<div dir="ltr"><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Dear Colleagues,</span></p><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Please join us in Seattle, 23–26 April, 2019 for the SSA Annual Meeting and consider participating in the session entitled "</span><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-weight:700;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Building, Using, and Validating 3D Geophysical Models</span><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">" (description below). Abstracts are due by 11 January, 2019, but if you will be affected by a possible government shutdown, please submit a placeholder for your abstract <b>TODAY</b>. Go to <a href="https://www.seismosoc.org/annual-meeting/" target="_blank">https://www.seismosoc.org/annual-meeting/</a> for additional meeting details.</span></p><br><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Session description:</span></p><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Geophysical models, such as 3-D geologic and seismic velocity models, are needed in three and sometimes four dimensions for a host of applications from predicting earthquake ground motions and crustal deformation to locating natural resources to planning subsurface infrastructure. Many types of observations can be used to inform geophysical models including geologic mapping, borehole data, active and passive seismic imaging, potential field observations, and observations from other direct and indirect methods. Geophysical theory or empirical models may also be used to solve for missing geophysical attributes given other related observations, for example, solving for S-wave velocity and density given the P-wave velocity. Further, some observations sample distinct locations while others average over volumes of varying size, and different methods of informed interpolation and extrapolation may be used to reconcile observations, theory, and empirical relationships into a single geophysical model. We seek contributions in which researchers have developed and/or applied methods for reconciling multiple datasets into a unified geophysical model. Discussion should address the advantages and disadvantages of various types of datasets and methods in an effort to improve and validate the next generation of geophysical models. Applications of geophysical models to improve assessment of hazard and risk, particularly in novel ways or for novel applications, are also encouraged.</span></p><br><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">See you in Seattle!</span></p><br><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Oliver Boyd, USGS Golden (<a href="mailto:olboyd@usgs.gov" target="_blank">olboyd@usgs.gov</a>)</span></p><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Bill Stephenson, USGS Golden (<a href="mailto:wstephens@usgs.gov" target="_blank">wstephens@usgs.gov</a>)</span></p><p dir="ltr" style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0);background-color:transparent;font-variant-numeric:normal;font-variant-east-asian:normal;vertical-align:baseline;white-space:pre-wrap">Brad Aagaard, USGS Menlo Park (<a href="mailto:baagaard@usgs.gov" target="_blank">baagaard@usgs.gov</a>)</span></p></div>