1
Frequency-Dependent Energy Radiation and Fault Coupling for the 2010 M8.8
2
Maule, Chile and 2011 M9.0 Tohoku, Japan Earthquakes
3
Supplementary material
4
5
6
Dun Wang and Jim Mori*
7
Disaster Prevention Research Institute, Kyoto University, Uji, Japan.
8
Correspondence should be addressed to: mori@eqh.dpri.kyoto -u.ac.jp
9
10
Contact information:
11
Dun Wang, DPRI, Kyoto University, Uji, Japan, dunwang@eqh.dpri.kyoto-u.ac.jp.
12
Jim Mori, DPRI, Kyoto University, Uji, Japan, mori@eqh.dpri.kyoto-u.ac.jp.
13
14
15
1. Effect of Stacking Window Length
16
We tested the stability of the back-projection results as a function of the length of
17
the window, using values ranging from 10 to 40 s. Figure S1 (for Maule, Chile) and
18
Figure S2 (for Tohoku, Japan) show the time progressions of the locations of the
19
maximum stack amplitude for the three frequency bands, using a series of window
20
lengths. For the results of the high and intermediate frequency bands, the locations are
21
fairly robust and do not show large differences. For the low-frequency data, the
22
locations can vary greatly, showing that they are sensitive to stacking window length,
23
especially for the windows with relatively small amplitudes. However, the locations
24
of the source corresponding to the larger amplitudes are more stable. For the Chile
25
earthquake, the sources of the large low-frequency amplitudes are located between the
26
epicenter and the areas of the high-frequency sources. For the Tohoku, Japan
27
earthquake, the sources of the large low-frequency amplitudes are located stably at
28
east and northeast of the epicenter.
29
30
2. Test of Location Resolution
31
In order to evaluate the location uncertainty from the back-projection locations for
32
the different frequency bands, we carried out our procedure on synthetic waveforms
33
formed from aftershock/foreshock recordings. The synthetic data was constructed by
34
adding recordings of large foreshocks and aftershocks. The waveforms of the
35
aftershocks were delayed to simulate the rupture velocities from the hypocenter. Two
36
rupture velocities of 2.9 km/s and 1.5 km/s for the Maule and Tohoku earthquakes,
37
respectively. The rupture velocities used are determined by Kiser and Ishii [2011] and
38
Wang and Mori [2011].
39
For the Maule earthquake source region test, we used aftershocks on March 5, 2011
40
(Mw 6.6), February 14, 2011 (Mw 6.6), and March 11, 2010 (Mw 6.9)
to form the
41
synthetic waveform. The aftershock waveforms were delayed to simulate a rupture
42
velocity of 2.9 km/s [Kiser and Ishii, 2011]. For the Tohoku earthquake we used the
43
foreshock on March 9, 2011 (Mw 7.3) and aftershock on April 7, 2011 (Mw 7.1) to
44
make the synthetic waveforms. A rupture velocity of 1.5 km/s [Wang and Mori, 2011]
45
was used to delay the waveforms.
46
As can be seen from Figure S3 and Figure S4, the back-projection results recover
47
the locations of the events used to make the synthetic waveform very well in all three
48
frequency bands for the Maule earthquake.
49
for the high-frequency data are good, but for the intermediate- and low-frequency data,
50
the locations from the back projections are about 20 to 30 km from the actual event
51
locations. The location uncertainties for the low-frequency results do not affect the
52
conclusions of this paper, since we discuss features that have location differences of
53
100 km or more.
For the Tohoku earthquake, the results
54
The uncertainties in the location will also depend on the location error of the
55
earthquake used for the empirical event. The horizontal location errors are about 20 to
56
30 km, which is consistent with the above results, which show 20 to 30 km
57
differences when using different earthquakes.
58
59
3. Using Different Events for Empirical Station Corrections
60
In order to check the possible station correction bias, we also carried out the same
61
procedure using a nearby Mw7.0 aftershock. The resultant locations of the mainshock
62
accumulated energy radiation are quite similar, indicating that the method appears
63
fairly reliable and does not depend on the choice of the smaller event (see Fig.S5 and
64
Fig.S6).
65
66
67
68
69
References:
70
Kiser, E., & Ishii, M. (2011), The 2010 Mw 8.8 Chile earthquake: Triggering on
71
multiple segments and frequency‐dependent rupture behavior. Geophys. Res.
72
Lett. 38, doi:10.1029/2011GL- 047140.
73
Wang, D. and J. Mori (2011), Rupture Process of the 2011 off the Pacific Coast of
74
Tohoku Earthquake (Mw 9.0) as Imaged with Back-Projection of Teleseismic
75
P-waves, Earth Planets Space, in press.
76
77
Figure captions:
78
Figure S1. Locations of the maximum stack amplitudes from the high- (brown),
79
intermediate- (green), and low-frequency (blue) data using window lengths of 10, 15,
80
20, 25, 30, and 40 s, for the Maule Chile earthquake. Black star shows the epicenter.
81
82
Figure S2. Locations of the maximum stack amplitudes from the high- (brown),
83
intermediate- (green), and low-frequency (blue) data using window lengths of 10, 15,
84
20, 25, 30, and 40 s, for the Tohoku, Japan earthquake. Red star shows the epicenter.
85
86
Figure S3. Locations of the maximum stack amplitudes point from back projections
87
using high- (left), intermediate- (middle), and low-frequency (right) data from
88
synthetic waveforms formed from recordings of three aftershocks for the Maule
89
earthquake. Black star show the locations of the Global CMT for the three aftershocks.
90
Open star shows the starting point (UGGS epicenter) of the Maule earthquake for
91
reference. The focal mechanisms are from the Global CMT moment tensor solutions.
92
93
Figure S4. Locations of the maximum stack amplitudes from back projections using
94
high- (left), intermediate- (middle), and low-frequency (right) data, from synthetic
95
waveforms formed from recordings of two aftershocks for the Tohoku earthquake.
96
Black stars show the locations from global CMT for the three aftershocks. Open stars
97
show the starting point (JMA epicenter) of the Tohoku earthquake for reference. The
98
focal mechanisms are from the Global CMT moment tensor solutions.
99
100
Figure S5. Cumulative radiated energies from low-pass filtered at 0.2 Hz data for the
101
March 9, 2011 M7.3 foreshock (left) and the July 10, 2011 M7.0 aftershock (right).
102
Big black stars show the mainshock epicenters, and the small ones show the
103
respective Global CMT epicenters of the two small earthquakes used to calculate the
104
station corrections for the mainshock.
105
106
Figure S6. Cumulative radiated energies from low-pass filtered at 0.2 Hz data for the
107
Tohoku M9.0 earthquake with station corrections calculated from the March 9, 2011
108
M7.3 foreshock (left) and the July 10, 2011 M7.0 aftershock (right). Large black stars
109
show the mainshock epicenters from JMA, and the small ones show the respective
110
Global CMT epicenters of the two small earthquakes used to calculate the station
111
corrections for the mainshock.
112
113
114
115
Figure S1. Locations of the maximum stack amplitudes from the high- (brown),
116
intermediate- (green), and low-frequency (blue) data using window lengths of 10, 15,
117
20, 25, 30, and 40 s, for the Maule Chile earthquake. Black star shows the epicenter.
118
119
Figure S2. Locations of the maximum stack amplitudes from the high- (brown),
120
intermediate- (green), and low-frequency (blue) data using window lengths of 10, 15,
121
20, 25, 30, and 40 s, for the Tohoku, Japan earthquake. Red star shows the epicenter.
122
123
124
125
Figure S3. Locations of the maximum stack amplitudes point from back projections
126
using high- (left), intermediate- (middle), and low-frequency (right) data from
127
synthetic waveforms formed from recordings of three aftershocks for the Maule
128
earthquake. Black star show the locations of the Global CMT for the three aftershocks.
129
Open star shows the starting point (USGS epicenter) of the Maule earthquake for
130
reference. The focal mechanisms are from the Global CMT moment tensor solutions.
131
132
133
Figure S4 Locations of the maximum stack amplitudes from back projections using
134
high- (left), intermediate- (middle), and low-frequency (right) data, from synthetic
135
waveforms formed from recordings of two aftershocks for the Tohoku earthquake.
136
Black stars show the locations from global CMT for the three aftershocks. Open stars
137
show the starting point (JMA epicenter) of the Tohoku earthquake for reference. The
138
focal mechanisms are from the Global CMT moment tensor solutions.
139
140
141
Figure S5. Cumulative radiated energies from low-pass filtered at 0.2 Hz data for the
142
March 9, 2011 Mw7.3 foreshock (left) and the July 10, 2011 Mw7.0 aftershock
143
(right). Big black stars show the mainshock epicenters, and the small ones show
144
the respective Global CMT epicenters of the two small earthquakes used to
145
calculate the station corrections for the mainshock.
146
147
148
Figure S6. Cumulative radiated energies from low-pass filtered at 0.2 Hz data for the
149
Tohoku M9.0 earthquake with station corrections calculated from the March 9,
150
2011 Mw7.3 foreshock (left) and the July 10, 2011 Mw7.0 aftershock (right).
151
Large black stars show the mainshock epicenters from JMA, and the small ones
152
show the respective Global CMT epicenters of the two small earthquakes used to
153
calculate the station corrections for the mainshock.
154
155
156
Dynamic Content Captions:
157
Animation 1: Back projection result for the M8.8 Maule, Chile earthquake using
158
159
160
161
162
USArray data high-pass filtered at 1.0 Hz.
Animation 2: Back projection result for the M9.0 Tohoku, Japan earthquake using
USArray data high-pass filtered at 1.0 Hz.