Drew Downs in Iceland with a glacier in hte background.
Drew T. Downs
I am a research geologist with the Hawaiian Volcano Observatory and my main areas of research revolve around constructing geologic maps and unraveling the eruptive histories of volcanoes. To do this, I use a multidisciplinary approach using field studies, physical volcanology, geochronology, geochemistry, petrology, remote sensing, and many more techniques.
I have worked on volcanoes and volcanic fields in a variety of settings, including subduction-related arc volcanoes within New Zealand and the southern Cascades of California, the monogenetic volcanic field of of Harrat Rahat in Saudi Arabia, and unraveling the eruptive history and processes of volcanic rocks of the Hawaiian Islands.
Throughout my research career I have participated in studies on explosive and effusive volcanism ranging from high-silica rhyolites and trachytes to basaltic lava flows. Unraveling the eruptive history preserved at the surface to understanding deeper volcanic processes has led me to use a wide variety of techniques, such as field studies, physical volcanology, geochronology, geochemistry, petrology, paleomagnetism, remote sensing, and other novel methods that help to understand volcanic processes and further understanding of their hazards.
Education and Certifications
2014 - Ph.D., Geology, University of Auckland (New Zealand)
2009 - MSc, Southern Illinois University
2007 - BSc, Southern Illinois University
Science and Products
Sample details and near-real-time ED-XRF data collected during the 2020-2023 Halema‘uma‘u eruptions of Kīlauea volcano, Island of Hawaiʻi
A limited suite of samples for the 2020–2023 Kīlauea eruptions within Kaluapele (the summit caldera) were collected by the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) field teams from within a publicly closed area of Hawai‘i Volcanoes National Park in cooperation with the National Park Service. This data release presents sample metadata, whole rock ED-XRF, whole rock WD...
Whole rock and micro-analytical geochemistry of minerals, melt inclusions, and matrix glasses from Kapoho Crater and Puʻulena Crater, Kīlauea Volcano, Hawaiʻi
Kilauea volcano (Hawaii, USA) is a shield volcano that exhibits both effusive and explosive eruptive activity. Although Kilauea has been predominantly built through effusive eruptions, explosive eruptions have occurred repeatedly at both Kilauea's summit and in the volcano's lower East Rift Zone (Moore, 1992; Swanson et al., 2014). This dataset presents geochemical analyses of samples...
Vesicularity, grain size, and grain shape of basaltic pyroclasts from Kīlauea and Mauna Loa volcanoes, Island of Hawaiʻi
This dataset includes sample information, vesicularity by pycnometer, grain size and shape data by CAMSIZER, and measurements of crushed and thin section mounted grains by microscope. All studied samples were from scoria and air-fall-tephra deposits (most formed in Hawaiian lava fountains) collected around the summits of Mauna Loa and Kīlauea volcanoes, Island of Hawaiʻi. These data were...
Major- and trace-element chemical analyses of whole-rock and glass from the Kamakaiʻa Hills of the Southwest Rift Zone of Kīlauea volcano, Hawaiʻi
This dataset includes wavelength dispersive X-ray fluorescence (WD-XRF) major-oxide and trace-element whole-rock analyses, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) trace-element whole-rock analyses, and glass analyses by electron microprobe of scoria and lava samples from the Kamakaiʻa Hills of the Southwest Rift Zone of Kīlauea volcano, Island of Hawaiʻi...
Colorimeter data for the summit water lake at Kīlauea Volcano, Island of Hawaiʻi, 2020
In 2018, a large effusive eruption on the lower flank of Kīlauea Volcano was associated with collapse and subsidence of the summit caldera floor (Neal and others, 2019). The bottom of Halemaʻumaʻu, a crater nested within the summit caldera, subsided by more than 500 m. In July 2019, water was observed ponding on the deepest part of the Halemaʻumaʻu crater floor and the water rose and...
Sample details and near-real-time ED-XRF, grain size, and grain shape data collected during the November – December 2022 eruption of Mauna Loa volcano, Island of Hawaiʻi
At 11:21 p.m. (Hawaii Standard Time [HST]) on November 27, 2022, Mauna Loa volcano on the Island of Hawaiʻi started erupting from fissures at its summit caldera, Mokuʻāweoweo. This was followed shortly afterwards by the opening of a segment of fissures in the direction of the Southwest Rift Zone. These were mostly within the structural boundary of the caldera, so their location is...
Electron microprobe data for plagioclase, olivine, pyroxene, and spinel in volcanic rocks from the Matan volcanic center located within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
Mineral compositions are reported for Quaternary volcanic rocks of the Matan volcanic center, northern Harrat Rahat, Saudi Arabia. Compositions were measured by wavelength-dispersive methods with the 5-spectrometer JEOL-8900 electron microprobe at the USGS facility in Menlo Park, California; background-corrected X-ray intensities were reduced to oxide weight concentrations with the JEOL...
Water-level data for the crater lake at the summit of Kilauea Volcano, Island of Hawai'i, 2019-2020
During 2018, Kilauea Volcano, on the Island of Hawaiii, had a large effusive eruption (~1 cubic kilometer of lava) on the lower East Rift Zone that caused widespread destruction (Neal and others, 2019; Dietterich and others, 2021). This lower flank eruption was accompanied by one of the largest collapses of the summit caldera in two hundred years, with portions of the caldera floor...
Database for the geologic map of the Paeroa Fault block and surrounding area, Taupo Volcanic Zone, New Zealand
The Taupo Volcanic Zone (TVZ), New Zealand, is the most productive area of explosive silicic volcanism in the world. Faulted early and middle Pleistocene volcanic products are generally concealed beneath voluminous, generally unfaulted, younger volcanic products. An exception is the southeast margin of the TVZ where the two parallel, northeast-trending Paeroa and Te Weta Fault blocks...
Database for the Geologic Map of the Northern Harrat Rahat Volcanic Field, Kingdom of Saudi Arabia
The Harrat Rahat volcanic field, located in the west-central part of the Kingdom of Saudi Arabia, is the largest of 15 harrats (Arabic for 'volcanic field') hosted within the Arabian plate. Harrat Rahat is 50 to 75 km wide (east-west) and 300 km long (north-south), covering an area of approximately 20,000 square kilometers and encompassing more than 900 observable vents. The overall map...
Geologic map of the northern Harrat Rahat volcanic field, Kingdom of Saudi Arabia
Harrat Rahat, in the west-central part of the Kingdom of Saudi Arabia, is the largest of 15 Cenozoic harrats (Arabic for “volcanic field”) distributed on the Arabian plate. It extends more than 300 km north-south and 50 to 75 km east-west, and it covers an area of approximately 20,000 km2, has a volume of approximately 2,000 km3, and encompasses more than 900 observable vents. Volcanism...
Drew Downs in Iceland
Drew Downs in Iceland with a glacier in hte background.
Filter Total Items: 26
Awakening of Maunaloa linked to melt shared from Kilauea’s mantle source
Maunaloa—the largest active volcano on Earth—erupted in 2022 after its longest known repose period (~38 years) and two decades of volcanic unrest. This eruptive hiatus at Maunaloa encompasses most of the ~35-year-long Puʻuʻōʻō eruption of neighboring Kīlauea, which ended in 2018 with a collapse of the summit caldera and an unusually voluminous (~1 km3) rift eruption. A long-term pattern...
Authors
Aaron J. Pietruszka, Daniel E. Heaton, Jared P. Marske, Marc D. Norman, Mahinaokalani G. Robbins, Reed B. Mershon, Kendra J. Lynn, Drew T. Downs, Arron R. Steiner, J. Michael Rhodes, Michael O. Garcia
Triggering the 2022 eruption of Mauna Loa
Distinguishing periods of intermittent unrest from the run-up to eruption is a major challenge at volcanoes around the globe. Comparing multidisciplinary monitoring data with mineral chemistry that records the physical and spatio-temporal evolution of magmas fundamentally advances our ability to forecast eruptions. The recent eruption of Mauna Loa, Earth’s largest active volcano...
Authors
Kendra J. Lynn, Drew T. Downs, Frank A. Trusdell, Penny E. Wieser, Berenise Rangel, Baylee Rose McDade, Alicia J. Hotovec-Ellis, Ninfa Lucia Bennington, Kyle R. Anderson, Dawn Catherine Sweeney Ruth, Charlotte DeVitre, Andria P. Ellis, Patricia A. Nadeau, Laura E. Clor, Peter J. Kelly, Peter Dotray, Jefferson Chang
Depths in a day - A new era of rapid-response Raman-based barometry using fluid inclusions
Rapid-response petrological monitoring is a major advance for volcano observatories, allowing them to build and validate models of plumbing systems that supply eruptions in near-real-time. The depth of magma storage has recently been identified as high-priority information for volcanic observatories, yet this information is not currently obtainable via petrological monitoring methods on...
Authors
Charlotte DeVitre, Penny E. Wieser, Alexander T. Bearden, Araela Richie, Berenise Rangel, Matthew Gleeson, John Grimsich, Kendra J. Lynn, Drew T. Downs, Natalia I. Deligne, Katherine M. Mulliken
Volcanoes of American Samoa
Upu Amata (Introduction)O le Atu-Samoa o le tasi lenei o faʻasologa motu mauga mu i le Vasa Pasefika i Saute. O motu e pito i sasaʻe o nei faʻasologa mauga mu o le Atu-Samoa, o motu ia o Amerika Samoa. E tofu lava mauga mu taʻitasi o Amerika Samoa ma ona talaaga aemaise tulaga e tutupu e ono pa ai i le lumanai. O loʻo galulue faʻatasi le Ofisa o le U.S. Geological Survey (USGS) ma le...
Authors
Natalia I. Deligne, Drew T. Downs, Elinor Lutu-McMoore, Steven Sobieszczyk, Wendy K. Stovall
The influence of vesicularity on grain morphology in basaltic pyroclasts from Mauna Loa and Kīlauea volcanoes
Vesicularity of individual pyroclasts from airfall tephra deposits is an important parameter that is commonly measured at basaltic volcanoes. Conventional methods used to determine pyroclast vesicularity on a large number of clasts has the potential to be time consuming, particularly when rapid analysis is required. Here we propose dynamic image analysis on two-dimensional (2D)...
Authors
Kira van Helden, Johanne Schmith, Drew T. Downs
Origins and nature of large explosive eruptions in the lower East Rift Zone of Kīlauea volcano, Hawaii: Insights from ash characterization and geochemistry
Several powerful explosive eruptions have taken place in the populated lower East Rift Zone of Kīlauea within the past ∼750 years. These have created distinctive landforms, including a tephra rim enclosing Puʻulena Crater immediately south of the Puna Geothermal Venture power station, a tuff cone at Kapoho Crater near the eastern cape of the Island of Hawaiʻi, and a set of littoral cones...
Authors
Richard W. Hazlett, Johanne Schmith, Allan Lerner, Drew T. Downs, Erin P. Fitch, Carolyn E. Parcheta, Cheryl A. Gansecki, Sarah Spaulding
Tracking magma pathways and surface faulting in the Southwest Rift Zone and the Koaʻe fault system (Kīlauea volcano, Hawai ‘i) using photogrammetry and structural observations
Volcanic islands are often subject to flank instability, resulting from a combination of magmatic intrusions along rift zones and gravitational spreading causing extensional faulting at the surface. Here, we study the Koaʻe fault system (KFS), located south of the summit caldera of Kīlauea volcano in Hawaiʻi, one of the most active volcanoes on Earth, prone to active faulting, episodic...
Authors
Stefano Mannini, Joël Ruch, Richard W. Hazlett, Drew T. Downs, Carolyn Parcheta, Steven P. Lundblad, James Anderson, Ryan L. Perroy, Nicolas Oestreicher
Explosive trachyte eruptions from the Al Efairia volcanic center in northern Harrat Rahat, Kingdom of Saudi Arabia
Harrat Rahat is an alkali basalt, continental, intraplate volcanic field located within the central-western part of the Kingdom of Saudi Arabia. The northern quarter of Harrat Rahat contains evolved volcanic products that achieve trachyte compositions (>60 weight percent SiO2). Within the Al Efairia volcanic center, pyroclastic-flow and -surge deposits that reflect explosive trachyte...
Authors
Drew T. Downs, Mark E. Stelten, Hannah R. Dietterich, Duane E. Champion, Gail A. Mahood, Thomas W. Sisson, Andrew T. Calvert, Jamal Shawali
Paleomagnetism of the Harrat Rahat volcanic field, Kingdom of Saudi Arabia—Geologic unit correlations and geomagnetic cryptochron identifications
Paleomagnetic rock samples were collected from 173 drill sites in the Quaternary alkali basaltic volcanic field of northern Harrat Rahat, Kingdom of Saudi Arabia. Laboratory measurements on these samples established that lava flows and vent complexes—identified and mapped from field characteristics, rock types, and compositions as products of single or temporally close eruptions...
Authors
Duane E. Champion, Drew T. Downs, Mark E. Stelten, Joel E. Robinson, Thomas W. Sisson, Jamal Shawali, Khalid Hassan, Hani M. Zahran
The duration and characteristics of magmatic differentiation from basalt to trachyte within the Matan volcanic center, northern Harrat Rahat, Kingdom of Saudi Arabia
A fundamental goal of igneous petrology is to quantify the durations required to produce evolved magmas following influx of basalt into the crust. However, in many cases, complex field relations and (or) the presence of a long-lived magmatic system make it difficult to assess how basaltic inputs relate to more evolved magmas, therefore precluding calculation of meaningful timescales...
Authors
Mark E. Stelten, Drew T. Downs, Hannah R. Dietterich, Gail A. Mahood, Andrew T. Calvert, Thomas W. Sisson, Molly R. Witter, Hani M. Zahran, Jamal Shawali
Lava flow emplacement in Harrat Rahat with implications for eruptions in mafic volcanic fields
Mafic volcanic fields are widespread, but few have erupted in historical times, providing limited observations of the magnitudes, dynamics, and timescales of lava flow emplacement in these settings. The Harrat Rahat volcanic field in western Saudi Arabia offers a good opportunity to study eruptions in such a setting, with a historical eruption in 1256 C.E. (654 in the year of the Hijra)...
Authors
Hannah R. Dietterich, Drew T. Downs, Mark E. Stelten
Eruptive history of northern Harrat Rahat—Volume, timing, and composition of volcanism over the past 1.2 million years
Harrat Rahat, one of several large, basalt-dominated volcanic fields in the western part of the Kingdom of Saudi Arabia, is a prime example of continental, intraplate volcanism. Excellent exposure makes this an outstanding site to investigate changing volcanic flux and composition through time. We present 93 40Ar/39Ar ages and 6 36Cl surface-exposure ages for volcanic deposits throughout...
Authors
Mark E. Stelten, Drew T. Downs, Duane E. Champion, Hannah R. Dietterich, Andrew T. Calvert, Thomas W. Sisson, Gail A. Mahood, Hani M. Zahran
Non-USGS Publications**
Downs, D.T., Rowland, J.V., Wilson, C.J.N., Rosenberg, M.D., Leonard, G.S., and Calvert, A.T., 2014, Evolution of the intra-arc Taupo-Reporoa Basin within the Taupo Volcanic Zone of New Zealand: Geopshere, v. 10, p. 185-206, doi:10.1130/GES00965.1.
Downs, D.T., Wilson, C.J.N., Cole, J.W., Rowland, J.V., Calvert, A.T., Leonard, G.S., and Keall, J.M., 2014, Age and eruptive center of the Paeroa Subgroup ignimbrites (Whakamaru Group) within the Taupo Volcanic Zone of New Zealand: Geological Society of America Bulletin, v. 126, p. 1131-1144, doi:10.1130/B30891.1.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Sample details and near-real-time ED-XRF data collected during the 2020-2023 Halema‘uma‘u eruptions of Kīlauea volcano, Island of Hawaiʻi
A limited suite of samples for the 2020–2023 Kīlauea eruptions within Kaluapele (the summit caldera) were collected by the U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) field teams from within a publicly closed area of Hawai‘i Volcanoes National Park in cooperation with the National Park Service. This data release presents sample metadata, whole rock ED-XRF, whole rock WD...
Whole rock and micro-analytical geochemistry of minerals, melt inclusions, and matrix glasses from Kapoho Crater and Puʻulena Crater, Kīlauea Volcano, Hawaiʻi
Kilauea volcano (Hawaii, USA) is a shield volcano that exhibits both effusive and explosive eruptive activity. Although Kilauea has been predominantly built through effusive eruptions, explosive eruptions have occurred repeatedly at both Kilauea's summit and in the volcano's lower East Rift Zone (Moore, 1992; Swanson et al., 2014). This dataset presents geochemical analyses of samples...
Vesicularity, grain size, and grain shape of basaltic pyroclasts from Kīlauea and Mauna Loa volcanoes, Island of Hawaiʻi
This dataset includes sample information, vesicularity by pycnometer, grain size and shape data by CAMSIZER, and measurements of crushed and thin section mounted grains by microscope. All studied samples were from scoria and air-fall-tephra deposits (most formed in Hawaiian lava fountains) collected around the summits of Mauna Loa and Kīlauea volcanoes, Island of Hawaiʻi. These data were...
Major- and trace-element chemical analyses of whole-rock and glass from the Kamakaiʻa Hills of the Southwest Rift Zone of Kīlauea volcano, Hawaiʻi
This dataset includes wavelength dispersive X-ray fluorescence (WD-XRF) major-oxide and trace-element whole-rock analyses, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) trace-element whole-rock analyses, and glass analyses by electron microprobe of scoria and lava samples from the Kamakaiʻa Hills of the Southwest Rift Zone of Kīlauea volcano, Island of Hawaiʻi...
Colorimeter data for the summit water lake at Kīlauea Volcano, Island of Hawaiʻi, 2020
In 2018, a large effusive eruption on the lower flank of Kīlauea Volcano was associated with collapse and subsidence of the summit caldera floor (Neal and others, 2019). The bottom of Halemaʻumaʻu, a crater nested within the summit caldera, subsided by more than 500 m. In July 2019, water was observed ponding on the deepest part of the Halemaʻumaʻu crater floor and the water rose and...
Sample details and near-real-time ED-XRF, grain size, and grain shape data collected during the November – December 2022 eruption of Mauna Loa volcano, Island of Hawaiʻi
At 11:21 p.m. (Hawaii Standard Time [HST]) on November 27, 2022, Mauna Loa volcano on the Island of Hawaiʻi started erupting from fissures at its summit caldera, Mokuʻāweoweo. This was followed shortly afterwards by the opening of a segment of fissures in the direction of the Southwest Rift Zone. These were mostly within the structural boundary of the caldera, so their location is...
Electron microprobe data for plagioclase, olivine, pyroxene, and spinel in volcanic rocks from the Matan volcanic center located within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
Mineral compositions are reported for Quaternary volcanic rocks of the Matan volcanic center, northern Harrat Rahat, Saudi Arabia. Compositions were measured by wavelength-dispersive methods with the 5-spectrometer JEOL-8900 electron microprobe at the USGS facility in Menlo Park, California; background-corrected X-ray intensities were reduced to oxide weight concentrations with the JEOL...
Water-level data for the crater lake at the summit of Kilauea Volcano, Island of Hawai'i, 2019-2020
During 2018, Kilauea Volcano, on the Island of Hawaiii, had a large effusive eruption (~1 cubic kilometer of lava) on the lower East Rift Zone that caused widespread destruction (Neal and others, 2019; Dietterich and others, 2021). This lower flank eruption was accompanied by one of the largest collapses of the summit caldera in two hundred years, with portions of the caldera floor...
Database for the geologic map of the Paeroa Fault block and surrounding area, Taupo Volcanic Zone, New Zealand
The Taupo Volcanic Zone (TVZ), New Zealand, is the most productive area of explosive silicic volcanism in the world. Faulted early and middle Pleistocene volcanic products are generally concealed beneath voluminous, generally unfaulted, younger volcanic products. An exception is the southeast margin of the TVZ where the two parallel, northeast-trending Paeroa and Te Weta Fault blocks...
Database for the Geologic Map of the Northern Harrat Rahat Volcanic Field, Kingdom of Saudi Arabia
The Harrat Rahat volcanic field, located in the west-central part of the Kingdom of Saudi Arabia, is the largest of 15 harrats (Arabic for 'volcanic field') hosted within the Arabian plate. Harrat Rahat is 50 to 75 km wide (east-west) and 300 km long (north-south), covering an area of approximately 20,000 square kilometers and encompassing more than 900 observable vents. The overall map...
Geologic map of the northern Harrat Rahat volcanic field, Kingdom of Saudi Arabia
Harrat Rahat, in the west-central part of the Kingdom of Saudi Arabia, is the largest of 15 Cenozoic harrats (Arabic for “volcanic field”) distributed on the Arabian plate. It extends more than 300 km north-south and 50 to 75 km east-west, and it covers an area of approximately 20,000 km2, has a volume of approximately 2,000 km3, and encompasses more than 900 observable vents. Volcanism...
Drew Downs in Iceland
Drew Downs in Iceland with a glacier in hte background.
Drew Downs in Iceland with a glacier in hte background.
Filter Total Items: 26
Awakening of Maunaloa linked to melt shared from Kilauea’s mantle source
Maunaloa—the largest active volcano on Earth—erupted in 2022 after its longest known repose period (~38 years) and two decades of volcanic unrest. This eruptive hiatus at Maunaloa encompasses most of the ~35-year-long Puʻuʻōʻō eruption of neighboring Kīlauea, which ended in 2018 with a collapse of the summit caldera and an unusually voluminous (~1 km3) rift eruption. A long-term pattern...
Authors
Aaron J. Pietruszka, Daniel E. Heaton, Jared P. Marske, Marc D. Norman, Mahinaokalani G. Robbins, Reed B. Mershon, Kendra J. Lynn, Drew T. Downs, Arron R. Steiner, J. Michael Rhodes, Michael O. Garcia
Triggering the 2022 eruption of Mauna Loa
Distinguishing periods of intermittent unrest from the run-up to eruption is a major challenge at volcanoes around the globe. Comparing multidisciplinary monitoring data with mineral chemistry that records the physical and spatio-temporal evolution of magmas fundamentally advances our ability to forecast eruptions. The recent eruption of Mauna Loa, Earth’s largest active volcano...
Authors
Kendra J. Lynn, Drew T. Downs, Frank A. Trusdell, Penny E. Wieser, Berenise Rangel, Baylee Rose McDade, Alicia J. Hotovec-Ellis, Ninfa Lucia Bennington, Kyle R. Anderson, Dawn Catherine Sweeney Ruth, Charlotte DeVitre, Andria P. Ellis, Patricia A. Nadeau, Laura E. Clor, Peter J. Kelly, Peter Dotray, Jefferson Chang
Depths in a day - A new era of rapid-response Raman-based barometry using fluid inclusions
Rapid-response petrological monitoring is a major advance for volcano observatories, allowing them to build and validate models of plumbing systems that supply eruptions in near-real-time. The depth of magma storage has recently been identified as high-priority information for volcanic observatories, yet this information is not currently obtainable via petrological monitoring methods on...
Authors
Charlotte DeVitre, Penny E. Wieser, Alexander T. Bearden, Araela Richie, Berenise Rangel, Matthew Gleeson, John Grimsich, Kendra J. Lynn, Drew T. Downs, Natalia I. Deligne, Katherine M. Mulliken
Volcanoes of American Samoa
Upu Amata (Introduction)O le Atu-Samoa o le tasi lenei o faʻasologa motu mauga mu i le Vasa Pasefika i Saute. O motu e pito i sasaʻe o nei faʻasologa mauga mu o le Atu-Samoa, o motu ia o Amerika Samoa. E tofu lava mauga mu taʻitasi o Amerika Samoa ma ona talaaga aemaise tulaga e tutupu e ono pa ai i le lumanai. O loʻo galulue faʻatasi le Ofisa o le U.S. Geological Survey (USGS) ma le...
Authors
Natalia I. Deligne, Drew T. Downs, Elinor Lutu-McMoore, Steven Sobieszczyk, Wendy K. Stovall
The influence of vesicularity on grain morphology in basaltic pyroclasts from Mauna Loa and Kīlauea volcanoes
Vesicularity of individual pyroclasts from airfall tephra deposits is an important parameter that is commonly measured at basaltic volcanoes. Conventional methods used to determine pyroclast vesicularity on a large number of clasts has the potential to be time consuming, particularly when rapid analysis is required. Here we propose dynamic image analysis on two-dimensional (2D)...
Authors
Kira van Helden, Johanne Schmith, Drew T. Downs
Origins and nature of large explosive eruptions in the lower East Rift Zone of Kīlauea volcano, Hawaii: Insights from ash characterization and geochemistry
Several powerful explosive eruptions have taken place in the populated lower East Rift Zone of Kīlauea within the past ∼750 years. These have created distinctive landforms, including a tephra rim enclosing Puʻulena Crater immediately south of the Puna Geothermal Venture power station, a tuff cone at Kapoho Crater near the eastern cape of the Island of Hawaiʻi, and a set of littoral cones...
Authors
Richard W. Hazlett, Johanne Schmith, Allan Lerner, Drew T. Downs, Erin P. Fitch, Carolyn E. Parcheta, Cheryl A. Gansecki, Sarah Spaulding
Tracking magma pathways and surface faulting in the Southwest Rift Zone and the Koaʻe fault system (Kīlauea volcano, Hawai ‘i) using photogrammetry and structural observations
Volcanic islands are often subject to flank instability, resulting from a combination of magmatic intrusions along rift zones and gravitational spreading causing extensional faulting at the surface. Here, we study the Koaʻe fault system (KFS), located south of the summit caldera of Kīlauea volcano in Hawaiʻi, one of the most active volcanoes on Earth, prone to active faulting, episodic...
Authors
Stefano Mannini, Joël Ruch, Richard W. Hazlett, Drew T. Downs, Carolyn Parcheta, Steven P. Lundblad, James Anderson, Ryan L. Perroy, Nicolas Oestreicher
Explosive trachyte eruptions from the Al Efairia volcanic center in northern Harrat Rahat, Kingdom of Saudi Arabia
Harrat Rahat is an alkali basalt, continental, intraplate volcanic field located within the central-western part of the Kingdom of Saudi Arabia. The northern quarter of Harrat Rahat contains evolved volcanic products that achieve trachyte compositions (>60 weight percent SiO2). Within the Al Efairia volcanic center, pyroclastic-flow and -surge deposits that reflect explosive trachyte...
Authors
Drew T. Downs, Mark E. Stelten, Hannah R. Dietterich, Duane E. Champion, Gail A. Mahood, Thomas W. Sisson, Andrew T. Calvert, Jamal Shawali
Paleomagnetism of the Harrat Rahat volcanic field, Kingdom of Saudi Arabia—Geologic unit correlations and geomagnetic cryptochron identifications
Paleomagnetic rock samples were collected from 173 drill sites in the Quaternary alkali basaltic volcanic field of northern Harrat Rahat, Kingdom of Saudi Arabia. Laboratory measurements on these samples established that lava flows and vent complexes—identified and mapped from field characteristics, rock types, and compositions as products of single or temporally close eruptions...
Authors
Duane E. Champion, Drew T. Downs, Mark E. Stelten, Joel E. Robinson, Thomas W. Sisson, Jamal Shawali, Khalid Hassan, Hani M. Zahran
The duration and characteristics of magmatic differentiation from basalt to trachyte within the Matan volcanic center, northern Harrat Rahat, Kingdom of Saudi Arabia
A fundamental goal of igneous petrology is to quantify the durations required to produce evolved magmas following influx of basalt into the crust. However, in many cases, complex field relations and (or) the presence of a long-lived magmatic system make it difficult to assess how basaltic inputs relate to more evolved magmas, therefore precluding calculation of meaningful timescales...
Authors
Mark E. Stelten, Drew T. Downs, Hannah R. Dietterich, Gail A. Mahood, Andrew T. Calvert, Thomas W. Sisson, Molly R. Witter, Hani M. Zahran, Jamal Shawali
Lava flow emplacement in Harrat Rahat with implications for eruptions in mafic volcanic fields
Mafic volcanic fields are widespread, but few have erupted in historical times, providing limited observations of the magnitudes, dynamics, and timescales of lava flow emplacement in these settings. The Harrat Rahat volcanic field in western Saudi Arabia offers a good opportunity to study eruptions in such a setting, with a historical eruption in 1256 C.E. (654 in the year of the Hijra)...
Authors
Hannah R. Dietterich, Drew T. Downs, Mark E. Stelten
Eruptive history of northern Harrat Rahat—Volume, timing, and composition of volcanism over the past 1.2 million years
Harrat Rahat, one of several large, basalt-dominated volcanic fields in the western part of the Kingdom of Saudi Arabia, is a prime example of continental, intraplate volcanism. Excellent exposure makes this an outstanding site to investigate changing volcanic flux and composition through time. We present 93 40Ar/39Ar ages and 6 36Cl surface-exposure ages for volcanic deposits throughout...
Authors
Mark E. Stelten, Drew T. Downs, Duane E. Champion, Hannah R. Dietterich, Andrew T. Calvert, Thomas W. Sisson, Gail A. Mahood, Hani M. Zahran
Non-USGS Publications**
Downs, D.T., Rowland, J.V., Wilson, C.J.N., Rosenberg, M.D., Leonard, G.S., and Calvert, A.T., 2014, Evolution of the intra-arc Taupo-Reporoa Basin within the Taupo Volcanic Zone of New Zealand: Geopshere, v. 10, p. 185-206, doi:10.1130/GES00965.1.
Downs, D.T., Wilson, C.J.N., Cole, J.W., Rowland, J.V., Calvert, A.T., Leonard, G.S., and Keall, J.M., 2014, Age and eruptive center of the Paeroa Subgroup ignimbrites (Whakamaru Group) within the Taupo Volcanic Zone of New Zealand: Geological Society of America Bulletin, v. 126, p. 1131-1144, doi:10.1130/B30891.1.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.