Data Services Newsletter

Volume 22 : No 3 : Winter 2020

Aftershocks data product: What’s new?

The aftershocks data product was upgraded on August 1, 2020 to enhance and expand its collection of plots and animations. Since 2014, Aftershocks movies and plots have been generated for every global earthquake with magnitude 7 and greater (backfilled to 1980) and are updated hourly for 10 days after the event time.

The new Aftershocks data products (starting with August 2020 events) are generated using events from the FDSN (USGS) event service and the GCMT catalog and includes:

  • customized links to FDSN event services and IRIS earthquake browser under the Attachments pane (Table 1)
  • an aftershock sequence animation
  • an aftershock sequence heatmap animation, when available (Figure 1)
  • a background seismicity plotted for all events previous to the mainshock
  • a seismicity map spanning 3 days before to 10 days after the mainshock (Figure 2)
  • a seismicity heatmap spanning 3 days before to 10 days after the mainshock, when available (Figure 3)
  • a plot depicting distribution of aftershock magnitudes as time progresses that also includes an hourly event rate bar chart as shown in Figure 4
  • two plots showing distribution of aftershocks along each of the strikes given by the GCMT solution (when available)
  • two plots showing distribution of aftershocks with depth along each of the strikes given by the GCMT solution, when available

Product overview:
ds.iris.edu/ds/products/aftershocks

Aftershocks in SPUD:
ds.iris.edu/spud/aftershock

Aftershocks data product DOI:
https://doi.org/10.17611/dp/as.1



Table 1. Customized links for M7.8 ALASKA PENINSULA 2020-07-22 06:12:44 UTC Lat: 55.03° Lon: -158.52° depth: 28.0 km

IRIS Earthquake Browser URL (M ≥ 3.1 from 2020-07-19 to 2020-07-31))
IRIS Earthquake Browser URL (M ≥ 3.1)
FDSN Event Service URL (M ≥ 3.1 from 2020-07-19 to 2020-07-31)
FDSN Event Service URL (GCMT catalog, M ≥ 3.1 from 2020-07-19 to 2020-07-31)


Heatmap animation
Figure 1. Heatmap animation run for the M7.8 Alaska Peninsula earthquake of July 22, 2020. Animation starts a day before the mainshock and ends 10 days after the mainshock. Click on image to play the animation.

Seismicity map
Figure 2. A seismicity map for the M7.8 Alaska Peninsula earthquake area spanning 3 days before to 10 days after the mainshock of July 22, 2020. Click on image for a larger view.

Heatmap plot
Figure 3. Heatmap plot for the M7.8 Alaska Peninsula earthquake of July 22, 2020 from three days before the mainshock to 10 days after the mainshock. Click on image for a larger view.

Distribution of aftershock magnitudes
Figure 4. A plot showing the distribution of aftershock magnitudes for the July 22, 2020 M7.8 Alaska Peninsula earthquake as time progresses. Plot covers three days before the mainshock to 10 days after the mainshock of July 22, 2020. The blue bar chart above the plot shows the hourly rate of event occurrence. Click on image for a larger view.

by Data Products (IRIS DMC)

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