake

and hence 1 whole unit of magnitude represents approximately 32 times (actually 10**1.5 times) the energy based on a long-standing empirical formula that says log(E) is proportional to 1.5M, where E is energy and M is magnitude

for magnitude 9 = (101.5)9 Energy

similerly for 7 magnitude = (101.5)7 Energy

Energy released by magnitude 9 to magnitude 7 = ((101.5)9 / (101.5)7 )

= 1000 times

Answer

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