[Geophysical Research Letters]
Supporting Information for
[Temporal Variation in the Magnitude-Frequency Distribution during the GuyGreenbrier Earthquake Sequence]
[Yihe Huang, Gregory C. Beroza]
[Stanford Center for Induced and Triggered Seismicity, 397 Panama Mall, Stanford, CA 94305]
Contents of this file
Table S1
Figures S1 to S9
Introduction
The supporting information includes one table and eight figures:
Table S1 compares the number of catalog events and detections from our single-station
template matching. The magnitude of completeness for each month is also shown in the
table.
Figure S1 shows the distribution of cross-correlation coefficients for an hour of seismic
data given a certain template. Figure S2 compares the WHAR velocity seismograms and
the corresponding Wood-Anderson seismograms for five earthquakes in October 2010.
The benchmark between the WHAR magnitudes and the Wood-Anderson magnitudes of
earthquakes in October 2010 and February 2011 are shown in Figure S3.
Figure S4 shows the monthly injection moments, volumes and pressures of well #1 and
#5, and the seismicity rate between July 2010 and October 2011.
Figure S5 demonstrates how the magnitude of completeness is determined from the
smallest misfit between the observed and synthetic MFD. Figure S6 compares the
maximum-likelihood and robust-fit estimates of b-values, and Figure S7 compares the
maximum-likelihood estimates of b-values given different distributions. Figure S8 shows
the maximum-likelihood estimates of truncated magnitudes given different distributions.
Figure S9 compares the cumulative moment release to the upper bound of seismic
moment predicted by monthly injection volume.
Month
Catalog events
Detections
Mc
July 2010
August 2010
September 2010
October 2010
November 2010
December 2010
January 2011
February 2011
March 2011
April 2011
May 2011
June 2011
July 2011
August 2011
September 2011
October 2011
15
24
27
222
209
151
60
214
209
115
27
6
29
3
3
63
16,528
10,432
15,671
122,693
97,264
52,767
14,348
39,100
53,563
11,793
5,459
4,776
3,896
3,442
3,610
7,463
-1.0
-1.1
-1.1
-0.3
-0.2
-1.0
-1.2
-0.2
-0.5
-0.5
-1.1
-1.0
-1.3
-1.3
-1.2
-0.7
Table S1. Numbers of ANSS catalog events, detections and the magnitude of
completeness (Mc) in this study for each month.
Figure S1. The distribution of cross-correlation coefficients calculated from crosscorrelating a template with an hour of continuous seismic data. Inset shows the windows
with cross-correlation coefficients larger than 8 times the median absolute deviation.
Figure S2. Velocity seismograms of different earthquakes recorded at WHAR (left) and
the corresponding Wood-Anderson seismograms (right). The earthquake magnitudes
determined from peak velocity and the Wood-Anderson peak displacement are shown
on the top of each seismogram. Although crustal corrections would be different than in
southern California where the local magnitude was defined, the short propagation
distance (<10 km) for events in this sequence means that the distance correction has
little influence.
Figure S3. The benchmark between our magnitudes and the Wood-Anderson
magnitudes of earthquakes in October 2010 (blue) and February (2011). The dashed
lines denote the robust-fit relations for each month.
Figure S4. Top: Monthly injection moments (the product of injection volume and
injection pressure) of two nearby injection wells and 10 times the number of earthquakes
with magnitudes larger than -1 in each month. Bottom: Monthly injection volumes and
injection pressures of two wells.
Figure S5. The misfit between the observed and synthetic MFD as a function of
magnitude of completeness for August 2010. The lowest misfit indicates that Mc is ~ 1.1.
Figure S6. The maximum-likelihood and robust-fit estimates of b-values for each interval
of 10,000 earthquakes.
Figure S7. The maximum-likelihood estimates of b-values for every 10,000 earthquakes
under assumptions of different distributions.
Figure S8. Estimates of truncated magnitudes for every 10,000 earthquakes under
assumptions of different distributions.
Figure S9. Cumulative moment release as a function of time vs. the upper bound of
seismic moment calculated by the product of the shear modulus (30 MPa) and the
monthly injection volume, Equation (13) in McGarr [2014].