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
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 enlarged in
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 denoted as ‘Sout
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 subsiding more
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 expose Quater
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 area and i
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 commenced
A multidisciplinary investigation into the eruptive style, processes, and duration of a Cascades back-arc tholeiitic basalt: A case study of the Brushy Butte flow field, northern California, United States
The Cascades back-arc in northern California is dominated by monogenetic tholeiitic basalts that erupted throughout the Pleistocene. Elucidating their eruptive history and processes is important for understanding potential future eruptions here. We focus on the well-exposed monogenetic volcano that emplaced the Brushy Butte flow field, which constructed a ∼150 m tall edifice, has flow lobes up to
Authors
Drew T. Downs, Duane E. Champion, Michael A. Clynne, L. J. Patrick Muffler
Simultaneous Middle Pleistocene eruption of three widespread tholeiitic basalts in northern California (USA): Insights into crustal magma transport in an actively extending back arc
Mapping and chronology are central to understanding spatiotemporal volcanic trends in diverse tectonic settings. The Cascades back arc in northern California (USA) hosts abundant lava flows and normal faults, but tholeiitic basalts older than 200 ka are difficult to discriminate by classic mapping methods. Paleomagnetism and chemistry offer independent means of correlating basalts, including the T
Authors
Drew T. Downs, Duane E. Champion, L. J. Patrick Muffler, Robert L. Christiansen, Michael A. Clynne, Andrew T. Calvert
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 expose Quater
Authors
Drew T. Downs, Graham S. Leonard, Colin J. N. Wilson, Julie V Rowland
Eruption age and duration of the ~9 km3 Burney Mountain dacite dome complex, northern California
At ~9 km3, the six dacite domes of Burney Mountain (db1–db6) constitute the most voluminous Quaternary dome complex in the Cascades volcanic arc. Whole-rock geochemistry, electron microprobe, and petrographic data indicate that the domes are magmatically related, which, when integrated with geomorphology and stratigraphy, indicate early (db1, db2, db3) and late (db4, db5, db6) erupted groups. We
Authors
Drew T. Downs, Michael A. Clynne, Duane E. Champion, L. J. Patrick Muffler
Reconstructing lava flow emplacement histories with rheological and morphological analyses: the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
Mafic volcanic fields are widespread, but few have erupted in historic times, providing limited observations of the magnitudes, dynamics, and timescales of lava flow emplacement in these settings. To expand our knowledge of effusive mafic eruptions, we must evaluate solidified flows to discern syn-eruptive conditions. The Harrat Rahat volcanic field in western Saudi Arabia offers a good opportunit
Authors
Hannah R. Dietterich, Drew T. Downs, Mark E. Stelten, Hani Zahran
Timescales of magmatic differentiation from alkali basalt to trachyte within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
A fundamental goal of igneous petrology is to quantify the duration of time 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. Here, w
Authors
Mark E. Stelten, Drew T. Downs, Hannah R. Dietterich, Gail A. Mahood, Andrew T. Calvert, Thomas W. Sisson, Hani Zahran, Jamal Shawali
Volcanic history of the northernmost part of the Harrat Rahat volcanic field, Saudi Arabia
We present a detailed geologic investigation of Pleistocene to Holocene mafic volcanism within the northernmost part of the Harrat Rahat volcanic field, proximal to the city of Al-Madinah, Saudi Arabia. Our study area covers ∼570 km2, and encompasses lava flows, scoria cones, and shield volcanoes of 32 mapped eruptive units consisting of continental, intraplate alkalic and tholeiitic basalts, hawa
Authors
Drew T. Downs, Mark E. Stelten, Duane E. Champion, Hannah R. Dietterich, Zohair Nawab, Hani Zahran, Khalid Hassan, Jamal Shawali
Age of the youngest volcanism at Eagle Lake, northeastern California—40Ar/39Ar and paleomagnetic results
The age of the youngest volcanism at Eagle Lake, California, was investigated using stratigraphic, paleomagnetic, and 40Ar/39Ar techniques. The three youngest volcanic lava flows at Eagle Lake yielded ages of 130.0±5.1, 127.5±3.2 and 123.6±18.7 ka, and are statistically indistinguishable. Paleomagnetic results demonstrate that two of the lava flows are very closely spaced in time, whereas the thir
Authors
Michael A. Clynne, Andrew T. Calvert, Duane E. Champion, L. J. P. Muffler, Michael G. Sawlan, Drew T. Downs
Mihi Breccia: A stack of lacustrine sediments and subaqueous pyroclastic flows within the Taupo Volcanic Zone, New Zealand
The Taupo Volcanic Zone (TVZ), New Zealand, encompasses a wide variety of arc-related strata, although most of its small-volume (non-caldera-forming) eruptions are poorly-exposed and extensively hydrothermally altered. The Mihi Breccia is a stratigraphic sequence consisting of interbedded rhyolitic pyroclastic flows and lacustrine sediments with eruption ages of 281 ± 18 to at least 239 ± 6 ka (un
Authors
Drew T. Downs
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
- Data
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 enlarged inSample 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 denoted as ‘SoutWater-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 subsiding moreDatabase 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 expose QuaterDatabase 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 area and i - Maps
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 commenced - Multimedia
- Publications
A multidisciplinary investigation into the eruptive style, processes, and duration of a Cascades back-arc tholeiitic basalt: A case study of the Brushy Butte flow field, northern California, United States
The Cascades back-arc in northern California is dominated by monogenetic tholeiitic basalts that erupted throughout the Pleistocene. Elucidating their eruptive history and processes is important for understanding potential future eruptions here. We focus on the well-exposed monogenetic volcano that emplaced the Brushy Butte flow field, which constructed a ∼150 m tall edifice, has flow lobes up toAuthorsDrew T. Downs, Duane E. Champion, Michael A. Clynne, L. J. Patrick MufflerSimultaneous Middle Pleistocene eruption of three widespread tholeiitic basalts in northern California (USA): Insights into crustal magma transport in an actively extending back arc
Mapping and chronology are central to understanding spatiotemporal volcanic trends in diverse tectonic settings. The Cascades back arc in northern California (USA) hosts abundant lava flows and normal faults, but tholeiitic basalts older than 200 ka are difficult to discriminate by classic mapping methods. Paleomagnetism and chemistry offer independent means of correlating basalts, including the TAuthorsDrew T. Downs, Duane E. Champion, L. J. Patrick Muffler, Robert L. Christiansen, Michael A. Clynne, Andrew T. CalvertGeologic 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 expose QuaterAuthorsDrew T. Downs, Graham S. Leonard, Colin J. N. Wilson, Julie V RowlandEruption age and duration of the ~9 km3 Burney Mountain dacite dome complex, northern California
At ~9 km3, the six dacite domes of Burney Mountain (db1–db6) constitute the most voluminous Quaternary dome complex in the Cascades volcanic arc. Whole-rock geochemistry, electron microprobe, and petrographic data indicate that the domes are magmatically related, which, when integrated with geomorphology and stratigraphy, indicate early (db1, db2, db3) and late (db4, db5, db6) erupted groups. WeAuthorsDrew T. Downs, Michael A. Clynne, Duane E. Champion, L. J. Patrick MufflerReconstructing lava flow emplacement histories with rheological and morphological analyses: the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
Mafic volcanic fields are widespread, but few have erupted in historic times, providing limited observations of the magnitudes, dynamics, and timescales of lava flow emplacement in these settings. To expand our knowledge of effusive mafic eruptions, we must evaluate solidified flows to discern syn-eruptive conditions. The Harrat Rahat volcanic field in western Saudi Arabia offers a good opportunitAuthorsHannah R. Dietterich, Drew T. Downs, Mark E. Stelten, Hani ZahranTimescales of magmatic differentiation from alkali basalt to trachyte within the Harrat Rahat volcanic field, Kingdom of Saudi Arabia
A fundamental goal of igneous petrology is to quantify the duration of time 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. Here, wAuthorsMark E. Stelten, Drew T. Downs, Hannah R. Dietterich, Gail A. Mahood, Andrew T. Calvert, Thomas W. Sisson, Hani Zahran, Jamal ShawaliVolcanic history of the northernmost part of the Harrat Rahat volcanic field, Saudi Arabia
We present a detailed geologic investigation of Pleistocene to Holocene mafic volcanism within the northernmost part of the Harrat Rahat volcanic field, proximal to the city of Al-Madinah, Saudi Arabia. Our study area covers ∼570 km2, and encompasses lava flows, scoria cones, and shield volcanoes of 32 mapped eruptive units consisting of continental, intraplate alkalic and tholeiitic basalts, hawaAuthorsDrew T. Downs, Mark E. Stelten, Duane E. Champion, Hannah R. Dietterich, Zohair Nawab, Hani Zahran, Khalid Hassan, Jamal ShawaliAge of the youngest volcanism at Eagle Lake, northeastern California—40Ar/39Ar and paleomagnetic results
The age of the youngest volcanism at Eagle Lake, California, was investigated using stratigraphic, paleomagnetic, and 40Ar/39Ar techniques. The three youngest volcanic lava flows at Eagle Lake yielded ages of 130.0±5.1, 127.5±3.2 and 123.6±18.7 ka, and are statistically indistinguishable. Paleomagnetic results demonstrate that two of the lava flows are very closely spaced in time, whereas the thirAuthorsMichael A. Clynne, Andrew T. Calvert, Duane E. Champion, L. J. P. Muffler, Michael G. Sawlan, Drew T. DownsMihi Breccia: A stack of lacustrine sediments and subaqueous pyroclastic flows within the Taupo Volcanic Zone, New Zealand
The Taupo Volcanic Zone (TVZ), New Zealand, encompasses a wide variety of arc-related strata, although most of its small-volume (non-caldera-forming) eruptions are poorly-exposed and extensively hydrothermally altered. The Mihi Breccia is a stratigraphic sequence consisting of interbedded rhyolitic pyroclastic flows and lacustrine sediments with eruption ages of 281 ± 18 to at least 239 ± 6 ka (unAuthorsDrew T. DownsNon-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.