Math - Working with Logs!!

posted by .

On September 26 2001, an earthquake in North Bay measured 5.0 on the Ritcher scale. What is the magnitude of an earthquake 3 times as intense as North Bay's earthquake?


I would post my answer, but in text, it's just confusing and I can't post picture links to show my work...


Btw, the answer is 5.477

  • Math - Working with Logs!! -

    In 1935 C.F. Richter set up the scale of earthquakes by
    R = log(I) where R is the Richter scale number and I is the intensity of the earthquake

    so from your data
    5 = log(I)
    I = 10^5

    so an earthquake 3 times as intense would be 3I
    so multiplying the above equation by 3
    3I = 3(10^5)
    log (3I) = log(3*10^5)
    = log 3 + log 10^5
    = .47712 + 5
    = 5.47712

  • Math - Working with Logs!! -

    So, you don't use the equation:

    M = log(I_i / I_o) ?

  • Math - Working with Logs!! -

    most texts, and the one that I used last, use the formula

    R = log(I/I0) where 0 is a constant, the minimum intensity corresponding to R = 0

    so if you want

    5 = log (I/I0)
    5^10 = I/I0
    3*5^10 = 3I/I0
    log(3*5^10 = log(I/I0)

    notice it has no effect on the answer

  • Math - Working with Logs!! -

    i don't get where the 3 goes in the second line of this part :

    log (3I) = log(3*10^5)
    = log 3 + log 10^5

  • Math - Working with Logs!! -

    You have it right in the second line in the laws of logarithms a*b ends up equaling log 3 + log 10^5

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Word problem 2

    The 1985 Mexico city earthquake had a magnitude of 8.1 on the Richter scale. The 1976 earthquake in Tangshan, China was 1.26 times and intense. What was the magnitude of the Tangshan earthquake. Thanks
  2. math

    What is the magnitude on the Richter Scale of an earthquake measuring 3.7 x 10^5 i(sub 0)?
  3. math30

    The 1933 earthquake in Japan registered 8.9 on the Richter scale. a.The 1985 earthquake in Peru registered 7.7 on the Richter scale. How many more times intense was the earthquake in Japan?
  4. Math

    In 1986 an earthquake measuring 5.0 on the Richter scale hit northeast Ohio. This earthquake is _______ times as intense as a magnitude 2.0 quake
  5. algebra2

    the April 2015 earthquake in Nepal measured 7.8 in magnitude.in 1988 there was an earthquake in the same area that measured 6.3 on the richter scale. how many times greater was the most recent earthquake than the one in 1988?
  6. College Algebra

    This exercise deals with logarithmic scales. Earthquake A had a magnitude of 8.2 on the Richter scale. At the same time an earthquake B with magnitude 4.8 caused only minor damage. How many times more intense was earthquake A than …
  7. Math

    Logrithmetic Problem question Last week there was an earthquake that measured as a magnitude of 3.2 on the Richter scale. Today you hear on the radio that there was a second earthquake that was 27 times more intense than the first. …
  8. Math

    Im wondering for this question if I'm right and going toward the right direction. Last week there was an earthquake that measured as a magnitude of 3.2 on the Richter scale. Today you hear on the radio that there was a second earthquake …
  9. Math Exponetial Function Problem Question?

    Im confused if im doing this right Last week there was an earthquake that measured as a magnitude of 3.2 on the Richter scale. Today you hear on the radio that there was a second earthquake that was 27 times more intense than the first. …
  10. math help plz really urgent

    1. The formula M=log I/S determines the magnitude of an earthquake, where I is the intensity of the earthquake and S is the intensity of a “standard earthquake.” How many times stronger is an earthquake with a magnitude of 8 than …

More Similar Questions