Nicoya earthquake rupture anticipated by geodetic ......Supplementary Text for “Nicoya earthquake rupture anticipated by geodetic measurement of the locked plate interface” By:

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Supplementary Text for “Nicoya earthquake rupture anticipated by geodetic measurement of the locked plate interface”

By: Marino Protti1, Victor González1, Andrew V. Newman2*, Timothy H. Dixon3, Susan Y. Schwartz4, Jeffrey S. Marshall5, Lujia Feng6, Jacob I. Walter2, Rocco Malservisi3, Susan E. Owen7

Marino Protti1, Victor González1, Andrew V. Newman2*, Timothy H. Dixon3, Susan Y. Schwartz4, Jeffrey S. Marshall5, Lujia Feng6, Jacob I. Walter2, Rocco Malservisi3, Susan E. Owen7

1. Observatorio Vulcanológico y Sismológico de Costa Rica (OVSICORI), Universidad Nacional, Apartado 1718-3000, Heredia 3000, Costa Rica

2. School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340, USA

3. Department of Geology, University of South Florida, 4202 E Fowler Ave, Tampa, FL 33620, USA

4. Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA.

5. Geological Sciences Department, Cal Poly Pomona, 3801 West Temple Ave., Pomona, CA, 91768, USA

6. Earth Observatory of Singapore, Nanyang Technological University, 50 Nanyang Avenue, Block N2-1A-15, 639798, Singapore.

7. Jet Propulsion Laboratory, MS 238-600, 4800 Oak Grove Drive, Pasadena, CA 91109

* corresponding author

Nicoya earthquake rupture anticipated by geodetic measurement of the locked plate interface

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NGEO2038

NATURE GEOSCIENCE | www.nature.com/naturegeoscience 1

© 2013 Macmillan Publishers Limited. All rights reserved.

http://www.nature.com/doifinder/10.1038/ngeo2038

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Seismic methods:

From seismic data recorded by the University of California Santa Cruz and Georgia Tech seismic networks on Nicoya, we identify the P and S phase arrivals utilizing a tuned automatic Short-term/Long-term average ratio filter provided with the Antelope Seismic Database software (www.brtt.com). The automatic choice of phase arrivals and event associations are subsequently reviewed by an analyst for accuracy and consistency. The phase information were then used to relocate events within a local three-dimensional velocity model1 using the software SIMULPS2. Figure 1 includes aftershocks that indicate horizontal formal errors of less than 1 km based on travel-time residuals between predicted and observed station arrival times. The epicenter of the mainshock is shown as the first-motion point source, based on the network-observed initial P-wave arrivals.

GPS processing and coseismic displacement fields:

Using funding obtained by the NSF-RAPIDS program, within 3 days of the earthquake a team comprising individuals from OVSICORI, University of South Florida, Georgia Tech, UC Santa Cruz, and Cal Poly Pomona began arriving in Nicoya to repair continuous GPS and seismic stations, and perform a rapid field campaign. All campaign GPS sites were occupied for a minimum of three-days, while several remained longer to capture ongoing postseismic deformation.

Syn-field Processing: Following the earthquake, daily and 5-minute kinematic positions for both campaign and

continuous data were processed as they were downloaded, either through routine telemetric communications already established or from individuals during the field deployment. The data were processed using single station bias fixing3 and point-positioning4 with JPL’s GIPSY-OASIS software. For the rapid estimates immediately following the earthquake, the JPL Rapid orbit and clock files were used5.

These early results were used during the active field campaign to evaluate the quality of GPS coverage in order to establish priorities for additional data collection from new and already measured stations, and for prioritizing continuous GPS repairs. Once early displacement fields were made, preliminary slip inversions were also made to evaluate the spatial extent of rupture. Post-Processing:

All GPS data collected during the field experiment were processed or reprocessed later and in a consistent manor using JPL’s final orbit products at the USF Geodesy lab. From these data the final GPS displacement field was created from the combination of data from campaign and continuous GPS data collected before and after the earthquake.

Displacements: For all GPS data the displacements ud were determined by differencing the post-event

position u1 and the combination of the last observed pre-event position u0 and the expected continued interseismic deformation from the product of the observed velocity v as reported in the Feng study6, and the time lapse between observation and earthquake t, such that:

ud = u1 ! (u0 + vt) .

2 NATURE GEOSCIENCE | www.nature.com/naturegeoscience

SUPPLEMENTARY INFORMATION DOI: 10.1038/NGEO2038



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For the 21 campaign sites, the estimated pre-event positions were measured during a campaign in March 2010, leaving t = 2.53 years. After the earthquake, new stations were occupied as rapidly as possible, causing many sites to have very short-observations on their first day. To avoid problems introduced with such error-prone results, the post-earthquake positions were taken from the first subsequent daily-averaged GPS solution with a formal horizontal position error under 5 mm.

For the 18 continuous GPS stations, the displacement determination was performed in the same manner as the campaign sites. For the 9 stations that were operational through the earthquake daily solutions were taken from the days immediately preceding and following the event. Two stations were differenced using data with less than 2 weeks separation around the event. The remaining 7 stations had measurement lapses between about 50 and 500 days before the event. Errors:

The displacement errors σd were determined assuming the errors reported for the interseismic velocities σv (ref. 6), the pre-event positions σ0, and post-event positions σ1 were all independent7, such that:

! d = ! 02 +!1

2 + (! vt)2

where t is the time lapse between the earthquake and the prior event measurement. Errors were on average, approximately 3.2% and 6.7% of the displacement magnitudes for continuous and campaign sites, respectively. As expected, the errors are larger compared to displacements for sites away from the rupture, where deformation falls off. All stations positions, velocities, errors, and measurement lapses are reported in Table S1.

Field Geomorphic Methods:

Geomorphic field measurements were made 5-16 days after the earthquake to constrain coseismic uplift along the Nicoya coast. Uplift was measured at 22 sites using six different methods: 1) pre- vs. post-earthquake rapid altimeter surveying of coastal monuments, 2) reoccupation of pre-earthquake hand-level survey lines, 3) hand-level surveying of pre- vs. post-earthquake high tide debris lines, 4) spot measurements of displaced tidal notches and rock staining, 5) spot measurements of vertical extent of mortality (VEM) for sessile intertidal organisms8,9, 6) spot measurements of coastal stream incision and mangrove root exposure10.

The local survey datum at each site was the tidal still water level (SWL) at the time of surveying. Survey data were adjusted to the mean lower low water (MLLW) datum for regional tidal predictions11-13, and then corrected to corresponding elevations above mean sea level (MSL). An additional correction for wave run-up was applied based on local variations in beach slope14. The results were also adjusted for minor post-seismic deformation as observed by near-field GPS sites during the time period between the earthquake and geomorphic fieldwork.

Measurable coseismic uplift occurred along ~80 km of coastline between Playa Avellanas and Punta Coyote. Pronounced uplift (≥50 cm) occurred along ~30 km of coast from Nosara to Islita, with maximum uplift (≥80 cm) near Puerto Carrillo onshore of the epicenter





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(Figure 3). The observed geomorphic uplift pattern is consistent with that recorded by continuous GPS stations (although GPS values are systematically lower), and with seismic and geodetic inversions for primary slip centered beneath the Nicoya coast (Figure S1). All geomorphic uplift results are reported in Table S2.

Details of Geodetic Inversion methods:

To model the coseismic deformation of the 5 September 2012 Nicoya earthquake, we used the campaign and continuous GPS data, but excluded the geomorphic data collected here because of the increased errors and spatial redundancy with the GPS data. The model geometry, smoothing, and inversion method are the same as those used in the interseismic model and are described in the Feng study6. Although the interseismic and coseismic models share many similarities, they have three major differences: (1) only trench-normal and vertical interseismic annual velocities were used in the interseismic modeling, while all three components of coseismic offsets were used in the coseismic modeling; (2) only the dip-slip component of locking was considered in the interseismic modeling, while both dip-slip and strike-slip components were inverted in the coseismic modeling; (3) virtual back slip was assumed in the interseismic modeling with maximum back slip constrained by the plate convergence, while no maximum slip was applied in the coseismic modeling.

We conducted a separate checkerboard resolution test for the coseismic modeling to assess the spatial resolution of the GPS network on resolving dip-slip and strike-slip along the assumed subduction interface (Figure S2). In these tests we’ve included weighting based on per-station error estimates from the observed displacement field (Table S1) to account for the relative, but small error observed in the real data. Because of the reduced resolution toward the model boundaries, we only consider the high-resolution area that was observable at both low smoothing (κ = 1) and smoothing at the same level as the final model shown in Figure 4 (κ = 18,000).

We ran inversion models at a wide range of smoothing levels. The preferred model at κ = 18,000 (Figure S3b) was chosen because of its location in the inflection corner of the trade-off curve between roughness and misfit (Figure S3d), which introduces substantial smoothing but without the cost of large increasing misfit. For comparison, examples of under-smoothed (Figure S3a) and possibly over-smoothed (Figure S3c) are also provided. All three cases show a major slip patch underneath the Nicoya peninsula and some slip offshore. To test if the slip patch offshore is indeed required, we conducted another set of models with the offshore area constrained to have no coseismic slip. The fits of the constrained models were systematically and substantially worse than the models that allow some slip offshore. However, a more detailed analysis of this shallow slip patch was not conducted due to the low resolution offshore.





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Table S1: Displacement field obtained from a combination of the continuous and campaign GPS stations shown in Figure 2.

Displacement Error time lapse Stat Long. Lat. Elev. E N V E N V Date-‐0 Date-‐1

[°] [°] [m] [mm] [mm] [mm] [mm] [mm] [mm] [yr] [yr] [yr]

Continuous BIJA -‐84.577 9.750 555.6 -‐1.9 -‐17.5 -‐61.3 4.4 5.1 15.7 2011.381 2012.724 1.343

BON2 -‐85.203 9.765 28.0 -‐17.7 -‐280.2 230.5 1.7 1.6 6.6 2011.647 2012.705 1.058 CABA -‐85.344 10.238 27.0 -‐192.1 -‐302.9 -‐112.2 0.8 0.7 2.8 2012.675 2012.680 0.005 ELVI -‐85.446 10.395 81.9 -‐128.9 -‐318.6 -‐90.4 1.2 0.9 4.3 2012.642 2012.713 0.071 EPZA -‐85.568 10.141 668.4 -‐95.0 -‐192.3 270.9 0.8 0.7 2.8 2012.675 2012.680 0.005 GRZA -‐85.636 9.916 39.3 -‐431.2 -‐524.7 460.7 1.7 1.2 5.3 2012.658 2012.697 0.038 HATI -‐85.710 10.292 58.6 -‐67.6 -‐105.7 99.5 1.3 0.9 4.1 2012.544 2012.686 0.142 HUA2 -‐85.352 10.018 593.9 -‐99.1 -‐230.6 196.2 0.9 0.6 2.7 2012.555 2012.686 0.131 IND1 -‐85.502 9.865 75.3 -‐204.4 -‐600.7 505.6 1.0 0.9 4.0 2012.374 2012.686 0.311 LAFE -‐84.960 9.807 65.2 -‐23.2 -‐65.5 12.3 0.8 0.7 3.8 2012.675 2012.680 0.005 LEPA -‐85.031 9.945 20.9 -‐115.5 -‐131.6 11.6 1.3 1.0 4.4 2012.189 2012.708 0.519 LMNL -‐85.053 10.268 103.0 -‐153.5 -‐157.5 -‐69.1 0.8 0.6 2.6 2012.675 2012.680 0.005 PNE2 -‐85.829 10.196 19.5 -‐234.3 -‐107.7 185.6 1.9 1.7 8.2 2011.400 2012.705 1.305 PUJE -‐85.272 10.114 30.1 -‐169.7 -‐241.9 -‐60.7 0.8 0.6 2.6 2012.675 2012.680 0.005 PUMO

-‐84.967 10.064 18.0 -‐129.4 -‐112.4 -‐48.8 0.8 0.7 3.2 2012.675 2012.686 0.011 QSEC -‐85.357 9.840 17.4 -‐46.7 -‐391.7 395.4 0.8 0.7 2.8 2012.675 2012.680 0.005 SAJU -‐85.711 10.067 73.4 -‐343.0 -‐251.9 439.0 0.8 0.7 3.0 2012.675 2012.680 0.005 VERA -‐84.869 10.854 64.3 -‐45.7 -‐64.6 -‐5.7 1.0 0.8 3.5 2012.675 2012.680 0.005 Campaign

BAGA -‐85.261 10.541 123.4 -‐89.0 -‐159.8 -‐75.8 6.5 2.5 11.4 2010.173 2012.702 2.529 BALL -‐85.448 10.383 118.0 -‐121.9 -‐304.1 -‐148.6 5.1 2.0 8.1 2010.175 2012.708 2.533 BONG -‐85.207 9.744 21.6 1.8 -‐283.0 254.4 4.6 2.6 8.9 2010.181 2012.694 2.513 CEBA -‐85.776 10.249 90.4 -‐125.6 -‐67.9 175.1 6.5 2.5 10.3 2010.181 2012.697 2.516 CRUZ -‐85.634 11.054 267.2 18.3 -‐49.1 -‐40.2 7.8 4.0 15.1 2010.189 2012.710 2.521 DIRI -‐85.611 10.272 82.0 -‐50.5 -‐199.3 -‐24.7 5.8 2.2 10.0 2010.181 2012.694 2.513 GRAN -‐85.653 10.562 122.2 -‐12.3 -‐162.2 -‐79.8 4.5 2.0 8.4 2010.184 2012.702 2.518 GUAR -‐85.450 10.140 136.3 -‐115.1 -‐281.0 45.1 6.2 1.9 9.9 2010.162 2012.691 2.529 GUIO -‐85.659 9.923 31.4 -‐412.4 -‐467.9 368.1 4.8 2.3 8.6 2010.170 2012.691 2.521 HOJA -‐85.382 10.079 241.0 -‐131.3 -‐249.2 55.4 7.5 2.3 10.6 2010.175 2012.689 2.514 JICA -‐85.136 9.975 61.4 -‐102.0 -‐156.9 -‐31.1 5.1 2.2 9.4 2010.175 2012.699 2.524 LEON -‐85.187 9.937 276.9 -‐33.2 -‐151.3 63.0 5.3 2.1 8.7 2010.170 2012.689 2.519 MATA -‐85.813 10.355 77.8 -‐34.5 -‐61.9 46.4 6.3 3.0 15.0 2010.186 2012.697 2.511 PALO -‐85.220 10.241 40.0 -‐206.0 -‐247.1 -‐84.5 6.6 2.7 10.7 2010.186 2012.702 2.516 PAQU -‐84.955 9.832 80.3 -‐28.5 -‐72.0 -‐11.3 6.3 2.4 10.1 2010.167 2012.702 2.535 POTR -‐85.569 10.847 155.7 6.1 -‐90.5 -‐66.7 6.3 2.5 10.0 2010.189 2012.713 2.524 SAMA -‐85.549 9.889 45.9 -‐286.7 -‐601.6 531.4 4.6 2.1 8.0 2010.170 2012.691 2.521 SJOS -‐84.948 10.366 1062.1 -‐105.7 -‐120.3 -‐120.7 5.1 2.1 8.3 2010.195 2012.702 2.507 SJUA -‐85.757 10.063 44.6 -‐373.7 -‐271.6 319.4 6.4 2.6 10.5 2010.186 2012.713 2.527 TENO -‐85.098 10.602 373.4 -‐79.0 -‐139.3 -‐57.9 5.2 2.3 9.1 2010.189 2012.716 2.527 VENA -‐85.792 10.161 24.9 -‐258.1 -‐137.7 242.9 5.2 2.1 8.4 2010.184 2012.697 2.513





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Table S2: Geomorphic uplift results shown in Figure 2 and S1.

Ucs-‐m ΔR Ups-‐gps Ucs-‐a # Location Measured Wave Run-‐Up Post-‐Seismic Adjusted RSS Field Site Site

Uplift Correction Correction Uplift Error Method Latitude Longitude (m) (m) (m) (m) (± m) (deg N) (deg W) 1 Playa Langosta (Tamarindo) 0.00 n/a n/a 0.00 0.20 A,B 10.2873 -‐85.8516 2 Playa Avellanas (Avellanas) 0.28 -‐0.04 -‐0.02 0.22 0.20 A,B,C 10.2288 -‐85.8376 3 Playa Callejones (Pochotes) 0.42 -‐0.06 -‐0.02 0.34 0.20 B,C,F 10.1851 -‐85.8239 4 Playa Junquillal (Iguanazul) 0.40 n/a -‐0.02 0.38 0.10 A,E 10.1754 -‐85.8175 5 Playa Cocal (San Juanillo) 0.72 -‐0.11 -‐0.02 0.59 0.20 B,C 10.0314 -‐85.7416 6 Playa Peladas (Nosara) 0.66 -‐0.10 -‐0.03 0.53 0.20 A,C 9.9537 -‐85.6753 7 Playa Guiones Sur

(Punta Guiones) 0.80 -‐0.12 -‐0.03 0.65 0.20 A,B,C 9.9221 -‐85.6608

8 Playa Garza Oeste (Punta Guiones)

0.76 -‐0.11 -‐0.03 0.62 0.20 B,C 9.9075 -‐85.6509

9 Playa Sámara Oeste (Sámara)

0.72 -‐0.11 -‐0.05 0.56 0.20 C 9.8772 -‐85.5331

10 Playa Sámara Este (Punta Indio)

0.73 -‐0.11 -‐0.05 0.57 0.20 C 9.8683 -‐85.5072

11 Playa Carrillo Oeste (Punta Indio)

0.72 -‐0.11 -‐0.05 0.56 0.20 C,F 9.8692 -‐85.4991

12 Playa Carrillo Este (Puerto Carrillo)

0.85 -‐0.13 -‐0.05 0.67 0.20 A,B,C,G 9.8663 -‐85.4828

13 Playa Bejuco (Bejuco) 0.55 n/a -‐0.03 0.52 0.10 E 9.8181 -‐85.3329 14 Playa Caletas

(Punta Coyote) 0.46 -‐0.07 -‐0.03 0.36 0.20 A,B,C 9.7595 -‐85.2692

15 Playa Carmen (Malpaís) 0.00 n/a n/a 0.00 0.20 C 9.6267 85.1522

Explanation Ucs-‐m = Measured Co-‐Seismic Uplift (Tide corrected) ΔR = Wave Run-‐Up Correction (ΔR = Rpre-‐EQ -‐ Rpost-‐EQ)

Ups-‐gps = Post-‐Seismic Uplift Correction (Measured at nearest continuous GPS station) Ucs-‐a = Adjusted Co-‐Seismic Uplift (Ucs-‐a = Ucs-‐m – ΔR – Ups-‐gps)

Field Methods A Pre/Post Earthquake Rapid Coastal Monument Survey (Barometric Altimeter) B Pre/Post Earthquake Beach Profile Survey (Hand Level & Stadia Rod) C Pre/Post Earthquake High Tide Debris Line Survey (Hand Level & Stadia Rod) D Displaced High Tide Notches & Rock Staining (Stadia Rod) E Vertical Extent of Mortality for Sessile Intertidal Organisms (Stadia Rod) F Depth of Stream Incision & Mangrove Root Exposure (Stadia Rod)





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Table S2: Geomorphic uplift results shown in Figure 2 and S1.

Ucs-‐m ΔR Ups-‐gps Ucs-‐a # Location Measured Wave Run-‐Up Post-‐Seismic Adjusted RSS Field Site Site

Uplift Correction Correction Uplift Error Method Latitude Longitude (m) (m) (m) (m) (± m) (deg N) (deg W) 1 Playa Langosta (Tamarindo) 0.00 n/a n/a 0.00 0.20 A,B 10.2873 -‐85.8516 2 Playa Avellanas (Avellanas) 0.28 -‐0.04 -‐0.02 0.22 0.20 A,B,C 10.2288 -‐85.8376 3 Playa Callejones (Pochotes) 0.42 -‐0.06 -‐0.02 0.34 0.20 B,C,F 10.1851 -‐85.8239 4 Playa Junquillal (Iguanazul) 0.40 n/a -‐0.02 0.38 0.10 A,E 10.1754 -‐85.8175 5 Playa Cocal (San Juanillo) 0.72 -‐0.11 -‐0.02 0.59 0.20 B,C 10.0314 -‐85.7416 6 Playa Peladas (Nosara) 0.66 -‐0.10 -‐0.03 0.53 0.20 A,C 9.9537 -‐85.6753 7 Playa Guiones Sur

(Punta Guiones) 0.80 -‐0.12 -‐0.03 0.65 0.20 A,B,C 9.9221 -‐85.6608

8 Playa Garza Oeste (Punta Guiones)

0.76 -‐0.11 -‐0.03 0.62 0.20 B,C 9.9075 -‐85.6509

9 Playa Sámara Oeste (Sámara)

0.72 -‐0.11 -‐0.05 0.56 0.20 C 9.8772 -‐85.5331

10 Playa Sámara Este (Punta Indio)

0.73 -‐0.11 -‐0.05 0.57 0.20 C 9.8683 -‐85.5072

11 Playa Carrillo Oeste (Punta Indio)

0.72 -‐0.11 -‐0.05 0.56 0.20 C,F 9.8692 -‐85.4991

12 Playa Carrillo Este (Puerto Carrillo)

0.85 -‐0.13 -‐0.05 0.67 0.20 A,B,C,G 9.8663 -‐85.4828

13 Playa Bejuco (Bejuco) 0.55 n/a -‐0.03 0.52 0.10 E 9.8181 -‐85.3329 14 Playa Caletas

(Punta Coyote) 0.46 -‐0.07 -‐0.03 0.36 0.20 A,B,C 9.7595 -‐85.2692

15 Playa Carmen (Malpaís) 0.00 n/a n/a 0.00 0.20 C 9.6267 85.1522

Explanation Ucs-‐m = Measured Co-‐Seismic Uplift (Tide corrected) ΔR = Wave Run-‐Up Correction (ΔR = Rpre-‐EQ -‐ Rpost-‐EQ)

Ups-‐gps = Post-‐Seismic Uplift Correction (Measured at nearest continuous GPS station) Ucs-‐a = Adjusted Co-‐Seismic Uplift (Ucs-‐a = Ucs-‐m – ΔR – Ups-‐gps)

Field Methods A Pre/Post Earthquake Rapid Coastal Monument Survey (Barometric Altimeter) B Pre/Post Earthquake Beach Profile Survey (Hand Level & Stadia Rod) C Pre/Post Earthquake High Tide Debris Line Survey (Hand Level & Stadia Rod) D Displaced High Tide Notches & Rock Staining (Stadia Rod) E Vertical Extent of Mortality for Sessile Intertidal Organisms (Stadia Rod) F Depth of Stream Incision & Mangrove Root Exposure (Stadia Rod)

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Figure S1: Comparison of vertical uplift as measured by coastal continuous and campaign GPS site (green and orange) and as determined by geomorphic field observations. The spatial extent and amplitude of the geomorphic results largely agrees with those determined using GPS data, though with substantially greater error. This result highlights the utility of rapid geomorphic studies for the evaluation of coseismic deformation, particularly when pre-existing GPS measurements are not available. The same data are shown in Figure 2b and are repeated here without inland data for visual clarity.

−86˚ −85.5˚ −85˚9.5˚

10˚

10.5˚

50 km

Playa L

ango

sta

Playa A

vellan

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Playa C

allejon

es

Playa J

unqu

illal

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ocal

Playa P

elada

s

Playa G

uione

s

Playa G

arza

Playa S

amara

Playa C

arrillo

Playa B

ejuco

Playa C

aletas

Playa C

armen

20 cm

Campaign GPS

Continuous GPS

Geomorphic





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Figure S2: Checkerboard test on the spatial resolution of the dense Nicoya GPS network. (a) Synthetic input slip distribution; (b) Inverted best fit slip distribution at = 1; and (c) best-fit slip distribution at = 18,000. The green line outlines the best-resolved region, comparable to the area found in Feng et al., [2012]. The red vectors show the orientation and magnitude of input and predicted slip. The red diamonds and yellow circles are the campaign and continuous sites, respectively.

−86˚

−86˚

−85.5˚

−85˚

9˚

9˚

9.5˚

9.5˚

10˚ 0 25 50 75 100 125

Campaign SitesContinuous Sites1 m Slip

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a

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9˚ 9.5˚

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0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0Coseismic Slip [m]

Distance to Trench [km]

b

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c





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Figure S3: The best-fit coseismic slip distribution for the 5 September 2012 Nicoya earthquake at different smoothing levels: (a) = 5000, (b) = 18,000, and (c) = 40,000. As smoothing increases, slip becomes more distributed, but more poorly match the data. (d) A trade-off curve between decreased roughness and increased misfit, represent as reduced chi-square. Our preferred model at = 18,000 is chosen in near the inflection-point of the curve.





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Supplementary References:

1. DeShon, H. R. et al. Seismogenic zone structure beneath the Nicoya Peninsula, Costa Rica, from 3D local earthquake P and S wave tomography. Geophys. J. Int. 164, 109–124, (2006).

2. Thurber, C. H. Local earthquake tomography: velocities and vp /vs theory, in: Seismic Tomography: Theory and Practice. eds. H. M. lyer and K. Hirahara, Chapman and Hall, London, 563-583, (1993).

3. Bertiger, W. et al. Single receiver phase ambiguity resolution with GPS data. J. Geodesy, 84(5), 327-337, (2010).

4. Zumberge, J. F., Heflin, M. B., Jefferson, D. C. ,Watkins, M. M. & Webb, F. H. Precise point positioning for the efficient and robust analysis of GPS data from large networks. J. Geophys. Res. 102(B3), 5005-5017, (1997).

5. Desai, S.D. et al. Results from the Reanalysis of Global GPS Data in the IGS08 Reference Frame. Trans. Amer. Geophys. Union, G53B-0904 [abstract], (2011).

6. Feng, L. et al. Active deformation near the Nicoya Peninsula, northwestern Costa Rica, between 1996 and 2010: Interseismic megathrust coupling. J. Geophys. Res. 117(B6), B06407. (2012).

7. Press, W. H., Teukolsky, S. A., Vetterling, W. T. & Flannery, B. P. Numerical Recipes in FORTRAN. Cambridge University Press, Cambridge, MA, 964 pp., (1992).

8. Bodin, P. & Klinger, T. Coastal uplift and mortality of intertidal organisms caused by the September, 1985 Mexico earthquake. Science 233, 1071–1073, (1986).

9. Carver, G.A., Jayke, A.S., Valentine, D.W. & Li, W.H. Coastal uplift associated with the 1992 Cape Mendocino earthquake, northern California. Geology, 22, 195–198 (1994).

10. Rajendran, C. P. et al. Crustal deformation and seismic history associated with the 2004 Indian Ocean earthquake: A perspective from the Andaman–Nicobar Islands. Bull. Seismol. Soc. Amer. 97, 174-191, (2007).

11. Flater, D. A brief introduction to XTide. Linux Journal 32, 51-57 (1996). 12. Gill, S.K., & Schultz, J.R. Tidal datums and their applications. NOAA Special

Publication NOS CO-OPS 1, U.S. Department of Commerce, National Ocean Service, Center for Operational Oceanographic Products and Services, Silver Springs, Maryland, 112 p., (2001).

13. Pentcheff, D. & Flater, D., WWW Tide/Current Predictor, University of South Carolina, http://tbone.biol.sc.edu/tide/index.html (Accessed September 5, 2012).

14. Nielsen, P. and Hanslow, D.J., 1991, Wave runup distributions on natural beaches, Journal of Coastal Research, v. 7, no. 4, p. 1139-1152, (1991).





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Nicoya earthquake rupture anticipated by geodetic ......Supplementary Text for “Nicoya earthquake rupture anticipated by geodetic measurement of the locked plate interface” By: