Earthquake source parameters for the January, 2010, Haiti mainshock and
aftershock sequence
Meredith Nettles1,2 and Vala Hjörleifsdóttir1,3
1
2
Lamont-Doherty Earth Observatory of Columbia University
Department of Earth and Environmental Sciences, Columbia University
3
Now at Universidad Nacional Autónoma de México
submitted to GJI May 27, 2010
Accepted —- ; Received —- ; in original form 2010 May 27
Abbreviated title: Haiti earthquake source parameters
Corresponding author:
Meredith Nettles
tel: +1 845 365 8613
fax: +1 845 365 8150
email: [email protected]
1
Summary
2
Previous analyses of geologic and geodetic data suggest that the obliquely compressive relative mo-
3
tion across the Caribbean–North America plate boundary in Hispaniola is accommodated through
4
strain partitioning between near-vertical transcurrent faults on land and low-angle thrust faults
5
offshore. In the Dominican Republic, earthquake focal-mechanism geometries generally support
6
this interpretation. Little information has been available about patterns of seismic strain release
7
in Haiti, however, due to the small numbers of moderate-to-large earthquakes occurring in west-
8
ern Hispaniola during the modern instrumental era. Here, we analyze the damaging MW =7.0
9
earthquake that occurred near Port au Prince on January 12, 2010, and aftershocks occurring in
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the four months following this event, to obtain centroid–moment-tensor (CMT) solutions for 50
11
earthquakes with magnitudes as small as MW =4.0. While the January 2010 mainshock exhibited
12
primarily strike-slip motion on a steeply dipping nodal plane (strike=250◦ , dip=71◦ , rake=22◦ ), we
13
find that nearly all of the aftershocks show reverse-faulting motion, typically on high-angle (30◦ –
14
45◦ ) nodal planes. Two small aftershocks (MW 4.2 and 4.6), located very close to the mainshock
15
epicenter, show strike-slip faulting with geometries similar to the mainshock. One aftershock lo-
16
cated off the south coast of Haiti shows low-angle thrust faulting. We also analyze earthquakes
17
occurring in this region from 1977–2009 and find evidence for both strike-slip and reverse fault-
18
ing. The pattern of seismic strain release in southern Haiti thus indicates that partitioning of plate
19
motion between transcurrent and reverse structures extends far west within Hispaniola. While we
20
see limited evidence for low-angle underthrusting offshore, most reverse motion appears to oc-
21
cur on high-angle fault structures adjacent to the Enriquillo fault. Our results highlight the need
22
to incorporate seismogenic slip on compressional structures into hazard assessments for southern
23
Haiti.
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Keywords: Earthquake source observations; Seismicity and tectonics; Caribbean tectonics
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1
Introduction
26
A large and destructive earthquake of MW 7.0 occurred on January 12, 2010, near the densely
27
populated capital city of Haiti, Port au Prince. The earthquake occurred in a region of known, but
28
poorly characterized, historical seismicity (e.g., Scherer, 1912), on the Enriquillo–Plaintain Garden
29
fault system. This system accommodates primarily transform motion between the Caribbean and
30
North American plates (e.g., Mann et al., 1995). The overall relative plate motion is transpressional
31
(e.g., Sykes et al., 1982; Deng & Sykes, 1995; Dixon et al., 1998; DeMets et al., 2000; Manaker et
32
al., 2008), and many compressional geological features have been mapped in the region (Mann et
33
al., 1995). However, the only mapped throughgoing fault structure near the source of the January
34
12 earthquake, the Enriquillo fault, exhibits primarily transcurrent motion, and is believed to dip
35
nearly vertically (Mann et al., 1995, 2002).
36
No earthquakes larger than M∼5 have occurred in southern Haiti during the last 34 years,
37
approximately the era of modern instrumental recording and the timespan (1976–2009) covered
38
by the Global Centroid–Moment Tensor (GCMT) catalog (Ekström et al., 2005; Dziewonski et
39
al., 1981). One earthquake in northern Haiti, on March 2, 1994, of MW 5.4, exhibits left-lateral
40
strike-slip motion on a nodal plane striking east-southeast, consistent with the mapped geometry
41
of the Septentrional fault associated with the northern part of the plate-boundary zone (Prentice et
42
al., 1993; Mann et al., 1998). The most recent large earthquake on the island of Hispaniola, prior
43
to the January 12, 2010, event, occurred on September 22, 2003, in the Dominican Republic, with
44
moment magnitude MW 6.4. The focal mechanism for that event, as for all other earthquakes of
45
MW 6.0 or larger occurring in the Dominican Republic and included in the GCMT catalog, shows
46
thrust faulting.
47
Paleoseismic investigations and historical reports make it clear that large earthquakes have
48
occurred in Haiti previously (e.g., Scherer, 1912; Prentice et al., 1993). Recent studies using ge-
49
ological and geodetic data have also highlighted the potential for earthquakes of M∼7–7.5 on the
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Enriquillo and Septentrional faults (Calais et al., 2002; Manaker et al., 2008). Little is known,
51
however, about the character of smaller, recent earthquakes in the Enriquillo fault region, or about
2
52
background seismicity rates, because of the absence of a local seismic network in Haiti. Follow-
53
ing the great 2004 Sumatra–Andaman earthquake and the large tsunami it generated, the United
54
States Geological Survey (USGS) invested in a significant improvement to broadband seismolog-
55
ical observing capabilities in the Caribbean, installing nine broadband seismometers in the region
56
(network code CU), each with near-realtime telemetry capabilities. The combined network cover-
57
age provided by the CU and global-network stations, along with improvements to moment-tensor
58
determination techniques (Arvidsson & Ekström, 1998; Ekström et al., 1998) now make analysis
59
of smaller earthquakes possible.
60
Knowledge of seismic strain-release patterns prior to and following the January 2010 main-
61
shock is important for understanding how strain is accommodated throughout the region, and for
62
understanding possible effects of static stress changes related to the mainshock and larger after-
63
shocks. The minimum magnitude threshold for global CMT analysis is normally set at M∼5,
64
which would lead to GCMT analyses of fewer than a dozen events for the current Haiti se-
65
quence. Here, we present centroid–moment-tensor solutions for 50 earthquakes of the 2010 Haiti
66
mainshock–aftershock sequence, including events with magnitudes as small as MW =4.0. We also
67
present analyses of four earthquakes of magnitude 4.3–4.9 occurring prior to the mainshock, during
68
the years 1990–2008.
69
2
70
We apply the centroid–moment-tensor approach (Dziewonski et al., 1981; Dziewonski & Wood-
71
house, 1983; Ekström et al., 2005) to obtain moment tensors, centroid locations and centroid times
72
for the January 12, 2010, Haiti mainshock and aftershock sequence. We attempt to analyze all
73
earthquakes in the map region shown in Figure 1 reported by the USGS National Earthquake In-
74
formation Center (NEIC) as of May 20, 2010, with preliminary magnitudes of 4.0 and larger for
75
the four months following the mainshock (2010/01/12–2010/05/12). In addition, we attempt to
76
analyze all events reported in the USGS monthly listing with magnitude 4.0 or larger during the
Data and methods
3
77
period 1977–2009.
78
For larger events (approximately MW ≥5.0), we follow the standard procedures used for global
79
CMT analysis (Ekström et al., 2005). These analyses incorporate long-period body waves in the
80
period range 50–150 s; mantle waves in the period range 125–350 s; and intermediate-period sur-
81
face waves in the period range 50–150 s. The determination of source parameters for smaller
82
events relies primarily on the intermediate-period surface waves; the surface-wave analysis is im-
83
plemented as described by Arvidsson & Ekström (1998) and Ekström et al. (1998). For some
84
events, we adjust the filter towards shorter periods, which typically provide better signal-to-noise
85
ratios for shallow earthquakes. Most such events are analyzed in the 40–100 s band. For the small-
86
est events, typically those of MW ≤ 4.5, the closest stations (∆ ≤ 15◦ ) are analyzed in the period
87
range 35–75 s. The filter is selected on a station-by-station basis in this case. We use data recorded
88
at the stations of the GSN, Geoscope, Geofon, the Lamont-Doherty Cooperative Seismographic
89
Network (LCSN), and the USGS Caribbean network (CU) for our analyses, as well as stations of
90
the Abbreviated Seismic Research Observatory (ASRO) network for early events.
91
3
92
We are able to obtain CMT solutions for 50 earthquakes of the January 12, 2010, sequence, and
93
four events occurring prior to 2010. Focal mechanisms for these events are shown in Figure 1
94
and source parameters are presented in Supplementary Table 1. The source parameters can also
95
be downloaded in electronic format from our website (www.globalcmt.org). In the figures
96
and table, we identify 14 of the events as having less-well constrained focal mechanisms. These
97
are events with fewer usable data records, either due to small event size or the presence of large
98
amplitude waveforms from earlier events. As can be seen in Figure 1, the results for these events
99
are consistent with those for the best-constrained events.
Analysis and Results
4
100
3.1
The January 12, 2010, mainshock
101
The source parameters obtained for the mainshock are similar to those for the quick CMT dis-
102
tributed within hours of the event. The refined solution has scalar moment M0 = 4.4 × 1026 dyne-
103
cm (MW =7.0). The presumed fault plane strikes 250◦ and dips 71◦ north-northwest. The slip
104
angle of 22◦ indicates primarily left-lateral motion, with a moderate thrust component. The best-
105
fitting moment tensor includes a non-double-couple component that is relatively large, with the
106
intermediate eigenvalue ∼20% the size of the absolutely largest eigenvalue. The size of the non-
107
double-couple component is not well constrained, but is also consistent with a thrust contribution
108
to the mainshock. The geometry of the focal mechanism obtained when the solution is required
109
to represent a perfect double couple is very similar to the double-couple part of the unconstrained
110
solution, with strike 252◦ , dip 66◦ , and rake 28◦ .
111
The mainshock focal mechanism, which corresponds to the best point-source representation
112
of the earthquake geometry, is consistent with oblique slip on a single fault plane or, if the non-
113
double-couple component represents a source feature, nearly simultaneous slip on two separate
114
fault planes experiencing left-lateral and reverse slip. To assess seismological constraints on the
115
geometry of the mainshock fault or faults, we perform two analyses.
116
First, we invert the waveforms used to determine the mainshock moment tensor for a CMT
117
solution composed of two subsources to determine the geometry of the reverse mechanism that,
118
paired with a near-vertical strike-slip fault, best explains the observed waveforms. One subsource is
119
constrained to have a nodal plane oriented 250◦ with pure left-lateral slip and a dip of either 71◦ or
120
90◦ , while the geometry of the second subsource is constrained to be a double couple, but otherwise
121
left free. The retrieved geometry of the second subsource depends somewhat on the subsource time
122
separation, but we find that a reverse-faulting subsource with a strike of ∼ 250–270◦ , dip of ∼65◦ ,
123
and scalar moment 30–40% that of the total moment, combined with a subsource of near-vertical
124
dip and left-lateral slip, explains the data well.
125
Second, we conduct an analysis of how well we are able to resolve the dip of the mainshock
126
fault plane under the assumption that the fault slipped obliquely on a single planar fault. We
5
127
perform a series of inversions in a grid search over the source geometry. The strike is fixed to either
128
252◦ (for a north-dipping nodal plane) or 72◦ (for a south-dipping nodal plane), the rake is varied
129
between −45◦ and +45◦ and the dip is varied between 55◦ and 90◦ , in 5◦ increments, in an approach
130
similar to that taken by Henry et al. (2000) for the Antarctic plate earthquake. The residual misfit
131
between observed and synthetic waveforms is shown in Figure 2a. We find two minima in the
132
misfit function, with the deeper minimum corresponding to the best-fit double-couple solution
133
described earlier, with a north-dipping fault plane. The shallower minimum corresponds to a south-
134
dipping fault plane, with strike 72◦ , dip 65◦ and rake 25◦ . The residual variance is dominated by
135
the contribution from the long-period mantle waves, and the difference in misfit for the north-
136
and south-dipping solutions is relatively small. However, the body waves for the south-dipping
137
fault plane are fit poorly, especially at several stations in nodal directions. An example of the
138
difference in waveform fits to the body waves for the north- and south-dipping fault planes is
139
shown in Figure 2b. We conclude that the fault plane must indeed dip to the north, under the
140
assumption that all of the slip occurred on a single planar fault.
141
3.2
142
The most surprising result of our CMT analysis is that nearly all of the aftershocks for which
143
we are able to obtain solutions show reverse faulting (Fig. 1). Indeed, we find only two after-
144
shocks, an MW 4.2 event on January 16 and an MW 4.6 event on February 23, both located very
145
close to the mainshock hypocenter, that show dominantly strike-slip motion (Fig. 1). Most of
146
the reverse-faulting events exhibit steeply dipping (30◦ –45◦ ) nodal planes, though a few have one
147
nodal plane of shallower dip. One event, which occurred off the south coast of Haiti (January 15,
148
2010; MW 4.6), shows underthrusting on a plane dipping 13◦ to the north. All of the events are
149
found to be shallow (≤22 km), with most solutions returning depths of 12 km, the minimum depth
150
allowed for standard CMT inversions in the absence of additional depth constraints.
The aftershock sequence
151
Aftershocks occurring immediately after the mainshock can be difficult to analyze because
152
of interference from the large mainshock surface waves at all stations. We have paid particular
6
153
attention to these early aftershocks to assess whether they might exhibit transcurrent, rather than
154
reverse, motion. In several cases, we have performed joint inversions for earthquakes occurring
155
close in time to confirm that interference between wave packets does not bias our results. We find
156
that even those events occurring within the first hours after the mainshock are dominated by reverse
157
motion, including a MW 6.0 event seven minutes after the mainshock.
158
The directions of maximum compression for the reverse-faulting events are oriented NE–SW in
159
all but three cases, with P-axis azimuths ranging from 0–50◦ , and most falling in the range 5–35◦ .
160
We find some suggestion for two preferred P-axis orientations, one near 10◦ and one near 30◦ , but
161
the clustering is not strong. We believe the variability in retrieved CMT parameters reflects true
162
variability in the geometry of the earthquake sources: the relative orientations of the individual
163
sources are well constrained by our analysis, which uses a nearly identical subset of stations for
164
earthquakes of similar magnitude. The variation in source geometry is also clear in many of the
165
waveforms, as shown in Figure 3.
166
3.3
167
We are able to obtain CMT solutions for four earthquakes, of MW = 4.3–4.9, occurring prior to
168
the January 2010 mainshock. The focal mechanisms we retrieve for the pre-mainshock events are
169
consistent with those observed for the aftershock sequence: three of the four moment tensors show
170
reverse faulting, with the fourth showing strike-slip faulting on an approximately E–W trending
171
nodal plane. The reverse-faulting events are located to the west of the January 2010 mainshock,
172
and the geometry of the events occurring in the aftershock zone is similar to that observed for the
173
2010 sequence. The strike-slip event is located to the east of the 2010 mainshock, in a region of
174
relatively weak aftershock activity. One event (December 31, 1990) for which we are unable to
175
obtain a robust CMT solution nonetheless appears to have both a location and source geometry
176
similar to the underthrusting event of January 15, 2010, off the south coast. As for the aftershocks,
177
the P-axis orientations of these earlier events lie in the range 0–50◦ .
Earthquakes prior to 2010
7
178
4
Discussion and Conclusions
179
The dominance of reverse faulting in the aftershock sequence for this large strike-slip earthquake
180
is unusual, and we are not aware of previous examples of aftershock sequences which are both so
181
different from the mainshock geometry and so internally consistent. While the 1989 Loma Prieta
182
earthquake generated an aftershock sequence in which many events differed in geometry from
183
the mainshock, the aftershocks also exhibited great internal variability, with examples of left- and
184
right-lateral strike-slip, normal, and reverse faulting (Beroza & Zoback, 1993).
185
The locations of the Haiti aftershocks are distributed over a wide area, mostly to the west of
186
the mainshock hypocenter. The centroid locations we determine are systematically shifted to the
187
north with respect to the hypocenter locations reported by the NEIC, probably as a result of station
188
coverage dominated by North American stations and because of the very slow raypaths through
189
the Gulf of Mexico and northern Caribbean. However, the centroid locations remain as widely
190
distributed as the reported hypocenter locations, and the combination of geographical distribution
191
of the earthquake locations and the variation in focal geometry suggest that the aftershocks occur
192
on multiple, distributed fault structures, rather than on a single reverse fault.
193
Nearly all of the aftershocks occur on planes striking WNW–ESE. If the reverse component of
194
the mainshock occurred on a separate reverse fault, rather than as oblique slip on the Enriquillo
195
fault, our analysis suggests that this reverse fault strikes ENE–WSW to E–W, like the Enriquillo
196
fault itself, and that it must be large enough to accommodate an earthquake of approximately
197
MW 6.8. However, further knowledge of the accommodation of reverse motion during the main-
198
shock will require detailed analysis of higher-frequency body waves and satellite remote-sensing
199
data.
200
The reverse motion we observe in the Haiti aftershocks is consistent with the presence of mul-
201
tiple thrust structures mapped in the region (Mann et al., 1995) and with a measured component
202
of compression across the island of Hispaniola (Manaker et al., 2008). However, previous studies
203
of strain partitioning in the northern Caribbean have concluded that the overall east-northeastward
204
motion is divided between the Enriquillo and Septentrional strike-slip faults on land and low-angle
8
205
underthrusting structures off the north and southeast coasts of Hispaniola (Mann et al., 2002; Man-
206
aker et al., 2008). Our results, from the aftershock sequence and earlier earthquakes, indicate that
207
strain partitioning in southwest Hispaniola occurs through left-lateral slip on the Enriquillo fault
208
and reverse slip on adjacent high-angle faults. We infer that many anticlinal structures observed on
209
land (Mann et al., 1995) are fault cored.
210
The prevalence of reverse faulting for the earthquakes analyzed, apart from the January 12,
211
2010, mainshock, emphasizes the need to incorporate seismogenic slip on compressional structures
212
into hazard assessments for southern Haiti. While the reverse events appear to occur on multiple
213
fault structures, rather than a single, large thrust fault, probably limiting the maximum size of such
214
events, even earthquakes of MW 4–5 are large enough to cause damage at local distances. Further,
215
we see some evidence for thrust faulting off the south coast of Haiti with geometry similar to that
216
of larger underthrusting events that have occurred to the east in the Dominican Republic. The
217
seismic deformation occurring on reverse faults should also be taken into account in stress-transfer
218
models like those used to assess probable loading on the Enriquillo fault and its branches (e.g., Lin
219
et al., 2010).
220
Acknowledgments
221
We thank R. S. Stein, F. Waldhauser, T. Diehl, N. Seeber, and G. Ekström for suggestions and
222
discussions. The GSN data were collected and distributed by IRIS and the USGS. We thank the
223
operators of the GSN, LCSN, Geoscope, and Geofon for collecting and archiving the seismic data
224
used here. This work was supported by NSF awards EAR-0824694 and EAR-0710842.
9
225
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Ekström, G., Morelli, A., Boschi, E. & Dziewonski, A. M., 1998. Moment tensor analysis of the
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Figure captions
278
Figure 1. Top: Focal mechanisms for 50 earthquakes of the January 12, 2010, Haiti mainshock–
279
aftershock sequence. Bottom: Focal mechanisms for four earthquakes occurring in 1990–2008,
280
prior to the 2010 mainshock. All events are plotted at the NEIC epicentral locations. The mecha-
281
nisms shown in gray are less well constrained than those shown in red.
282
Figure 2. (a) Residual misfit for pure double-couple solutions, with strike 252◦ (left side of image)
283
and 72◦ (right side of image) and varying rake and dip; note non-linear color bar. There are two
284
minima, one for the north-dipping fault plane (left) and one for the south-dipping fault plane (right).
285
The residual misfit for the north-dipping plane is slightly smaller than that for the south-dipping
286
plane. (b) An example of waveform fits to the body waves for the solutions corresponding to the
287
two minima in (a). Shown is the vertical component of displacement (blue: data; red: model),
288
band-pass filtered between 50 and 150 seconds, from station KDAK (Alaska), at a distance of 69◦
289
and azimuth of 326◦ . Shaded regions lie outside the body-wave window and are excluded from the
290
inversion.
291
Figure 3. Observed (blue) and synthetic (red) surface-wave seismograms (vertical component of
292
displacement) for events 201001130132A (black arrows) and 201001130136A (green arrows) at
293
several stations located at epicentral distance ∆ and azimuth α. All records are band-pass filtered
294
between 50 and 150 seconds. The relative amplitudes of the arrivals for the two events vary with
295
azimuth, indicating different focal geometries for the two events, which have similar depths and
296
source locations. The filter used in the analysis is acausal, leading to the apparent arrival of surface-
297
wave energy prior to the event onset (0 seconds).
12
Figures
Figure 1: Top: Focal mechanisms for 50 earthquakes of the January 12, 2010, Haiti mainshock–aftershock
sequence. Bottom: Focal mechanisms for four earthquakes occurring in 1990–2008, prior to the 2010
mainshock. All events are plotted at the NEIC epicentral locations. The mechanisms shown in gray are less
well constrained than those shown in red.
13
(a)
(b)
0.900
North-dipping fault plane
0.800
0.700
0.600
0.500
0.450
0.400
South-dipping fault plane
0.350
0.320
0.310
0.305
0.300
0.295
Figure 2: (a) Residual misfit for pure double-couple solutions, with strike 252◦ (left side of image) and 72◦
(right side of image) and varying rake and dip; note non-linear color bar. There are two minima, one for the
north-dipping fault plane (left) and one for the south-dipping fault plane (right). The residual misfit for the
north-dipping plane is slightly smaller than that for the south-dipping plane. (b) An example of waveform
fits to the body waves for the solutions corresponding to the two minima in (a). Shown is the vertical
component of displacement (blue: data; red: model), band-pass filtered between 50 and 150 seconds, from
station KDAK (Alaska), at a distance of 69◦ and azimuth of 326◦ . Shaded regions lie outside the body-wave
window and are excluded from the inversion.
14
∆ = 1.7, α = 69
∆ = 2.6, α = 307
∆ = 14, α = 237
∆ = 30, α = 188
Figure 3: Observed (blue) and synthetic (red) surface-wave seismograms (vertical component of displacement) for events 201001130132A (black arrows) and 201001130136A (green arrows) at several stations
located at epicentral distance ∆ and azimuth α. All records are band-pass filtered between 50 and 150 seconds. The relative amplitudes of the arrivals for the two events vary with azimuth, indicating different focal
geometries for the two events, which have similar depths and source locations. The filter used in the analysis
is acausal, leading to the apparent arrival of surface-wave energy prior to the event onset (0 seconds).
15
∗
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
11
12
13
14
15
∗
16
17
∗
18
19
∗
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
∗
38
39
40
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
2010
51
52
53
54
2
3
3
4
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
5
8
1
1
1
1
1
1
23
1
28
15
22
23
24
25
25
26
26
27
4
22
15
15
15
16
17
17
20
20
21
21
13
13
13
13
13
14
14
14
14
15
13
13
13
13
13
13
13
13
13
13
28
28
12
5
12
12
13
13
13
13
D
6
10
7
13
12
2
21
12
18
11
14
0
5
9
13
20
21
16
17
18
11
15
16
16
12
12
14
21
22
5
8
10
12
8
1
2
5
5
5
5
6
6
7
12
19
21
0
9
21
22
0
1
1
1
h
26
37
16
4
54
29
51
30
40
16
3
57
0
36
41
4
4
0
51
19
3
12
45
54
41
53
43
26
21
3
15
32
39
56
57
11
3
18
24
49
24
58
23
28
29
22
58
49
53
0
59
32
36
55
m
24.7±0.5
36.0±0.7
19.0±0.4
59.4±0.4
16.7±0.6
18.8±0.8
58.4±0.9
22.7±0.8
30.5±0.2
60.0±0.8
16.2±0.9
27.1±0.3
2.5±0.7
7.5±0.6
42.7±0.5
13.1±0.6
50.3±0.6
0.5±0.5
11.0±0.7
20.4±0.6
47.6±0.1
13.1±0.8
22.6±0.3
10.8±0.2
45.4±0.6
52.3±0.6
46.7±0.2
17.4±0.3
17.0±0.3
8.4±0.6
43.8±0.4
27.4±0.6
4.1±0.3
6.6±0.3
37.0±0.3
31.3±1.1
0.1±0.1
5.7±0.2
3.2±0.5
25.1±1.0
19.2±0.6
27.4±0.7
3.4±0.3
26.5±0.6
8.2±0.3
47.0±0.7
3.3±0.6
22.0±0.5
17.1±0.1
46.1±0.6
10.3±0.9
47.7±0.3
36.5±0.3
17.3±0.9
Time
sec
indicates less-well constrained event (see text).
∗
∗
41
42
43
∗
44
45
46
47
48
∗
49
∗
50
∗
∗
∗
∗
∗
1990
1990
2005
2008
2010
2010
2010
2010
2010
2010
Date
Y
M
1
2
3
4
5
6
7
8
9
10
No.
3.8
0.2
1.7
0.6
2.9
-0.8
3.2
2.1
1.9
0.2
0.2
0.1
1.3
4.4
-0.9
1.1
3.1
4.6
2.1
0.0
4.3
2.2
0.9
1.2
1.2
4.9
1.9
1.0
3.6
1.8
1.5
-1.4
0.8
1.6
2.4
0.6
2.6
3.2
0.9
2.2
3.2
1.3
-0.5
1.8
3.4
1.3
3.3
5.6
6.9
4.6
5.2
3.5
5.1
1.3
δt0
18.62±.02
18.72±.05
18.61±.03
18.78±.03
18.81±.05
18.73±.07
18.60±.13
18.77±.05
18.64±.02
18.63±.05
18.22±.08
18.65±.02
18.68±.04
18.65±.04
18.44±.05
18.37±.07
18.05±.04
18.69±.03
18.68±.07
18.64±.04
18.67±.00
18.51
18.72±.03
18.63±.02
18.60±.06
18.67±.07
18.71±.01
18.64±.02
18.67±.02
18.67±.04
18.46±.04
18.45±.05
18.66±.02
18.47±.03
18.64±.02
18.59±.08
18.64±.01
18.51±.02
18.57±.05
18.72±.05
18.69±.05
18.62±.04
18.56±.03
18.72±.05
18.58±.03
18.63±.03
18.48±.03
18.83±.04
18.61±.00
18.58±.06
18.66±.06
18.63±.02
18.60±.02
18.59±.07
0.17
0.31
0.15
0.23
0.33
0.23
0.09
0.26
0.15
0.13
-0.17
0.27
0.18
0.16
0.34
0.17
0.04
-0.12
-0.07
0.24
0.10
0.17
0.25
0.25
0.26
0.27
0.15
0.32
0.18
0.12
0.01
0.30
0.07
0.24
0.18
0.26
0.19
0.12
0.30
0.31
0.18
0.17
0.31
0.12
0.21
0.01
0.27
0.16
0.19
0.31
0.21
0.20
0.26
Centroid Parameters
Latitude
λ
δλ0
-72.55±.03
-72.96±.07
-72.94±.04
-72.95±.04
-72.97±.08
-71.96±.08
-72.74±.15
-73.13±.08
-72.94±.03
-72.98±.10
-72.01±.12
-73.03±.03
-72.48±.06
-72.57±.03
-72.79±.05
-72.73±.05
-72.34±.05
-72.44±.02
-72.77±.09
-72.84±.08
-72.81±.01
-72.79
-72.82±.03
-72.86±.03
-73.44±.07
-72.92±.08
-72.95±.02
-72.52±.03
-72.52±.04
-72.97±.05
-72.86±.05
-72.88±.06
-72.88±.04
-72.81±.04
-73.02±.03
-73.23±.10
-72.92±.01
-72.83±.02
-72.89±.06
-72.96±.09
-73.07±.05
-72.93±.07
-72.95±.04
-73.05±.08
-72.79±.04
-72.62±.07
-72.45±.04
-73.63±.03
-72.62±.01
-72.88±.06
-72.97±.08
-72.98±.03
-72.98±.03
-73.08±.08
0.04
-0.11
-0.06
-0.15
-0.52
0.01
-0.10
-0.16
0.01
0.20
0.13
-0.11
0.29
-0.01
0.03
-0.12
0.03
0.10
-0.04
0.10
-0.23
0.01
0.00
-0.60
-0.11
-0.02
-0.02
0.05
-0.10
-0.11
-0.16
-0.16
0.03
-0.14
-0.20
-0.02
0.06
-0.08
0.01
-0.18
-0.03
-0.11
-0.24
0.11
0.24
-0.14
-0.07
-0.07
-0.09
-0.16
-0.12
-0.15
-0.23
Longitude
φ
δφ0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
20.4± 2.7
12.0
12.0
12.0
12.0
18.0± 2.3
12.0
12.0
12.0
16.8± 2.3
12.0
12.0
12.0
12.0
21.3± 3.4
12.7± 3.7
12.0
12.0
14.0± 1.4
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
14.1± 1.2
12.0
12.0
17.5± 2.1
12.0
12.0
12.0
12.0
12.0
12.0
19.2
12.0
12.0
12.0
13.5± 1.3
13.2± 1.4
14.1± 3.7
-4.6
6.8
8.0
4.0
11.3
2.7
7.5
4.1
3.5
3.2
4.1
Depth
h
δh0
1.1
1.0
1.0
1.1
1.0
1.0
1.0
1.0
0.6
1.0
1.0
1.2
1.0
1.1
0.7
0.7
0.7
0.5
0.4
0.5
2.1
0.6
0.7
0.7
0.6
1.0
0.9
0.7
0.6
0.6
0.5
0.5
0.7
0.6
1.4
1.3
1.9
1.1
0.8
1.1
0.6
0.5
0.6
1.0
1.1
1.1
1.0
1.0
8.1
3.1
1.5
1.6
1.5
1.2
Half
Drtn
23
22
23
22
22
22
22
22
23
22
22
23
22
22
22
23
23
22
22
23
25
22
23
23
23
22
23
23
23
22
23
22
23
23
24
23
24
24
23
23
23
23
23
22
23
23
22
22
26
25
24
24
24
23
Scale
Factor
10ex
1.0
3.8
0.9
6.4
3.3
1.3
2.7
4.0
2.3
4.4
5.4
1.9
2.6
7.4
6.7
1.0
1.1
6.6
5.3
0.9
0.7
2.5
2.8
2.3
0.8
3.2
5.8
3.0
2.0
6.7
1.0
8.2
2.4
1.1
1.8
3.3
5.4
0.9
2.1
0.8
1.5
1.2
1.9
3.5
3.3
0.9
3.8
8.3
4.4
1.2
0.9
3.4
2.8
6.3
M0
0.24±0.08
3.43±0.33
0.93±0.04
6.35±0.31
2.07±0.28
1.19±0.19
2.78±0.32
3.55±0.34
2.36±0.06
4.14±0.42
4.98±1.46
1.95±0.06
2.16±0.24
2.69±0.47
6.11±0.43
0.72±0.15
0.51±0.04
-0.63±0.45
5.67±0.38
0.85±0.16
0.76±0.00
1.57±0.23
2.82±0.08
2.24±0.06
0.51±0.15
2.93±0.89
5.87±0.09
2.75±0.07
1.93±0.16
4.60±0.35
0.73±0.06
6.25±0.47
2.27±0.08
0.87±0.05
1.84±0.05
2.38±0.48
5.53±0.05
0.77±0.07
1.97±0.13
0.76±0.09
1.31±0.23
1.09±0.10
1.81±0.07
2.95±0.29
3.40±0.17
1.01±0.12
0.74±0.41
5.89±0.82
1.74±0.02
1.22±0.08
0.81±0.10
3.34±0.28
2.80±0.26
5.84±1.62
Mrr
-0.14±0.07
-2.95±0.29
-0.76±0.04
-5.23±0.31
-3.24±0.25
-0.98±0.19
-1.99±0.32
-3.50±0.31
-2.07±0.06
-3.85±0.38
-2.56±0.91
-1.78±0.06
-2.24±0.21
-3.70±0.38
-3.97±0.50
-0.18±0.10
-0.45±0.04
-4.78±0.40
-4.36±0.36
-0.75±0.12
-0.63±0.00
-1.32±0.24
-2.12±0.08
-2.12±0.06
-0.79±0.16
-1.42±0.55
-5.62±0.08
-2.56±0.07
-1.55±0.11
-3.89±0.32
-0.57±0.06
-3.83±0.56
-2.01±0.08
-0.52±0.05
-1.58±0.05
-2.69±0.38
-4.83±0.05
-0.38±0.04
-1.21±0.14
-0.78±0.08
-0.86±0.17
-1.06±0.08
-1.50±0.07
-2.83±0.29
-3.01±0.12
-0.83±0.07
-2.89±0.31
-1.83±0.62
-3.87±0.02
-0.91±0.08
-0.70±0.09
-3.03±0.19
-2.74±0.17
-4.66±1.15
Mθθ
-0.11±0.06
-0.48±0.30
-0.17±0.04
-1.12±0.28
1.17±0.29
-0.22±0.16
-0.78±0.30
-0.06±0.30
-0.28±0.05
-0.29±0.35
-2.42±0.98
-0.17±0.06
0.09±0.19
1.01±0.40
-2.14±0.35
-0.54±0.09
-0.06±0.03
5.42±0.34
-1.31±0.36
-0.11±0.07
-0.13±0.00
-0.25±0.21
-0.70±0.08
-0.12±0.06
0.27±0.09
-1.51±0.46
-0.26±0.08
-0.19±0.07
-0.38±0.09
-0.72±0.28
-0.16±0.06
-2.41±0.41
-0.26±0.08
-0.35±0.04
-0.26±0.05
0.31±0.45
-0.69±0.05
-0.39±0.04
-0.76±0.12
0.02±0.08
-0.45±0.12
-0.03±0.08
-0.31±0.07
-0.12±0.25
-0.39±0.19
-0.18±0.13
2.14±0.36
-4.06±0.51
2.13±0.02
-0.31±0.09
-0.11±0.08
-0.31±0.14
-0.06±0.12
-1.17±0.79
-0.53±0.17
-0.92±1.06
-0.10±0.13
-1.68±1.07
-1.14±1.12
0.29±0.46
-0.74±2.46
-1.62±1.09
0.38±0.23
1.54±1.36
2.33±0.99
0.45±0.20
-0.43±0.60
-6.21±0.97
2.75±1.62
0.64±0.22
0.95±0.13
3.67±0.93
0.83±2.45
0.18±0.20
-0.02±0.01
1.85±0.41
-0.74±0.41
0.22±0.23
0.14±0.15
-0.83±1.26
0.62±0.33
1.35±0.32
-0.38±0.22
4.18±1.06
0.62±0.22
5.37±1.73
-0.14±0.32
0.63±0.17
0.13±0.13
-1.71±0.84
-0.14±0.12
-1.00±0.77
-1.24±0.53
-0.14±0.38
0.55±1.65
-0.87±0.83
-0.15±0.27
-0.41±1.42
-0.46±1.06
-0.14±0.19
1.33±0.39
0.92±1.01
2.22±1.38
0.14±0.16
-0.16±0.12
-1.55±0.93
0.57±1.65
-0.04±0.17
-0.04±0.01
-0.20±0.43
-0.31±0.38
-0.47±0.22
-0.43±0.12
-0.36±0.97
0.06±0.38
-0.48±0.32
0.29±0.25
-2.79±0.82
-0.27±0.19
-1.46±1.59
-0.70±0.29
0.03±0.15
-0.42±0.17
-1.53±1.13
-0.11±0.17
0.25±0.06
-0.51±0.42
0.10±0.20
-0.07±0.20
-0.27±0.32
-0.81±0.24
-0.60±0.50
-0.85±0.77
0.72±0.78
-1.06±0.10
0.19±0.27
-0.26±0.19
0.21±0.29
-0.31±0.26
-3.02±1.40
0.43±0.88
-4.57±0.99
-0.53±0.10
-0.03±0.41
-0.36±0.27
-0.97±0.33
-0.13±0.25
-0.86±1.69
-0.11±0.16
-1.05±1.46
0.18±0.17
-0.10±0.07
0.58±0.66
-0.02±0.24
-0.74±0.29
-0.47±0.26
0.19±0.30
-1.45±1.31
-0.24±0.41
Mrφ
-0.14±0.63
Elements of Moment Tensor
Mφφ
Mrθ
0.85±0.04
0.87±0.25
0.14±0.03
1.89±0.22
0.01±0.25
0.50±0.12
0.67±0.33
0.08±0.29
0.46±0.05
-0.83±0.39
2.18±0.63
0.18±0.05
-0.52±0.16
2.59±0.29
2.48±0.37
0.35±0.06
0.07±0.04
1.83±0.32
1.07±0.37
0.32±0.06
0.21±0.00
0.67±0.21
0.93±0.07
0.39±0.05
0.08±0.08
1.80±0.26
0.21±0.08
0.18±0.07
-0.84±0.06
1.29±0.25
0.46±0.04
2.68±0.37
0.73±0.06
0.49±0.03
0.23±0.04
1.04±0.41
1.22±0.04
0.61±0.02
0.85±0.10
-0.04±0.06
0.60±0.07
0.02±0.07
0.59±0.06
1.21±0.23
0.47±0.09
0.19±0.05
2.64±0.28
4.48±0.39
2.74±0.01
0.50±0.05
0.23±0.05
0.81±0.08
0.21±0.07
1.91±0.45
Mθφ
Supplementary Table 1. Centroid–moment-tensor solutions for 54 earthquakes occurring in southern Haiti, 1990–5/2010. Headings are as in standard Global CMT reports (Ekström et al., 2005).