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Transcript of 11 William Frank - MIT ERL William Frank.pdf · PDF file Slide5&...

  • Pinpointing  transient  aseismic  slip  at   depth  with  seismological  observations

    William  Frank NSF  Postdoctoral  Fellow,  

    Department  of  Earth,  Atmospheric,  and  Planetary  Sciences  

    In  collaboration  with  N.  Shapiro,  G.  Prieto,  M.  Campillo,  A.  Husker,  V.   Kostoglodov,  A.  Gusev,  M.  Radiguet,  B.  Rousset,  and  N.  Cotte  

    MIT  Earth  Resources  Laboratory   2016  Annual  Founding  Members  Meeting  

    May  18th,  2016

  • Pinpointing  transient  aseismic  slip  at   depth  with  seismological  observations

    William  Frank NSF  Postdoctoral  Fellow,  

    Department  of  Earth,  Atmospheric,  and  Planetary  Sciences  

    In  collaboration  with  N.  Shapiro,  G.  Prieto,  M.  Campillo,  A.  Husker,  V.   Kostoglodov,  A.  Gusev,  M.  Radiguet,  B.  Rousset,  and  N.  Cotte  

    MIT  Earth  Resources  Laboratory   2016  Annual  Founding  Members  Meeting  

    May  18th,  2016

  • Slide  2   2016  Annual  Founding  Members  Meeting

    How  is  tectonic  stress  accommodated?

    Seismic Cycle

    ‣ Updip: earthquakes (brittle) ‣ Downdip: aseismic sliding (ductile)

    Modified from Gomberg, GSAB, 2010

  • Slide  2   2016  Annual  Founding  Members  Meeting

    How  is  tectonic  stress  accommodated?

    Seismic Cycle

    ‣ Updip: earthquakes (brittle) ‣ Downdip: aseismic sliding (ductile)

    What happens in between in the frictional transition zone?

    Modified from Gomberg, GSAB, 2010

    Transition zone

  • Slide  3   2016  Annual  Founding  Members  Meeting

    What  do  we  know  about  the  transition  zone?

    ‣ High pore fluid pressure → low effective stress

    ‣ Industrial context: Parallels with microseismicity?

    ‣ Partitioning of deformation between seismic and aseismic

    ‣ Industrial context: How does (a)seismic slip in HF regions occur? Can we track it?

    Modified from Gomberg, GSAB, 2010

    Transition zone

  • Slide  4   2016  Annual  Founding  Members  Meeting

    Seismic  vs.  aseismic  deformation  in  the  transition  zone

    Seismic Aseismic

    Name  (jargon) Low-­‐frequency  earthquake Slow  slip  event

    Duration Seconds Days  to  years

    Recurrence  time Seconds Weeks  to  years

    Rupture  length ~100  meters  (?) >100  kilometers

    Slip Microns  (?) Centimeters

    Moment  magnitude -­‐1  to  1 5.5  to  7.5

    Instrument Seismometer GPS/tiltmeter/strainmeter

  • Slide  4   2016  Annual  Founding  Members  Meeting

    Seismic  vs.  aseismic  deformation  in  the  transition  zone

    Seismic Aseismic

    Name  (jargon) Low-­‐frequency  earthquake Slow  slip  event

    Duration Seconds Days  to  years

    Recurrence  time Seconds Weeks  to  years

    Rupture  length ~100  meters  (?) >100  kilometers

    Slip Microns  (?) Centimeters

    Moment  magnitude -­‐1  to  1 5.5  to  7.5

    Instrument Seismometer GPS/tiltmeter/strainmeter

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Repeating  seismicity  in  the  transition  zone

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

    Repeating  seismicity  in  the  transition  zone

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

    Repeating  seismicity  in  the  transition  zone

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

    Repeating  seismicity  in  the  transition  zone

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

    Repeating  seismicity  in  the  transition  zone

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

    Repeating  seismicity  in  the  transition  zone

  • Slide  5   2016  Annual  Founding  Members  Meeting

    Transition zone

    Modified from Gomberg, GSAB, 2010

    4 hours

    Repeating  seismicity  in  the  transition  zone

  • Slide  6   2016  Annual  Founding  Members  Meeting

    Example  waveforms  for  repeating  seismic  event

    PLAT HHN XALI HHN TONA HHN SATA HHN ZACA HHN

    No rm

    al ize

    d G

    ro un

    d Ve

    lo cit

    y

    TOMA HHN CIEN HHN BUCU HHN CASA HHN

    7050 7055 7060 7065 7070 7075 7080 7085 AMAC HHN

    Time (s)

    O ce

    an ic

    sl ab

    Sl ow

    sl ip

    Re pe

    at in

    g se

    ism ic

    ity

    Co nt

    in en

    ta l

    cr us

    t

  • Slide  7   2016  Annual  Founding  Members  Meeting

    Detecting  other  events  from  the  same  seismic  source

    PLAT HHN XALI HHN TONA HHN SATA HHN ZACA HHN

    No rm

    al ize

    d G

    ro un

    d Ve

    lo cit

    y

    TOMA HHN CIEN HHN BUCU HHN CASA HHN

    7050 7055 7060 7065 7070 7075 7080 7085 AMAC HHN

    Time (s)

    Waveform matching search:

    ‣ Template event consists of:

    ‣ Network waveforms

    ‣ Network moveout

  • Slide  7   2016  Annual  Founding  Members  Meeting

    Detecting  other  events  from  the  same  seismic  source

    PLAT HHN XALI HHN TONA HHN SATA HHN ZACA HHN

    No rm

    al ize

    d G

    ro un

    d Ve

    lo cit

    y

    TOMA HHN CIEN HHN BUCU HHN CASA HHN

    7050 7055 7060 7065 7070 7075 7080 7085 AMAC HHN

    Time (s)

    Waveform matching search:

    ‣ Template event consists of:

    ‣ Network waveforms

    ‣ Network moveout

  • Slide  8   2016  Annual  Founding  Members  Meeting

    Events detected with waveform matching: different events, same source

    Visualizing  cataloged  seismicity

  • Slide  8   2016  Annual  Founding  Members  Meeting

    Visualizing  cataloged  seismicity

    Events detected with waveform matching: different events, same source

  • Slide  9   2016  Annual  Founding  Members  Meeting

    Repeating  earthquakes  in  the  Mexican  subduction  zone

    Modified from Frank et al., JGR, 2014

    O ce

    an ic

    sl ab

    Sl ow

    sl ip

    Re pe

    at in

    g se

    ism ic

    ity

    Co nt

    in en

    ta l

    cr us

    t

  • Slide  10   2016  Annual  Founding  Members  Meeting

    What  does  a  GPS  “see”  on  the  surface?

    Modified from Frank et al., JGR, 2014

    O ce

    an ic

    sl ab

    Sl ow

    sl ip

    Re pe

    at in

    g se

    ism ic

    ity

    Co nt

    in en

    ta l

    cr us

    t

  • Slide  11   2016  Annual  Founding  Members  Meeting

    Aseismic  slip  accompanied  by  episodic  seismicity

    Modified from Frank et al., JGR, 2014

    O ce

    an ic

    sl ab

    Sl ow

    sl ip

    Re pe

    at in

    g se

    ism ic

    ity

    Co nt

    in en

    ta l

    cr us

    t

    Loading

    Release

    Jan ‘05 Jan ‘06 Jan ‘07

  • Slide  12   2016  Annual  Founding  Members  Meeting

    Aseismic  signature  of  a  Mw  7.5  slow  slip  event

    Loading

    Release

    Jan ‘05 Jan ‘06 Jan ‘07 Modified from Kostoglodov et al., GRL, 2010

    Does slow slip occur at other times?

    ‣ Not obvious on GPS position time series…

  • Slide  13   2016  Annual  Founding  Members  Meeting

    Characteristic  episodic  seismicity  during  slow  slip?

    Modified from Frank et al., JGR, 2014

    O ce

    an ic

    sl ab

    Sl ow

    sl ip

    Re pe

    at in

    g se

    ism ic

    ity

    Co nt

    in en