Gregory R. Brooks

Gregory R. Brooks
Natural Resources Canada | NRCan · Geological Survey of Canada

Doctor of Philosophy

About

97
Publications
41,989
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
964
Citations
Citations since 2017
34 Research Items
437 Citations
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
Introduction
I am geomorphologist with the Geological Survey of Canada. My research is in the field of natural hazards. Currently, my research is investigating evidence of paleoseismicity on the Canadian Shield in eastern Canada, using the chronology of sensitive clay landslides or mapping synchronously-triggered subaqueous landslides preserved in lake basins.

Publications

Publications (97)
Article
Full-text available
A landslide debris field covering ~ 31 km2, the presence of large sediment blocks up to hundreds of meters long, and the exposure of deposits of a single landslide along the incised course of the Quyon River are evidence of a massive failure of sensitive Champlain Sea glaciomarine sediments along the lower Quyon Valley, southwestern Quebec, Canada....
Article
As part of an investigation of deglacial palaeoseismology within an intracratonic region of north‐eastern North America, the compilation of sub‐bottom acoustic profile surveys from study areas at Duparquet and Dufresnoy lakes, north‐western Quebec, Canada, produced thirteen and eight event horizon maps, respectively, depicting subaqueous mass trans...
Article
To test an inference that the New Liskeard–Thornloe scarp (NLTS), Timiskaming graben, Ontario, is a deglacial–postglacial seismo-neotectonic fault, we collected shallow geophysical data along lines 7.2, 0.28, and 0.52 km long, located on three roads crossing the middle portion of the scarp. Data revealed a valley subsurface composed of bedrock (sei...
Article
Evidence of early postglacial, glacially-induced seismic activity should be abundant in eastern Canada, which was formerly covered by the Laurentide Ice Sheet during the late Wisconsinan Glaciation. This review identified only two 'probable' and at most nine 'possible' examples of glacially-induced faulting over an area of ~4 million km 2 , a far l...
Article
This paper reviews and expands upon stratigraphic and chronologic evidence supporting the interpretation of a strong, early postglacial paleoearthquake in western Quebec-northeastern Ontario, Canada. Event horizon mapping at Dasserat, Dufresnoy and Duparquet lakes, Quebec, coring at Chassignolle and Malartic lakes, Quebec, analysis of varve exposur...
Technical Report
Full-text available
The thicknesses of 384 rhythmic couplets were measured along a composite sequence of glacial Lake Ojibway glaciolacustrine deposits recovered in two sediment cores from Frederick House Lake, Ontario. The visual comparison of distinctive couplets in the CT-scan radiographs of the Frederick House core samples to photographs of core samples from Reid...
Chapter
Glacially triggered faulting describes movement of pre-existing faults caused by a combination of tectonic and glacially induced isostatic stresses. The most impressive fault-scarps are found in northern Europe, assumed to be reactivated at the end of the deglaciation. This view has been challenged as new faults have been discovered globally with a...
Article
A sub-bottom acoustic profile survey encountered a mass transport deposit (MTD) bed, 5-7 m thick, interbedded within glaciolacustrine deposits of glacial Lake Ojibway at Frederick House Lake, Ontario. Analysis of the thickness patterns of rhythmic couplets in recovered core samples revealed that the Connaught sequence, the youngest of the Timiskami...
Technical Report
Full-text available
This Open File is an updated compilation of 167 published and unpublished radiocarbon dates relating directly or indirectly to the ages of 45 landslides or landslide complexes in sensitive clay, and three “disturbed terrain” features in the Ottawa Valley, southeastern Ontario/southwestern Quebec. Twenty-three tables contain dates for individual lan...
Article
We provide a GIS data inventory of confirmed and proposed glacially-induced faults. Stresses, perturbated as a response to the advance and retreat of continental ice sheets and glaciers, can reactivate pre-existing faults. Previously referred to as "PostGlacial Faults" (PGFs), these faults are now called "Glacially-Induced Faults" (GIFs). More than...
Technical Report
Full-text available
This report presents a retrogressive, sensitive clay landslide inventory map and database compiled for the area bound approximately by the City of Ottawa, derived from a high-resolution, bare earth DEM derived from a LiDAR survey. The main map is supplemented by 20 inset maps that are enlargements of the isolated or groups of landslides. The invent...
Preprint
Full-text available
The thicknesses of 537 and 387 rhythmic couplets were measured along composite sequences of glacial Lake Ojibway glaciolacustrine deposits recovered in cores from Duparquet and Dufresnoy lakes, Quebec, respectively. The couplets span varve numbers 1137 to 1742 (Lac Duparquet) and 1189 to 1625 (Lac Dufresnoy) with respect to the Timiskaming varve se...
Chapter
Full-text available
Located between the Manitoba Escarpment (known as the Pembina Escarpment in North Dakota) and a gentle topographic rise to late Quaternary glacial deposits, the Red River valley forms the southern extension of the Manitoba Lowlands. The dominant landform of the central valley is a low-relief clay plain composed of glacilacustrine deposits that accu...
Data
Full-text available
Data
Full-text available
Data
Full-text available
Data
Full-text available
Data
Full-text available
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 25 profiles were collected at Swan Lake, Ontario, on August 17, 2015. The quality of the returns ranges from good to no penetration, probably reflecting variations in the present of methane gas in the sediments. Three facies are present within the SAP returns that represent lac...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 22 profiles were collected at Lac Taschereau, Quebec, on August 21, 2015. There generally is good penetration into the sub-bottom along most profiles, except in the central and northern portions of the basin where there was no penetration. Three depositional facies are present...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 23 SAP were collected from Lac Joannès, Quebec, on August 22, 2015. Good penetration of the sub-bottom was obtained within the profiled areas. Three depositional facies are present within the SAP returns that represent lacustrine, glaciolacustrine and mass transport deposits. T...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 34 profiles were collected at Sesekinika Lake, Ontario, on August 23, 2015. The quality of the returns ranges from good to there being no penetration locally. Three depositional facies are present within the SAP returns that represent lacustrine, glaciolacustrine and subaqueous...
Data
Full-text available
Technical Report
Full-text available
Cores recovered from six sites within a study area, ~3 km2, at Lac Dasserat, northwestern Quebec, contained varved Lake Ojibway glaciolacustrine deposits. Measurements of the thicknesses of 546 couplets follow a composite sequence of varves through the recovered deposits. The couplets are interpreted to span varve numbers 1039 to 1637 with respect...
Article
An integrated seismo- and chronostratigraphic investigation at Lac Dasserat, northwestern Quebec, identified 74 separate failures within eight event horizons. Horizons E and B, and H and G have strong or moderately-strong multi-landslide signatures, respectively, composed of 11–23 failures, while horizons F, D, C, and A have minor landslide signatu...
Technical Report
Full-text available
As a part of reconnaissance sub-bottom acoustic profiling (SAP) survey on Lac Opasatica, Quebec, 19 SAP were collected from the northern bay area and 27 SAP were collected within Baie Lamy on July 15 and 18, 2014, respectively. Good penetration of the sub-bottom was obtained in most of the two profiled areas. Three facies can be identified within t...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 22 SAP were collected from Lac Kinojévis, Quebec, on July 11, 2014. The eight profiles with the best penetration were located in the southeastern, narrower area of the lake. Two depositional facies can be identified within the SAP returns that represent lacustrine-fluvial and g...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 36 SAP were collected along the northern area of Lac Duparquet, Quebec, on July 17, 2014. There is good penetration into the sub-bottom along most of the profiles. Three depositional facies are present within the SAP returns that represent lacustrine, glaciolacustrine and mass...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, twenty-two and one SAP were collected from lakes Dufresnoy and Lac Petit Dufresnoy, Quebec, respectively, on July 19, 2014. There is good penetration of the sub-bottom along many of the profiles. Three depositional facies can be identified within the SAP returns that represent...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, eleven SAP were collected from Lac Macamic, Quebec, on July 21, 2014. Good penetration of the sub-bottom was obtained in both of the profiled bays. Three facies can be identified within the SAP returns that represent lacustrine, glaciolacustrine and mass movement deposits. The...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 29 SAP were collected from the southern area of the east basin of Larder Lake, Ontario, on July 20, 2014. An additional 25 SAP were collected from Leroy, Northwest and Fitzpatrick bays of the west basin on July 23, 2014. Good penetration of the sub-bottom was obtained within th...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, 32 SAP were collected from Lac Flavrian, Quebec, on July 14, 2014. The quality of the returns from Lac Flavrian are generally poor with there being little to no penetration of the sub-bottom along most of the profiles. Despite this, three depositional facies can be identified w...
Technical Report
Full-text available
As part of a reconnaissance sub-bottom acoustic profiling (SAP) survey, eleven SAP were collected from Lac Caste, Quebec, on July 10, 2014. The returns with the best penetration of the sub-bottom were collected in the small bay in the southern area of the lake and along the immediate south and west sides of the main basin. There was no penetration...
Chapter
Full-text available
The Red River, Manitoba, Canada, is a low-gradient, meandering river that traverses the broad, flat Red River Valley on the northeastern portion of the Great Plains of North America. The shallow stream-cut valley occupied by the river has insufficient capacity to contain large discharges, which allows higher magnitude flows to overtop the valley si...
Article
Full-text available
Seismic shaking can generate mass movements, turbidites, and soft-sediment deformation within lake basins. These ‘disturbed’ deposits may be preserved, and provide a stratigraphic record of paleoearthquakes. A three-dimensional seismostratigraphy of the lake deposits can be constructed from a high-density, sub-bottom acoustic profile (SAP) survey,...
Article
Full-text available
Although moderate in size (M-N 5.2, M 4.6), the earthquake that occurred near Ladysmith, Quebec, on 17 May 2013 was one of the best-recorded earthquakes to have occurred in eastern Canada in recent years due to the fortuitous deployment of US. Transportable Array stations in a region that was already well covered by the Canadian National Seismograp...
Chapter
Full-text available
The ages of 39 large retrogressive landslides and three areas of disturbed terrain in the Ottawa Valley were compiled using 122 published and unpublished radiocarbon ages. The chronological dataset includes 15 confined-valley landslides, 23 scarp-side landslides, and four special case features (one massive landslide, three disturbed terrain areas)....
Technical Report
Full-text available
This Open File contains a compilation of 122 published and unpublished radiocarbon dates relating to the age of 39 sensitive clay landslides and three “disturbed terrain” features in the Ottawa Valley, southeastern Ontario/southwestern Québec. Sixteen tables contain either the date(s) for individual landslides (or disturbed terrain) or the date(s)...
Article
The surficial geology of the city of Ottawa primarily consists of soft soil sediments with low shear-wave velocities (similar to 150 m/s) underlain by hard bedrock with very large shear-wave velocities (similar to 2700 m/s). Earthquake recordings show unusually large seismic amplification values for weak motion. These unusually large seismic amplif...
Article
Full-text available
Sub-bottom profiling was conducted at eight sub-basins within the lower French River area, Ontario, to investigate deposits preserved within the ancient North Bay outlet. Ten cores were collected that targeted the four depositional acoustic facies identified in the sub-bottom profiling records. The rhythmically laminated/bedded glaciolacustrine dep...
Article
Full-text available
Sub-bottom profiling and coring were undertaken at eight sub-basins along the lower French River and at five small lakes near North Bay, Ontario, to collect stratigraphical and chronological evidence to investigate whether lakes occupying the Huron–Georgian basins during the early- to mid-Holocene became hydrologically closed. All of the coring sit...
Article
Full-text available
As a part of our microzonation research activities for the city of Ottawa, the fundamental site period, T(0), was investigated based on different methods, including (1) the horizontal-to-vertical spectral ratio (HVSR) using microtremor ambient-noise measurements; (2) equivalent single-layer (ESL) modeling, as noted in the current National Building...
Article
A distinct white bed 1–2 cm thick is present within backwater deposits at the upstream end of the Turbid Creek debris fan, southwestern British Columbia, Canada. This white bed and the enclosing backwater deposits accumulated within an impoundment of Squamish River caused by a large ca. 4800 BP debris avalanche originating from Mount Cayley, a Plio...
Article
An investigation of diamicton units exposed in an extensive accumulation of volcanic debris in the Squamish valley, west of Mount Cayley volcano, has yielded evidence for at least three major debris avalanches, initiated by the collapse of the western flank of Mount Cayley in the mid-Holocene. Radiocarbon ages obtained from tree fragments contained...
Article
Squamish River has been impounded temporarily by debris avalanches from Mount Cayley on numerous occasions. Evidence of these impoundments comes from backwater deposits and also from a cluster of in situ stumps protruding from a bar along Squamish River. Backwater deposits consist of both lacustrine and fluvial deposits that have formed within the...
Article
An investigation of diamicton units exposed in an extensive accumulation of volcanic debris in the Squamish valley, west of Mount Cayley volcano, has yielded evidence for at least three major debris avalanches, initiated by the collapse of the western flank of Mount Cayley in the mid-Holocene. Radiocarbon ages obtained from tree fragments contained...
Article
The Ring Creek lava flow, extending from Opal Cone, generally is considered to be the youngest volcanic feature in the southern section of the Mount Garibaldi volcanic field, southwestern British Columbia. An in situ stump dated 10 650 ± 70 BP (Beta 43865) obtained from a raised delta partially overridden by the lava flow indicates that the lava wa...
Article
At some sites near Ottawa, Ontario, thick glaciomarine sediments deposited in the Champlain Sea after the final retreat of the Winsconsinan icesheet ∼11,000 years ago show evidence of severe "disturbance" by ground motions during a prehistoric earthquake(s). The Geological Survey of Canada has been investigating these areas to better understand sei...
Article
This paper describes a set of field data suitable for the testing and comparative assessment of geomorphic flood routing methods. The data pertain to a particularly severe and unusually well–documented flood event: the Lake Ha! Ha! breakout flood of July 1996 in the Saguenay Region of Québec. In this event, heavy rains combined with the incision of...
Technical Report
Full-text available
Technical Report on seismic site classification for the City of Ottawa, Ontario, Canada. Report uses Vs30 site classification in order to identify earthquake hazards.
Article
The city of Ottawa, Ontario, Canada, is in an area of elevated earthquake shaking hazard and is considered to be the Canadian city third-most at risk to damage (after Vancouver and Montreal). Maps showing regional variation of Vs30, fundamental site period, and an example map of the spectral accelerations at Sa=0.2s have been completed for the city...
Article
Earthquake Microzonation maps of the Ottawa area have been developed by a combined team of researchers from the Geological Survey of Canada (GSC) and Carleton University. The city of Ottawa has an areal extent of 2796 square kilometers, consisting of three basic geological/geotechnical units: bedrock outcrop (15%), a thin veneer of glacial deposits...
Conference Paper
Full-text available
Evidence of water levels below the present surfaces of the Laurentian Great Lakes was explained historically by overflow through northern outlets which were still differentially depressed by the retreating Laurentide Ice Sheet. This interpretation was challenged following a review of radiocarbon-dated, upwarped Late Wisconsinan and Holocene shoreli...
Article
Full-text available
Recent studies have produced a new understanding of the hydrological history of North America's Great Lakes, showing that water levels fell several meters below lake basin outlets during an early postglacial dry climate in the Holocene (younger than 10,000 radiocarbon years, or about 11,500 calibrated or calendar years before present (B.P.)). Water...
Article
Full-text available
Seismic techniques have been used to supplement geological and geophysical borehole data for assessing earthquake hazard in the Ottawa Valley near Ottawa, Ontario, Canada. The methodology Used to obtain critical parameters for site effect studies (depths of major contacts, shear-wave velocity-depth function) is presented ill this paper. Bedrock dep...
Article
Shear wave seismic test locations and boreholes have outlined a buried bedrock valley in the Ottawa, Ontario, suburb of Orleans. This region is in a significant high seismic hazard zone, and the surficial materials are primarily high water-content, poorly compacted Holocene-age Champlain Sea sediments. Since the in-filled sediments exhibit an extre...
Article
Full-text available
Slow earth sliding is pervasive along the concave side of Red River meanders that impinge on Lake Agassiz glaciolacustrine deposits. These failures form elongated, low-angled (c. 6 to 10°) landslide zones along the valleysides. Silty overbank deposits that accumulated during the 1999 spring freshet extend continuously along the landslide zones over...
Article
The north-flowing, low-gradient section of the Red River in Manitoba has lost-60%/o of its valley gradient since 8 ka cal. BP. An existing hydraulic model of the modem Red River flood zone was used to examine the change in flood extent and depth of a discharge equivalent to the 1997 Red River flood (3970 m3/s) for scenarios of gradients at 8, 6, 4...
Article
Full-text available
Optical dating studies of samples of late-Holocene mud-dominated alluvium, and heated alluvium in features interpreted to be hearths, collected from the banks of the Red River, southern Manitoba, Canada, were undertaken to assess the viability of these deposits as chronometers for floodplain evolution. Optical dating was done by utilizing the viole...
Article
Full-text available
The Holocene evolution of the shallow alluvial valley occupied by the Red River was investigated at two successive river meanders near St. Jean Baptiste, Manitoba. A transect of five boreholes was sited across the flood plain at each meander to follow the path of lateral channel migration. From the cores, 24 wood and charcoal samples were AMS radio...
Article
Full-text available
Abstract The Red River, Manitoba, is a mud-dominated, meandering stream that occupies a shallow valley eroded into a clay plain. The valley-bottom alluvium is the product of incision and lateral migration of river meanders. As revealed by a transect of five boreholes located across the floodplain at each of two successive river meanders, the alluvi...
Article
Overbank deposits that aggraded during the severe and moderate Red River, Manitoba and North Dakota floods of 1997 and 1999 were examined to characterize the typical diatom and thecamoebian flood assemblages. The deposits contain diatom assemblages dominated by Nitzschia spp., Stephanodiscus spp. and Navicula spp. as well as large quantities of Han...
Article
Full-text available
2-3, p. 151-158, 5 fig., 1 tabl. ABSTRACT Horseshoe Lake and the Marion Lake scar, along the Red River, southern Manitoba, were cored to investigate the tim- ing of the meander cutoffs and the sedimen- tology of the channel in-fill deposits. The Horseshoe Lake core, 10.75 m long, consists of 9.73 m of silt-rich deposits inferred to be lacustrine fr...
Article
Full-text available
This paper reports the accelerator mass spectrometry radiocarbon ages and geomorphic context of one bone and 38 charcoal samples collected from 12 floodplain exposures along the Red River, southern Manitoba. The stratigraphically oldest dates range from 3760 to 6710 cal BP and indicate that floodplain deposits of at least mid-Holocene age are prese...
Article
Full-text available
In Canada, flooding is caused by hydrometeorological mechanisms individually or in combination, and, less commonly, by the formation and failure of natural dams. Between 1900 and June 1997, there have been 168 known Canadian flood 'disasters'. These events are clustered in the south in Eastern Canada, whereas they generally are spread throughout We...
Article
Full-text available
The flat topography of the Red River Valley reflects the morphology of underlying bedrock covered with late Quaternary glacial and glaciolacustrine sediments. The meandering Red River occupies a shallow stream-cut valley that became incised into the Red River Valley plain following the final recession of glacial Lake Agassiz. Extreme flows carried...