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10 Oct 2017 - Two M6+ events

  1. Oct 10, 2017 #1

    davenn

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    another couple of M6 events from my seismograph

    M 6.3 - 36km SSW of Putre, Chile

    M 6.7 - Bouvet Island region

    on my seismogram below,
    the P arrival for the M6.3, Chile event is approx 0652UT
    the P arrival for the M6.7, Bouvet Is event is approx 1907UT

    zhi.gif


    cheers
    Dave
     
  2. jcsd
  3. Oct 12, 2017 #2

    jedishrfu

    Staff: Mentor

    Is there any significance to these events? Is there some future event expected now that you've seen these two?
     
  4. Oct 12, 2017 #3

    davenn

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    Not particularly, they are just part of ongoing activity world wide. The avg is around 2-3 x M6-6.9 events a week
    The M 6.3 in nthrn Chile is in a very seismically active region ( the Nazca and South American plates) that sees regular M 7's and M8's.

    The M6.7 from Bouvet Is region ( southern Atlantic), tho on a plate boundary, isn't so much of an active area. Go to the west 2000km and
    you get to the South Sandwich Islands region where the activity is quite high.


    Ah hah, that's the $6 million question :wink: We never know if it's a foreshock to a much bigger event or just a stand-alone event
    There's examples of both in the seismic records

    eg ... the Japan 2011 M9 event ... it had 3 significant foreshocks
    Mar 9, M7.2 followed by 3 x M6.x events then Mar 11 the M9 shock

    i-18a4129bbe17932aeb20701709c8e8d2-Magnitudes-thumb-600x480-62555.png

    One could say ( and rightfully so) that the 3 x events were just aftershocks of the M7 main shock.
    But what makes them all foreshocks of the M9 event is their close association to the M9 both in location and in time

    The big problem is, we never know that they were foreshocks, or not, till after the fact
    As they say, "Hindsight has 20/20 vision" :wink:


    Dave
     
  5. Oct 12, 2017 #4

    jedishrfu

    Staff: Mentor

    Thanks Dave. I always like your posts on these events and your excellent explanations.
     
  6. Oct 12, 2017 #5

    davenn

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    Thankyou for the encouragement
    so few of the posts get responses, so I'm never sure how big an "interested audience" there is on the subject
    But I just keep posting anyway. :biggrin:
    Greg Bernhardt once told me "You have a unique perspective on the subject" :smile:


    Dave

    EDIT ... will reword the line above .... So few.....
     
    Last edited: Oct 13, 2017
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