Drew Siler is a Research Geologist at the Geology, Minerals, Energy, and Geophysics Science Center. He received a B.S. in Earth and Space Science from University of Washington in 2005 and a Ph.D. in Geology from Syracuse University in 2011. Presently, his research focuses on understanding the role of fault systems as conduits for geothermal circulation.
Dr. Drew Siler has devoted his career to structural geology and tectonics and specializes in Geothermal Systems.
His past research focused on magmatic rifts, mid-ocean ridges, and ophiolite complexes, applying geologic mapping and structural analysis in order to characterize volcanic construction and tectonic deformation processes in magmatic rifts and mid-ocean ridge systems.
Drew's current research is focused characterizing geologic systems in 3-dimensions. This includes geologic mapping and working with a wide variety of data sets including drill cuttings and core, subsurface temperature data, seismic reflection data, potential-field geophysical data, diffuse degassing measurements along faults, helium isotope data, 3D geologic mapping, structural analyses, and machine learning. His research applies these tools and techniques to evaluate permeability distribution in fault systems in 3D and characterizing the geologic controls of fluid flow in geothermal systems.
Professional Experience
2020-Present, Research Geologist, Geology, Minerals, Energy, and Geophysics Science Center, U.S. Geological Survey, Moffett Field, CA
2016-Present, Research Affiliate, Lawrence Berkeley National Laboratory, Berkeley, CA
2016-2020, Research Geologist and Mendenhall Fellow, Geology, Minerals, Energy, and Geophysics Science Center, U.S. Geological Survey, Menlo Park, CA
2013-2016, Post-Doctoral Fellow, Lawrence Berkeley National Laboratory, Berkeley, CA
2011-2013, Post-Doctoral Fellow, Nevada Bureau of Mines and Geology, University of Nevada, Reno
2011 Post Doctoral Fellow, Syracuse University, Syracuse, NY
Education and Certifications
Ph.D., Geology, Syracuse University, 2011
B.Sc., Earth and Space Sciences, University of Washington, 2005
Affiliations and Memberships
2011-Present, Geothermal Resources Council
2006-Present, American Geophysical Union
2006-Present, Geological Society of America
Lawrence Berkeley National Lab
National Renewable Energy Lab
Los Alamos National Lab
Utah State University
Colorado School of Mines
University of Nevada, Reno
Boise State University
Nevada Bureau of Mines and Geology
Sandia National Lab
U.S. Navy Geothermal Program Office
Itasca Consulting Group
Innovate Geothermal
Ormat Technologies
Science and Products
Three-dimensional geologic map of the Brady geothermal area, Nevada
The three-dimensional (3D) geologic map characterizes the subsurface in the Brady geothermal area in the northern Hot Springs Mountains of northwestern Nevada. We built the 3D map by integrating the results from detailed geologic mapping, seismic-reflection, potential-field-geophysical, and lithologic well-logging investigations completed in the study area. This effort was undertaken to investigat
Three-dimensional geologic map of the southern Carson Sink, Nevada, including the Fallon FORGE area
The three-dimensional (3–D) geologic map characterizes the subsurface in the southern Carson Sink region. We created the 3–D map by integrating the results from seismic-reflection, potential-field-geophysical, and lithologic well-logging investigations completed in and around the Fallon FORGE site as part of the U.S. Department of Energy Frontier Observatory for Research in Geothermal Energy (FOR
Filter Total Items: 17
Machine learning to identify geologic factors associated with production in geothermal fields: A case-study using 3D geologic data, Brady geothermal field, Nevada
In this paper, we present an analysis using unsupervised machine learning (ML) to identify the key geologic factors that contribute to the geothermal production in Brady geothermal field. Brady is a hydrothermal system in northwestern Nevada that supports both electricity production and direct use of hydrothermal fluids. Transmissive fluid-flow pathways are relatively rare in the subsurface, but a
Stochastic inversion of gravity, magnetic, tracer, lithology, and fault data for geologically realistic structural models: Patua Geothermal Field case study
Financial risk due to geological uncertainty is a major barrier for geothermal development. Production from a geothermal well depends on the unknown location of subsurface geological structures, such as faults that contain hydrothermal fluids. Traditionally, geoscientists collect many different datasets, interpret the datasets manually, and create a single model estimating faults' locations. This
3-D geologic controls of hydrothermal fluid flow at Brady geothermal field, Nevada, USA
In many hydrothermal systems, fracture permeability along faults provides pathways for groundwater to transport heat from depth. Faulting generates a range of deformation styles that cross-cut heterogeneous geology, resulting in complex patterns of permeability, porosity, and hydraulic conductivity. Vertical connectivity (a throughgoing network of permeable areas that allows advection of heat from
Geothermal play fairway analysis of the Sou Hills, northern Nevada: A major quaternary accommodation zone in the Great Basin region
To facilitate discovery and development of blind geothermal systems in the Great Basin region, as well as assessment of known systems with surface hot springs, a play fairway approach was developed to evaluate and integrate multiple geologic and geophysical parameters for permeability and heat. Phase 1 of the project produced a geothermal potential map of 96,000 km2 of Nevada. This analysis yielde
Subsurface characterization and machine learning predictions at Brady Hot Springs
Subsurface data analysis, reservoir modeling, and machine learning (ML) techniques have been applied to the Brady Hot Springs (BHS) geothermal field in Nevada, USA to further characterize the subsurface and assist with optimizing reservoir management. Hundreds of reservoir simulations have been conducted in TETRAD-G and CMG STARS to explore different injection and production fluid flow rates and a
Play fairway analysis in geothermal exploration: The Snake River plain volcanic province
The Snake River volcanic province (SRP) has long been considered a target for geothermal development. It overlies a thermal anomaly that extends deep into the mantle and represents one of the highest heat flow provinces in North America, but systematic exploration been hindered by lack of a conceptual model. Play Fairway Analysis (PFA) is a methodology adapted from the petroleum industry that inte
Can geologic factors be predictive for distinguishing between productive and non-productive geothermal wells?
Geologic data are examined to evaluate whether certain geologic characteristics occur in higher abundance or higher magnitude along production geothermal wells relative to non-productive wells. We perform 3D geologic mapping, 3D stress modeling, and fault-slip modeling to estimate fourteen different geologic factors that are hypothesized to control or correlate with well productivity. The geologic
Discovering blind geothermal systems in the Great Basin Region: An integrated geologic and geophysical approach for establishing geothermal play fairways: All phases
Most geothermal resources in the Great Basin region of the western USA are blind, and thus the discovery of new commercial-grade systems requires synthesis of favorable characteristics for geothermal activity. The geothermal play fairway concept involves integration of multiple parameters indicative of geothermal activity to identify promising areas for new development. This project integrated mul
Uncertainty and risk evaluation during the exploration stage of geothermal development
Quantifying and representing uncertainty for geothermal systems is often ignored, in practice, during the exploration phase of a geothermal development project. We propose that this occurs potentially because the task seems so formidable. The primary goal of this paper is to initiate a dialogue within the geothermal community about: which geothermal uncertainties should receive the most attention
Integrating magnetotellurics, soil gas geochemistry and structural analysis to identify hidden, high enthalpy, extensional geothermal systems
We applied magnetotellurics (MT), diagnostic structural affiliations, soil gas flux, and fluid geochemistry to assist in identifying hidden, high-enthalpy geothermal systems in extensional regimes of the U.S. Great Basin. We are specifically looking for high-angle, low-resistivity zones and dilatant geologic structures that can carry fluids from magmatic or high-grade metamorphic conditions in the
Three-dimensional geologic mapping to assess geothermal potential: Examples from Nevada and Oregon
Geologic structure plays an important role in controlling fluid flow in geothermal systems. In particular, very complex structural settings, consisting of many closely spaced and intersecting faults, host many geothermal systems. To elucidate the key geologic factors that affect fault-controlled geothermal circulation, it is critical to precisely characterize the structural and stratigraphic geome
Uncertainty and risk evaluation during the exploration stage of geothermal development: A review
Quantifying and representing uncertainty for geothermal systems is often ignored, in practice, during the exploration phase of a geothermal development project. We propose that this occurs potentially because the task seems so formidable. The primary goal of this paper is to initiate a dialogue within the geothermal community about: which geothermal uncertainties should receive the most attention
Pre-USGS Publications
Siler, D.L., and Karson, J.A., 2017. Along-Axis Structure and Crustal Construction Processes of Spreading Segments in Iceland: Implications for Magamatic Rifts. Tectonics.
Siler, D.L., Yingqi Zhang, Nicolas F. Spycher, Patrick F. Dobson, James S. McClain, Erika Gasperikova Robert A. Zierenberg, Peter Schiffman, Colin Ferguson, Andrew Fowler, Carolyn Cantwell, 2017. Play-fairway analysis for geothermal resources and exploration risk in the Modoc Plateau region, Geothermics. 69, 15-33.
Siler, D.L., and Kennedy, B.M., 2016. Regional crustal-scale structures as conduits for deep geothermal upflow, Geothermics, 59A, 27-37.
Witter, J.B., Siler, D.L., Faulds, J.E., and Hinz, N.H. 3D geophysical inversion modeling of gravity data to test the 3D geologic model of the Bradys geothermal area, Nevada, USA.
Witter, J.B., Siler, D.L., Faulds, J.E., and Hinz, N.H. 3D geophysical inversion modeling of gravity data to test the 3D geologic model of the Bradys geothermal area, Nevada, USA.
Witter, J.B., Siler, D.L., Faulds, J.E., and Hinz, N.H. 3D geophysical inversion modeling of gravity data to test the 3D geologic model of the Bradys geothermal area, Nevada, USA.
Siler, D.L., Faulds, J.E. Mayhew, B., and McNamara, D., 2016. Analysis of the favorability for geothermal fluid flow in 3D: Astor Pass geothermal prospect, Great Basin, northwestern Nevada, USA, Geothermics, 60, 1-12.
Siler, D.L., and J.A. Karson, 2012. Sub-volcanic subsidence and caldera formation during sub aerial seafloor spreading in Iceland, Geological Society of America Bulletin, v. 124, no. 7-8, p. 1310-1323.
Siler, D.L., and J.A. Karson, 2009. Three-dimensional structure of inclined sheet swarms: Implications for crustal thickening and subsidence in the volcanic rift zones of Iceland, Journal of Volcanology and Geothermal Research, 188, 333–346
Geophysical characterization of geothermal resources on the Umatilla Indian Reservation in northeast Oregon
During the summers of 2017 and 2020, our team collected gravity, ground magnetic (ATV and hiked traverses), paleomagnetic and rock property (density and susceptibility) data on the Umatilla Indian Reservation (UIR) in northeast Oregon to aid in characterizing subsurface stratigraphy using 2D and 3D modeling methods. This data was integrated with conductance surfaces from a 3D magnetotelluic model
Magnetotelluric Data from the Gabbs Valley Region, Nevada, 2020
This data set consists of 59 wideband magnetotelluric (MT) stations collected by the U.S. Geological Survey in July and August of 2020 as part of a 1-year project funded by the Energy Resources Program of the U.S. Geological Survey to demonstrate full crustal control on geothermal systems in the Great Basin. Each station had 5 components, 3 orthogonal magnetic induction coils and 2 horizontal orth
USGS Contributions to the Nevada Geothermal Machine Learning Project (DE-FOA-0001956): Slip and Dilation Tendency Data
This package contains data in a portion of northern Nevada, the extent of the ?Nevada Machine Learning Project? (DE-EE0008762). Slip tendency (TS) and dilation tendency (TD) were calculated for the all the faults in the Nevada ML study area. TS is the ratio between the shear components of the stress tensor and the normal components of the stress tensor acting on a fault plane. TD is the ratio of a
GIS and Data Tables for Focus Areas for Potential Domestic Nonfuel Sources of Rare Earth Elements
In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.). Acquiring information on possible domestic sources of these critical minerals is the basis of the USGS Earth Mappi
Science and Products
- Maps
Three-dimensional geologic map of the Brady geothermal area, Nevada
The three-dimensional (3D) geologic map characterizes the subsurface in the Brady geothermal area in the northern Hot Springs Mountains of northwestern Nevada. We built the 3D map by integrating the results from detailed geologic mapping, seismic-reflection, potential-field-geophysical, and lithologic well-logging investigations completed in the study area. This effort was undertaken to investigatThree-dimensional geologic map of the southern Carson Sink, Nevada, including the Fallon FORGE area
The three-dimensional (3–D) geologic map characterizes the subsurface in the southern Carson Sink region. We created the 3–D map by integrating the results from seismic-reflection, potential-field-geophysical, and lithologic well-logging investigations completed in and around the Fallon FORGE site as part of the U.S. Department of Energy Frontier Observatory for Research in Geothermal Energy (FOR - Publications
Filter Total Items: 17
Machine learning to identify geologic factors associated with production in geothermal fields: A case-study using 3D geologic data, Brady geothermal field, Nevada
In this paper, we present an analysis using unsupervised machine learning (ML) to identify the key geologic factors that contribute to the geothermal production in Brady geothermal field. Brady is a hydrothermal system in northwestern Nevada that supports both electricity production and direct use of hydrothermal fluids. Transmissive fluid-flow pathways are relatively rare in the subsurface, but aStochastic inversion of gravity, magnetic, tracer, lithology, and fault data for geologically realistic structural models: Patua Geothermal Field case study
Financial risk due to geological uncertainty is a major barrier for geothermal development. Production from a geothermal well depends on the unknown location of subsurface geological structures, such as faults that contain hydrothermal fluids. Traditionally, geoscientists collect many different datasets, interpret the datasets manually, and create a single model estimating faults' locations. This3-D geologic controls of hydrothermal fluid flow at Brady geothermal field, Nevada, USA
In many hydrothermal systems, fracture permeability along faults provides pathways for groundwater to transport heat from depth. Faulting generates a range of deformation styles that cross-cut heterogeneous geology, resulting in complex patterns of permeability, porosity, and hydraulic conductivity. Vertical connectivity (a throughgoing network of permeable areas that allows advection of heat fromGeothermal play fairway analysis of the Sou Hills, northern Nevada: A major quaternary accommodation zone in the Great Basin region
To facilitate discovery and development of blind geothermal systems in the Great Basin region, as well as assessment of known systems with surface hot springs, a play fairway approach was developed to evaluate and integrate multiple geologic and geophysical parameters for permeability and heat. Phase 1 of the project produced a geothermal potential map of 96,000 km2 of Nevada. This analysis yieldeSubsurface characterization and machine learning predictions at Brady Hot Springs
Subsurface data analysis, reservoir modeling, and machine learning (ML) techniques have been applied to the Brady Hot Springs (BHS) geothermal field in Nevada, USA to further characterize the subsurface and assist with optimizing reservoir management. Hundreds of reservoir simulations have been conducted in TETRAD-G and CMG STARS to explore different injection and production fluid flow rates and aPlay fairway analysis in geothermal exploration: The Snake River plain volcanic province
The Snake River volcanic province (SRP) has long been considered a target for geothermal development. It overlies a thermal anomaly that extends deep into the mantle and represents one of the highest heat flow provinces in North America, but systematic exploration been hindered by lack of a conceptual model. Play Fairway Analysis (PFA) is a methodology adapted from the petroleum industry that inteCan geologic factors be predictive for distinguishing between productive and non-productive geothermal wells?
Geologic data are examined to evaluate whether certain geologic characteristics occur in higher abundance or higher magnitude along production geothermal wells relative to non-productive wells. We perform 3D geologic mapping, 3D stress modeling, and fault-slip modeling to estimate fourteen different geologic factors that are hypothesized to control or correlate with well productivity. The geologicDiscovering blind geothermal systems in the Great Basin Region: An integrated geologic and geophysical approach for establishing geothermal play fairways: All phases
Most geothermal resources in the Great Basin region of the western USA are blind, and thus the discovery of new commercial-grade systems requires synthesis of favorable characteristics for geothermal activity. The geothermal play fairway concept involves integration of multiple parameters indicative of geothermal activity to identify promising areas for new development. This project integrated mulUncertainty and risk evaluation during the exploration stage of geothermal development
Quantifying and representing uncertainty for geothermal systems is often ignored, in practice, during the exploration phase of a geothermal development project. We propose that this occurs potentially because the task seems so formidable. The primary goal of this paper is to initiate a dialogue within the geothermal community about: which geothermal uncertainties should receive the most attentionIntegrating magnetotellurics, soil gas geochemistry and structural analysis to identify hidden, high enthalpy, extensional geothermal systems
We applied magnetotellurics (MT), diagnostic structural affiliations, soil gas flux, and fluid geochemistry to assist in identifying hidden, high-enthalpy geothermal systems in extensional regimes of the U.S. Great Basin. We are specifically looking for high-angle, low-resistivity zones and dilatant geologic structures that can carry fluids from magmatic or high-grade metamorphic conditions in theThree-dimensional geologic mapping to assess geothermal potential: Examples from Nevada and Oregon
Geologic structure plays an important role in controlling fluid flow in geothermal systems. In particular, very complex structural settings, consisting of many closely spaced and intersecting faults, host many geothermal systems. To elucidate the key geologic factors that affect fault-controlled geothermal circulation, it is critical to precisely characterize the structural and stratigraphic geomeUncertainty and risk evaluation during the exploration stage of geothermal development: A review
Quantifying and representing uncertainty for geothermal systems is often ignored, in practice, during the exploration phase of a geothermal development project. We propose that this occurs potentially because the task seems so formidable. The primary goal of this paper is to initiate a dialogue within the geothermal community about: which geothermal uncertainties should receive the most attentionPre-USGS Publications
Siler, D.L., and Karson, J.A., 2017. Along-Axis Structure and Crustal Construction Processes of Spreading Segments in Iceland: Implications for Magamatic Rifts. Tectonics.Siler, D.L., Yingqi Zhang, Nicolas F. Spycher, Patrick F. Dobson, James S. McClain, Erika Gasperikova Robert A. Zierenberg, Peter Schiffman, Colin Ferguson, Andrew Fowler, Carolyn Cantwell, 2017. Play-fairway analysis for geothermal resources and exploration risk in the Modoc Plateau region, Geothermics. 69, 15-33.Siler, D.L., and Kennedy, B.M., 2016. Regional crustal-scale structures as conduits for deep geothermal upflow, Geothermics, 59A, 27-37.
Witter, J.B., Siler, D.L., Faulds, J.E., and Hinz, N.H. 3D geophysical inversion modeling of gravity data to test the 3D geologic model of the Bradys geothermal area, Nevada, USA.Witter, J.B., Siler, D.L., Faulds, J.E., and Hinz, N.H. 3D geophysical inversion modeling of gravity data to test the 3D geologic model of the Bradys geothermal area, Nevada, USA.Siler, D.L., Faulds, J.E. Mayhew, B., and McNamara, D., 2016. Analysis of the favorability for geothermal fluid flow in 3D: Astor Pass geothermal prospect, Great Basin, northwestern Nevada, USA, Geothermics, 60, 1-12.Siler, D.L., and J.A. Karson, 2012. Sub-volcanic subsidence and caldera formation during sub aerial seafloor spreading in Iceland, Geological Society of America Bulletin, v. 124, no. 7-8, p. 1310-1323.Siler, D.L., and J.A. Karson, 2009. Three-dimensional structure of inclined sheet swarms: Implications for crustal thickening and subsidence in the volcanic rift zones of Iceland, Journal of Volcanology and Geothermal Research, 188, 333–346 - Data
Geophysical characterization of geothermal resources on the Umatilla Indian Reservation in northeast Oregon
During the summers of 2017 and 2020, our team collected gravity, ground magnetic (ATV and hiked traverses), paleomagnetic and rock property (density and susceptibility) data on the Umatilla Indian Reservation (UIR) in northeast Oregon to aid in characterizing subsurface stratigraphy using 2D and 3D modeling methods. This data was integrated with conductance surfaces from a 3D magnetotelluic modelMagnetotelluric Data from the Gabbs Valley Region, Nevada, 2020
This data set consists of 59 wideband magnetotelluric (MT) stations collected by the U.S. Geological Survey in July and August of 2020 as part of a 1-year project funded by the Energy Resources Program of the U.S. Geological Survey to demonstrate full crustal control on geothermal systems in the Great Basin. Each station had 5 components, 3 orthogonal magnetic induction coils and 2 horizontal orthUSGS Contributions to the Nevada Geothermal Machine Learning Project (DE-FOA-0001956): Slip and Dilation Tendency Data
This package contains data in a portion of northern Nevada, the extent of the ?Nevada Machine Learning Project? (DE-EE0008762). Slip tendency (TS) and dilation tendency (TD) were calculated for the all the faults in the Nevada ML study area. TS is the ratio between the shear components of the stress tensor and the normal components of the stress tensor acting on a fault plane. TD is the ratio of aGIS and Data Tables for Focus Areas for Potential Domestic Nonfuel Sources of Rare Earth Elements
In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.). Acquiring information on possible domestic sources of these critical minerals is the basis of the USGS Earth Mappi