Geophysical Research Letters
Supporting Information for
Dynamic rupture models of earthquakes on the Bartlett Springs Fault, northern California
Julian C. Lozos 1,2 , Ruth A. Harris 2 , Jessica R. Murray 2 , and James J. Lienkaemper 2
1. Stanford University, 2. USGS Menlo Park
Peer-Review DISCLAIMER: This draft manuscript is distributed solely for purpose of scientific peer review. Its content is merely being considered for publication, so it is not to be disclosed or released by reviewers. Until the manuscript has been approved for publication by the U.S. Geological Survey (USGS), it does not represent any official
USGS finding or policy.
Contents of this file
Figures S1 to S4
Tables S1 to S2
Introduction
This supplemental material describes the literature-based velocity structure implemented in our models, a well as stress states and results for additional models, which incorporate error bars in creep rates and locking depth. This supplement contains a table (S1) describing the velocity structure, a table (S2) describing the input stress parameters for these additional models, and four figures (S1-S4) of slip distribution from these models.
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Figure S1. Slip distribution for M2014 model ruptures using stress states X and Z, under both uniform traction and a regional stress field. When compared to case Y (in the body of the paper), the overall pattern of slip is the same: symmetrical within the locked patch in the uniform traction model, and with additional slip to the SE (right) in the regional stress model.
Case Z, in which there is no negative stress drop, experiences some coseismic slip in the slipneutral creeping regions below 5 km depth, but this slip is still minimal compared to that in the locked region.
Figure S2. Slip distributions for models using stress states I and O, based on the upper and lower error bars on creep rate for the M2014 model, under both uniform traction and a regional stress field. The overall distribution of slip is consistent between these models. Case O, which has a lower creep rate and therefore more locking, does have a lower moment than mean case
Y or upper error bar case I.
Figure S3. Slip distributions for L2014 models using mean locking depths in stress state S, in which the fastest creeping regions of the fault experience a zero stress drop. Under both uniform traction and a regional stress field, and for all locking depths, case S permits a larger amount of slip in the creeping regions than for case R, shown in the main text.
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Figure S4. Slip distributions for models using stress states U and V, representing the upper and lower error bars on creep rate for the L2014 model, and mean locking depths. Stress state U has the least contrast in stress drop, and therefore allows the largest amount of slip into the creeping regions. Case V has the most contrast in properties, and does not permit much slip outside of the fully locked patches.
1D velocity structure for the Bartlett Springs Fault
Depth (km below ground surface)
Vp (km/s) Vs (km/s)
0
1.5
3.5
4.39
5.54
5.62
2.54
3.2
3.25
5
7.5
10
12.5
5.65
5.72
5.79
5.97
3.26
3.3
3.34
3.45
15
20
6.08
6.68
3.51
3.86
25 6.78 3.91
30 7.8 4.5
Table S1. Local 1D velocity structure for the Bartlett Springs region, based on station delays for local microseismicity, from Castillo and Ellsworth (1993). We implement this velocity structure in all dynamic rupture models included in the present study.
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M2014 case X: positive stress drop only in locked regions
Creep rate  d
 s
Stress drop
-0.6 mm/yr 0.2
4.4 mm/yr 0.43487445362
4.6 mm/yr 0.43487445362
7.0 mm/yr 0.54995
0.6 9 MPa
0.6 0 MPa
0.6 0 MPa
0.6 -4.41 MPa
7.8 mm/yr 0.58674 0.6 -5.82 MPa
M2014 case Z: fastest creep rate corresponds to neutral stress drop
Creep rate  d
 s
Stress drop
-0.6 mm/yr 0.2 0.6 9 MPa
4.4 mm/yr
4.6 mm/yr
7.0 mm/yr
-0.2 mm/yr
5.2 mm/yr
5.9 mm/yr
0.33989
0.34537
0.41243
7.8 mm/yr 0.43487445362
M2014 case I: mean creep rates
Creep rate
 d
 s
0.2
0.34746
0.36651
0.6 3.64 MPa
0.6 3.43 MPa
0.6 0.86 MPa
0.6 0 MPa
Stress drop
0.6 9 MPa
0.6 3.35 MPa
0.6 2.62 MPa
0.6 0 MPa
0.6 -0.63 MPa
8.4 mm/yr 0.43487445362
9.0 mm/yr 0.451314
M2014 case O: mean creep rates -
Creep rate
 d
 s
-1.0 mm/yr
3.3 mm/yr
3.6 mm/yr
5.8 mm/yr
0.2
0.3485
0.35894
0.43487445362
6.6 mm/yr 0.46254
Stress drop
0.6 9 MPa
0.6 3.31 MPa
0.6 2.91 MPa
0.6 0 MPa
0.6 -5.9686 MPa
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L2014 case S: fastest creep rate corresponds to neutral stress drop
Creep rate  d
 s
Stress drop
“Locked”
-0.2 mm/yr
2.5 mm/yr
0.2
0.2
0.337875
4.4 mm/yr 0.43487445362
L2014 case U: mean creep rates +1 
Creep rate  d
 s
“Locked” 0.2
0.7 mm/yr
3.75 mm/yr
0.36964
0.43487445362
4.1 mm/yr 0.45517
L2014 case V: mean creep rates -1 
Creep rate
 d
 s
“Locked” 0.2
0.6 9 MPa
0.6 9 MPa
0.6 3.7174 MPa
0.6 0 MPa
Stress drop
0.6 9 MPa
0.6 2.25 MPa
0.6 0 MPa
0.6 -0.7778 MPa
Stress drop
0.6 9 MPa
-1.1 mm/yr
1.5 mm/yr
0.2
0.43487445362
0.6 9 MPa
0.6 0 MPa
3.7 mm/yr 0.633586 0.6 -7.6154 MPa
Table S2. List of tables for additional stress states used in dynamic rupture models of the
Bartlett Springs Fault. Case X is for a M2014 model with positive stress drop in only the locked patch, while case Z is a M2014 model with even the fastest creeping regions represented with zero stress drop/slip-neutral behavior. Cases I and O represent the upper and lower error bars on creep rate respectively, also for the M2014 model. Case S is for a L2014 model in which the fastest creep rate corresponds with zero stress drop/slip-neutral behavior. Cases U and V represent the upper and lower error bars on creep rate for the L2014 model.
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