Data Services Products: Aftershocks

Summary

Animations and figures of seismicity automatically generated following large global earthquakes (Mag > 7).

Description

Following all global earthquakes with magnitudes greater than 7, an aftershock sequence animation and figures are automatically generated and available in SPUD. The movie and figures are updated hourly for the first day and twice daily for 10 days. Colors in the plots refer to the depth in the catalog used, which is the ISC catalog for older events, the USGS PDE for recent events, and the GCMT catalog for larger events. When available, GCMT magnitudes and reference origins are the preferred source. GCMT focal mechanisms are included in plots when they become available. Results are backfilled to 1980 using the GCMT catalog as reference. Dec 2014 is the initial release of this product and future versions may have modified or new content.

For each event, there will be:

  • an aftershock sequence animation
  • a seismicity map spanning 10 days before to 10 days after the mainshock
  • a plot showing the distribution of aftershock magnitudes as time progresses
  • two plots showing distribution of aftershocks along each of the strikes given by the GCMT solution (when available)

For the figures generated, the radius of aftershocks plotted decreases as mainshock magnitude decreases:
    Mag ≥ 9.0            1000 km
    9.0 > Mag ≥ 8.5     500 km
    8.5 > Mag ≥ 8.0     400 km
    8.0 > Mag ≥ 7.0     300 km
    7.0 > Mag ≥ 6.0     200 km
            Mag < 6.0     100 km

Example animation and figures for an event

Aftershock sequence animation

Tohoku movie snapshot color

Aftershock movie example
The animations run from a day before the mainshock to 10 days after the mainshock with colors fading over the course of one day.


Tohoku aftershock map
Aftershock map showing all events from 10 days before to 10 days after the mainshock.


Background seismicity
Background seismicity is plotted for all events previous to the mainshock within 100 km depth. Larger events are plotted on top of smaller events.


Tohoku aftershock mags vs time color
Magnitude versus time are plotted from three days before to 10 days after the mainshock. GCMT focal mechanisms are used, when available.


Tohoku aftershocks vs strike 1 color
Aftershocks are plotted based on their closest point to a line given by the strike in nodal plane 1 in the GCMT solution. This is only produced if a GCMT solution is available.


Tohoku aftershocks vs strike 2 color
Aftershocks are plotted based on their closest point to a line given by the strike in nodal plane 2 in the GCMT solution. This is only produced if a GCMT solution is available.


Citations and DOIs

To cite the IRIS DMC Data Products effort:

  • Hutko, A. R., M. Bahavar, C. Trabant, R. T. Weekly, M. Van Fossen, T. Ahern (2017), Data Products at the IRIS‐DMC: Growth and Usage, Seismological Research Letters, 88, no. 3, http://doi:10.1785/0220160190.

To cite the IRIS DMC Aftershocks data product or reference use of its repository:

To cite a particular set of Aftershocks results:
    – select the Aftershocks of interest
    – click on Citations to obtain its DOI
    – insert the DOI in below reference:

  • IRIS DMC (2014), Data Services Products: Aftershocks, doi:INSERT DOI HERE.

Credits

  • Alexander Hutko

Timeline

2014-12-17
Aftershocks online

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