Acknowledging using our iris-related facilities and Data as of December 2016, updated August 2017

Block, K.A., M. Ducea, U. Raye, R.J. Stern, E.Y. Anthony, and K.A. Lehnert (2007), 'A Chemistry-Based Classification for Peridotite Xenoliths', AGU Fall Meeting Abstracts, 33, p. 04

Block, K.A., and K.A. Lehnert (2009), 'Status update on the EarthChem Deep Lithosphere Dataset: a database of mantle xenolith geochemistry', AGU Fall Meeting Abstracts, 51, p. 1676

Block, K.A., K.A. Lehnert, J.D. Walker, A. Fishman, and W.F. McDonough (2006), 'The EarthChem Deep Lithosphere Dataset: Digital access to mantle Xenolith Petrological data', AGU Fall Meeting Abstracts, 43, p. 1647

Block, K.A., R.J. Stern, M.T. Bavoso, and K.A. Lehnert (2008), 'Development of a Uniform Classification Tool for Peridotites Through the use of Geochemical Data From the EarthChem Deep Lithosphere Dataset', EOS Transactions, AGU Fall Meeting Supplement Abstract AN:IN43A-1173, 89(43), p. 1173

Blom, N.A., A. Deuss, H. Paulssen, and L. Waszek (2015), 'Inner core structure behind the PKP core phase triplication', Geophysical Journal International, 201(3), p. 1657-1665 doi: 10.1093/gji/ggv103

Blom, P.S., O. Marcillo, and S.J. Arrowsmith (2015), 'Improved Bayesian Infrasonic Source Localization for regional infrasound', Geophysical Journal International, 203(3), p. 1682-1693 doi: 10.1093/gji/ggv387

Blum, J., H. Igel, and M. Zumberge (2010), 'Observations of Rayleigh-Wave phase velocity and coseismic deformation using an optical fiber, interferometric vertical strainmeter at the SAFOD Borehole, California', Bulletin of the Seismological Society of America, 100(5A), p. 1879-1891 doi: 10.1785/0120090333

Blume, F., and N. Feldl (2005), 'Support of EarthScope GPS Campaigns at the UNAVCO Facility', EOS Transactions, AGU Fall Meeting Abstracts 86(52), p. 1270

Blume, F., C. Meertens, G. Anderson, S. Eriksson, and E. Boyce (2007), 'PBO Nucleus Project Status: Integration of 209 Existing GPS Stations into the Plate Boundary Observatory', AGU Fall Meeting Abstracts, 33, p. 0910

Blume, F., M. Miller, E. Boyce, A. Borsa, and S. Eriksson (2008), 'PBO Nucleus Project Summary: The Successful Integration of 209 Existing GPS Sions in the Plate Boundary Observatory', EOS Transactions, AGU Fall Meeting Supplement Abstract AN:G41B-0628, 89(41), p. 0628

Boaga, J., A. D'Alpaos, G. Cassiani, M. Marani, and M. Putti (2014), 'Plant-soil interactions in salt marsh environments: Experimental evidence from electrical resistivity tomography in the Venice Lagoon', Geophysical Research Letters, 41(17), p. 6160-6166 doi: 10.1002/2014GL060983

Boatwright, J., and T. MacDonald (2011), 'The Variation of Brune Stress Drop with Hypocentral Depth for Moderate (3.4 ≤ M ≤ 5.8) Earthquakes in Northeastern North America', AGU, Fall Meeting 2011, abstract #S21C-08, 21, p. 08

Boatwright, J., and L. Seekins (2011), 'Regional Spectral Analysis of Three Moderate Earthquakes in Northeastern North America', Bulletin of the Seismological Society of America, 101(4), p. 1769-1782 doi: 10.1785/0120100225

Bocin, A., R. Stephenson, A. Tryggvason, I. Panea, V. Mocanu, F. Hauser, and L. Matenco (2005), '2.5D seismic velocity modelling in the south-eastern Romanian Carpathians Orogen and its foreland', Tectonophysics, 410(1-4), p. 273-291

Bock, Y. (2008), 'California Real Time Network: Test Bed for Mitigation of Geological and Atmospheric Hazards within a Modern Data Portal Environment', EOS Transactions, AGU Fall Meeting Supplement Abstract AN:G43A-0642, 89(43), p. 0642

Bock, Y. (2014), 'Real-Time Earthquake Analysis for Disaster Mitigation (READI) Network', AGU Fall Meeting 2014, abstract #G12A-02, 12, p. 02

Bock, Y., D. Melgar, and B. W. Crowell (2011), 'Real-Time Strong-Motion Broadband Displacements from Collocated GPS and Accelerometers', Bulletin of the Seismological Society of America, 101(6), p. 2904-2925 doi: 10.1785/0120110007

Bock, Y., D. Melgar, J. Geng, J.S. Haase, B.W. Crowell, and M.B. Squibb (2013), 'Enhancement of EarthScope Infrastructure with Real Time Seismogeodesy', AGU Fall Meeting 2013, abstract #S21A-2371, 21, p. 2371

Bock, Y., L. Prawirodirdjo, and T.I. Melbourne (2004), 'Detection of arbitrarily large dynamic ground motions with a dense high-rate GPS network', Geophysical Research Letters, 31(6), p. 1-4

Bockholt, B.M., C.A. Langston, H.R. DeShon, S. Horton, and M. Withers (2014), 'Mysterious Tremor‐Like Signals Seen on the Reelfoot Fault, Northern Tennessee', Bulletin of the Seismological Society of America, 104(5), p. 2194-2205 doi: 10.1785/0120140030

Bockholt, B.M., C.A. Langston, and M. Withers (2015), 'Local Magnitude and Anomalous Amplitude Distance Decay in the Eastern Tennessee Seismic Zone', Seismological Research Letters, 86(3), p. 1040-1050 doi: 10.1785/0220140201

Bodin, P., and S. Horton (2004), 'Source Parameters and Tectonic Implications of Aftershocks of the Mw 7.6 Bhuj Earthquake of 26 January 2001', Bulletin of the Seismological Society of America 94(3), p. 818-827

Bodin, P., C.A. Langston, G. Patterson, C. Powell, M. Withers, and J. Gomberg (2005), 'EarthScope Science for Mid-America', EOS Transactions, AGU, 86(7), p. 68

Bodin, P., W.H. Schulz, J.S. Gomberg, J.W. Kean, J.A. Coe, G. Wang, P. MacQueen, K. Foster, and K. Creager (2009), 'The Slumgullion Natural Laboratory: Overview of the 2009 Multidisciplinary Reconnaissance', AGU Fall Meeting Abstracts, 13, p. 1912

Boerner, P., and B. De Pontieu (2013), 'Observations of Transient Structures at a Coronal Hole Boundary with IRIS', AGU Fall Meeting 2013, abstract #SH23B-2113, 23, p. 2113

Boese, C.M., L. Wotherspoon, M. Alvarez, and P. Malin (2015), 'Analysis of Anthropogenic and Natural Noise from Multilevel Borehole Seismometers in an Urban Environment, Auckland, New Zealand', Bulletin of the Seismological Society of America, 105(1), p. 285-299 doi: 10.1785/0120130288

Boettcher, M.S., A. McGarr, and M.J. Johnston (2009), 'Near Source Observations of Earthquake Processes- Seismic Results from the NELSAM Project, South Africa (Invited)', AGU Fall Meeting Abstracts, 21, p. 03

Boettcher, M.S., D.L. Kane, A.F. McGarr, M.J.S. Johnston, and Z. e. Reches (2015), 'Moment Tensors and Other Source Parameters of Mining‐Induced Earthquakes in TauTona Mine, South Africa', Bulletin of the Seismological Society of America, 105(3), p. 1576-1593 doi: 10.1785/0120140300

Bogiatzis, P., and M. Ishii (2015), 'Continuous Wavelet Decomposition Algorithms for Automatic Detection of Compressional‐ and Shear‐Wave Arrival Times', Bulletin of the Seismological Society of America, 105(3), p. 1628-1641 doi: 10.1785/0120140267

Boglatzis, P., I. Altoe, A. Karamitrou, M. Ishii, and H. Ishii (2015), 'DigitSeis: A New Digitization Software and its Application to the Harvard-Adam Dziewoński Observatory Collection', AGU Fall Meeting 2015, abstract #S33C-2791, p.

Boettcher, M.S., and J.J. McGuire (2009), 'Scaling relations for seismic cycles on mid-ocean ridge transform faults', Geophysical Research Letters, 36, p. 1-1 - 1-5 doi: 10.1029/2009GL040115

Bogiatzis, P., and M. Ishii (2014), 'Constraints on the Moment Tensor of the 2011 Tohoku‐Oki Earthquake from Earth’s Free Oscillations', Bulletin of the Seismological Society of America, 104(2), p. 875-884 doi: 10.1785/0120130243

Bohon, W., S. Robinson, R. Arrowsmith, and S. Semken (2013), 'Building an Effective Social Media Strategy for Science Programs', Eos, Transactions American Geophysical Union, 94(27), p. 237-238 doi: 10.1002/2013EO270001

Bohon, W., S. Robinson, R. Arrowsmith, and S.C. Semken (2013), 'Social Media and Science: where do we go from here?' AGU Fall Meeting 2013, abstract #PA31B-1832, 31, p. 1832

Bökelmann, G.H.R. (1992), Upper and lower mantle small-scale heterogeneity studied by systematic analysis of portable broadband waveforms and traveltimes, Ph.D. Thesis thesis, 198pp. pp, Princeton University/ Carnegie Institution

Bökelmann, G.H.R., and P.G. Silver (1991), A procedure for the extraction of multiple body wave traveltimes from seismological waveform data, in Proceedings of the CP90 Europhysics Conference on Computational Physics, edited by A. Tenner, Worlds Scientific Publishing Co

Bökelmann, G.H.R., and P.G. Silver (1993), 'The Caribbean Anomaly: Short-wavelength lateral heterogeneity in the lower mantle from portable teleseismic data', Geophysical Research Letters, 20(12), p. 1131-1134

Bökelmann, G.H.R., and A. Wüstefeld (2009), 'Comparing crustal and mantle fabric from the North American craton using magnetics and seismic anisotropy', Earth and Planetary Science Letters, 277(3-4), p. 355

Boler, F., C. Stolte, J. Riley, J. Davis, L. Estey, and M. Beldyk (2007), 'Global Navigation Satellite Systems Data Handling, Archiving, Preservation, and Distribution Through the UNAVCO Data Center', AGU Fall Meeting Abstracts, 51, p. 0403

Boler, F.M., C.M. Meertens, C.W. Kreemer, and G. Blewitt (2009), 'Research Enabled through Eighteen Years of Geodesy Data Sharing by the UNAVCO Data Center', AGU Fall Meeting Abstracts, 51, p. 0023

Boles, J.R., G. Garven, H. Camacho, and J.E. Lupton (2015), 'Mantle helium along the Newport-Inglewood fault zone, Los Angeles basin, California: A leaking paleo-subduction zone', Geochemistry Geophysics Geosystems, 16(7), p. 2364-2381 doi: 10.1002/2015gc005951

Bolhar, R., B.S. Kamber, S. Moorbath, C.M. Fedo, and M.J. Whitehouse (2004), 'Characterisation of early Archaean chemical sediments by trace element signatures', Earth and Planetary Science Letters, 222(1), p. 43-60

Bollmann, T.A., S. van der Lee, and A.W. Frederiksen (2013), 'Preliminary Results of P & S-wave Teleseismic Tomography of the Superior Region', AGU Fall Meeting 2013, abstract #T23B-2578, 23, p. 2578

Bollmann, T.A. (2014), 'The Crust and Mantle Structure of the Mid-Continent Rift System from Ambient Noise and Earthquake Surface Wave Analysis', AGU Fall Meeting 2014, abstract #T23B-4656, 23, p. 4656

Bollmann, T.A., S. van der Lee, A.W. Frederiksen, E. Wolin, G.I. Aleqabi, J. Revenaugh, D.A. Wiens, and F.A. Darbyshire (2014), 'Teleseismic P-wave Delay Time Tomography of the southern Superior Province and Midcontinent Rift System (MRS) Region', AGU Fall Meeting 2014, abstract #S13B-4455, 13, p. 4455

Bolton, H., and G. Masters (2001), 'Travel times of P and S from the global digital seismic networks: Implications for the relative variation of P and S velocity in the mantle', Journal of Geophysical Research, 106(B7), p. 13527-13540

Bolton, H.F., R. Buland, L. Gee, J. Mayer, V. Peyton, L. Sandoval, and T. Storm (2006), 'Quality control of the USGS broadband seismic networks', AGU Fall Meeting Abstracts, 11, p. 0197

Bolton, H.F., C.R. Hutt, G. Slad, R.L. Woodward, and R. Butler (1998), 'Timing problems in the Global Seismographic Network', EOS Transaction, AGU, 79(Suppl.), p. F628

Bonaime, S., E. Stutzmann, A. Maggi, M. Vallée, and C. Pardo (2013), 'The GEOSCOPE network', AGU Fall Meeting 2013, abstract #S51A-2289, 51, p. 2289

Bonamassa, O., and J.E. Vidale (1991), 'Directional site resonances observed from aftershocks of the 18 October 1989 Loma Prieta earthquake', Bulletin of the Seismological Society of America, 81(5), p. 1945-1957

Bonamassa, O., J. E. Vidale, H. Houston, and S. Y. Schwartz (1991), 'Directional site resonances and the strong influence of near-surface geology on ground motion', Geophysical Research Letters, 18, p. 901-904

Bonatto, L., M. Schimmel, J. Gallart, and J. Morales (2013), 'Studying the 410-km and 660-km discontinuities beneath Spain and Morocco through detection of P-to-s conversions', Geophysical Journal International, 194(2), p. 920-935 doi: 10.1093/gji/ggt129

Bonatto, L., M. Schimmel, J. Gallart, and J. Morales (2015), 'The upper-mantle transition zone beneath the Ibero-Maghrebian region as seen by teleseismic Pds phases', Tectonophysics, 663, p. 212-224 doi: 10.1016/j.tecto.2015.02.002

Bondar, I., and R. North (1999), 'Development of calibration techniques for the CTBT International Monitoring System', Physics of the Earth and Planetary Interiors, 113, p. 11-24

Bondar, I., R.G. North, and G. Beall (1999), 'Teleseismic slowness-azimuth station corrections for the International Monitoring System Seismic Network', Bulletin of the Seismological Society of America, 89, p. 989-1003

Bondár, I., and D. Storchak (2011), 'Improved location procedures at the International Seismological Centre', Geophysical Journal International, 186(3), p. 1220-1244 doi: 10.1111/j.1365-246X.2011.05107.x

Boniface, K., K.M. Larson, E.E. Small, F.G. Nievinski, and J.J. Braun (2012), 'PBO-H2O: GPS Sensing of Snow Depth in the Western United States', AGU 2012 Fall Meeting, abstract #C33A-0636 Poster, p

Bonner, J., R. Herrmann, and H. Benz (2010), 'Variable-Period surface-wave magnitudes: A rapid and robust estimator of seismic moments', Bulletin of the Seismological Society of America, 100(5A), p. 2301-2309 doi: 10.1785/0120090388

Bonner, J., R.B. Herrmann, D. Harkrider, and M. Pasyanos (2008), 'The Surface Wave Magnitude for the 9 October 2006 North Korean Nuclear Explosion', Bulletin of the Seismological Society of America, 98(5), p. 2498-2506 doi: 10.1785/0120080929

Bonner, J., and D.R. Russell (2013), 'MRg: A Magnitude Scale for 1s Rayleigh Waves at Local Distances with Focus on Yield Estimation', Bulletin of the Seismological Society of America, 103(5), p. 2898-2905 doi: 10.1785/0120130067

Bonner, J.L., M.R. Leidig, C. Sammis, and R.J. Martin (2009), 'Explosion coupling in frozen and unfrozen rock: Experimental data collection and analysis', Bulletin of the Seismological Society of America, 99(2A), p. 830-851 doi: 10.1785/0120080259

Bonner, J.L., and D.R. Russell (2012), 'Effects of Delay Firing on Surface Waves', Bulletin of the Seismological Society of America, 102(5), p. 2209-2218 doi: 10.1785/0120120081

Bonner, J.L., D.R. Russell, D.G. Harkrider, D.T. Reiter, and R.B. Herrmann (2006), 'Development of a time-domain, variable-period surface-wave magnitude measurement procedure for application at regional and teleseismic distances, Part II: Application and Ms-mb performance', Bulletin of the Seismological Society of America 96(2), p. 678-696

Bonner, J.L., D.R. Russell, and R.E. Reinke (2013), 'Modeling Surface Waves from Aboveground and Underground Explosions in Alluvium and Limestone', Bulletin of the Seismological Society of America, 103(6), p. 2953-2970 doi: 10.1785/0120130069

Bonner, J.L., A. Stroujkova, and D. Anderson (2011), 'Determination of Love- and Rayleigh-Wave Magnitudes for Earthquakes and Explosions', Bulletin of the Seismological Society of America, 101(6), p. 3096-3104 doi: 10.1785/0120110131

Bonnin, M., G. Barruol, and G. Bökelmann (2009), 'SKS Splitting and Upper Mantle Geodynamics Under California', AGU Fall Meeting Abstracts, 11, p. 1684

Bonnin, M., G. Barruol, and G.H.R. Bökelmann (2010), 'Upper mantle deformation beneath the North American - Pacific plate boundary in California from SKS splitting', Journal of Geophysical Research, 115(B04306), p. 17 doi: 10.1029/2009JB006438

Bonnin, M., A. Tommasi, R. Hassani, S. Chevrot, J. Wookey, and G. Barruol (2012), 'Numerical modelling of the upper-mantle anisotropy beneath a migrating strike-slip plate boundary: the San Andreas Fault system', Geophysical Journal International, 191(2), p. 436-458 doi: 10.1111/j.1365-246X.2012.05650

Booker, J. (2014), 'The Magnetotelluric Phase Tensor: A Critical Review', Surveys in Geophysics, 35(1), p. 7-40 doi: 10.1007/s10712-013-9234-2

Boomer, K.B., R.A. Brazier, and A.A. Nyblade (2010), 'Empiricallybased ground truth criteria for seismic events recorded at local distances on Regional Networks with Application to Southern Africa', Bulletin of the Seismological Society of America, 100(4), p. 1785-1791 doi: 10.1785/0120090237

Boomer, K.B., R.A. Brazier, J.P. O’Donnell, A.A. Nyblade, J. Kokoska, and S. Liu (2013), 'From Craton to Rift: Empirically Based Ground‐Truth Criteria for Local Events Recorded on Regional Networks', Bulletin of the Seismological Society of America, 103(4), p. 2295-2304 doi: 10.1785/0120120276

Boonen, J., and S. Lebedev (2005), 'Anisotropic seismic structure beneath cratons from interstation surface-wave dispersion measurements on GSN and Geofon Data', EOS Transaction, AGU Fall Meeting Abstracts 86(52), p. 0439

Boore, D.M., and M.W. Asten (2008), 'Comparisons of Shear-Wave Slowness in the Santa Clara Valley, California, Using Blind Interpretations of Data from Invasive and Noninvasive Methods', Bulletin of the Seismological Society of America, 98(4), p. 1983-2003 doi: 10.1785/0120070277

Booth, C.M., D.W. Forsyth, and D.S. Weeraratne (2014), 'Upper mantle Q structure beneath old seafloor in the western Pacific', Journal of Geophysical Research: Solid Earth, 119(4), p. 3448-3461 doi: 10.1002/2013JB010589

Bordet, E., M.G. Mihalynuk, C.J.R. Hart, J.K. Mortensen, R.M. Friedman, and J. Gabites (2013), 'Chronostratigraphy of Eocene volcanism, central British Columbia1', Canadian Journal of Earth Sciences, 51(1), p. 56-103 doi: 10.1139/cjes-2013-0073

Bordet, E., M.G. Mihalynuk, C.J.R. Hart, J.K. Mortensen, R.M. Friedman, and J. Gabites (2014), 'Chronostratigraphy of Eocene volcanism, central British Columbia', Canadian Journal of Earth Sciences, 51(1), p. 56-103 doi: 10.1139/cjes-2013-0073

Bordoni, P., G. Di Giulio, A.J. Haines, F. Cara, G. Milana, and A. Rovelli (2010), 'Issues in choosing the references to use for Spectral Ratios from observations and modeling at Cavola Landslide in Northern Italy', Bulletin of the Seismological Society of America, 100(4), p. 1578-1613 doi: 10.1785/0120090116

Borges, J.F., M. Bezzeghoud, E. Buforn, C. Pro, and A. Fitas (2007), 'The 1980, 1997 and 1998 Azores earthquakes and some seismo-tectonic implications', Tectonophysics, 435(1), p. 37

Borisova, A.Y., C. Martel, S. Gouy, I. Pratomo, S. Sumarti, J.-P. Toutain, I. N. Bindeman, P. de Parseval, J.-P. Metaxian, and Surono (2013), 'Highly explosive 2010 Merapi eruption: Evidence for shallow-level crustal assimilation and hybrid fluid', Journal of Volcanology and Geothermal Research, 261(0), p. 193-208 doi: 10.1016/j.jvolgeores.2012.11.002

Borisova, A.Y., J.-P. Toutain, A. Stefansson, S. Gouy, and P. de Parseval (2012), 'Processes controlling the 2010 Eyjafjallajökull explosive eruption', Journal of Geophysical Research: Solid Earth, 117(B5), p. n/a doi: 10.1029/2012JB009213

Bormann, J.M., W.C. Hammond, C.W. Kreemer, and G. Blewitt (2012), 'Active deformation in the Northern Walker Lane: a detailed geodetic study of the Mohawk Valley and Honey Lake/Warm Springs fault systems', AGU 2012 Fall Meeting, abstract #G22B-03, p

Bormann, J.M., W.C. Hammond, C.W. Kreemer, G. Blewitt, and S.G. Wesnousky (2009), 'GPS constraints on shear accommodation in the northern Walker Lane, western Nevada, USA', AGU Fall Meeting Abstracts, 33, p. 0651

Bormann, J.M., B.E. Surpless, M.W. Caffee, and S.G. Wesnousky (2012), 'Holocene Earthquakes and Late Pleistocene Slip-Rate Estimates on the Wassuk Range Fault Zone, Nevada', Bulletin of the Seismological Society of America, 102(4), p. 1884-1891 doi: 10.1785/0120110287

Bormann, P. (2000), 'International training courses on seismology and seismic risk assessment for developing countries', Seismological Research Letters, 71, p. 499-509

Bormann, P., and E. Bergman (2000), 'The new IASPEI manual of seismological observatory practice', Seismological Research Letters, 71, p. 510-518

Bormann, P., and J. Saul (2008), 'The New IASPEI Standard Broadband Magnitude mB', Seismological Research Letters, 79(5), p. 698-705 doi: 10.1785/gssrl.79.5.698

Bormann, P., and J. Saul (2009), 'A Fast, Non-saturating magnitude estimator for Great Earthquakes', Seismological Research Letters, 80(1), p. 128-133 10.1785/gssrl.80.5.808

Borrero, J.C., J. Bu, C. Saiang, B. Uslu, J. Freckman, B. Gomer, E.A. Okal, and C.E. Synolakis (2003), 'Field survey and preliminary modeling of the Wevak, Papua New Guinea earthquake and Tsunami of 9 September 2002', Seismological Research Letters 74(4), p. 393-405

Borsa, A., and J.B. Minster (2012), 'Rapid Determination of Near-Fault Earthquake Deformation Using Differential LiDAR', Bulletin of the Seismological Society of America, 102(4), p. 1335-1347 doi: 10.1785/0120110159

Borsa, A.A., and D.C. Agnew (2014), 'Drought-induced stress changes on faults associated with the 2014 South Napa earthquake', AGU Fall Meeting 2014, abstract #S44D-05, 44, p. 05

Borsa, A.A., D.C. Agnew, and D.R. Cayan (2014), 'Ongoing drought-induced uplift in the western United States', Science, 345 no. 6204, p. 1587-1590 doi: 10.1126/science.1260279

Borsa, A.A., M. Jackson, K. Feaux, D. Mencin, S. Smith, J. Smith, D. Torres, and L. Snett (2008), 'Real time data from the Plate Boundary Observatory continuous GPS network', EOS Transactions, AGU Fall Meeting Supplement Abstract AN:G43B-08, 89(43), p. 08

Borsa, A.A., C. Meertens, and M. Jackson (2008), 'Noise characteristics of short drilled and deep drilled braced monuments in the PBO continuous GPS network', EOS Transactions, AGU Fall Meeting Supplement Abstract AN: G41B-0626 INVITED 89(41), p. 0626

Bos, A.G., G. Nolet, A. Rubin, H. Houston, and J.E. Vidale (1998), 'Duration of deep earthquakes determined by stacking of Global Seismograph Network seismograms', Journal of Geophysical Research, 103(9), p. 21059-21065

Boschi, L., and C. Weemstra