#800-1045 howe street - · pdf file#800-1045 howe street vancouver, b.c. canada v6z 2a9 ......

Kinder Morgan Canada March 7, 2013

Faults in the Lower Mainland and Burnaby Mountain Project No.: 0095-150-03

20130307 Faults in the Lower Mainland and Burnaby Mountain.docx

BGC ENGINEERING INC.

#800-1045 Howe Street Vancouver, B.C. Canada V6Z 2A9 Tel: 604.684.5900 Fax: 604.684.5909

March 7, 2013 Project No.: 0095-150-03

Mr. Greg Toth, P.Eng. TMEP Project Director Kinder Morgan Canada Suite 2700, 300-5th Avenue SW Calgary, Alberta T2P 5J2

Dear Mr. Toth,

Re: Faults in the Lower Mainland and Burnaby Mountain

1.0 INTRODUCTION

This letter summarizes the tectonic setting of southwestern British Columbia, discusses the challenges associated with identifying active and potentially active faults in the Lower Mainland, and describes local shallow-crustal faults with particular emphasis on faults thought to exist near Burnaby Mountain. The purpose of this letter is to describe the state of knowledge of shallow-crustal faulting around the Lower Mainland, and specifically, Burnaby Mountain. This letter also highlights the uncertainty and challenges associated with past interpretations and ongoing research.

The term “active” is used extensively to describe faulting and requires proper definition. An “active” fault is one for which rupture is possible given the present-day tectonic and geological setting. No relationship is implied between activity and earthquake recurrence or magnitude. However, it is generally understood that faults which have ruptured recently are more likely to rupture again, unless the tectonic or geological setting has changed significantly. For example, the State of California defines an active fault as one that has ruptured during the Holocene (within approximately the past 11,000 years), as opposed to a potentially active fault which has ruptured during the Quaternary (within approximately the past 1.6 million years) (Bryant and Hart 2007). In general, a fault with evidence of Holocene activity presents more of a rupture hazard than a significantly older fault, because it is more likely that the tectonic stresses causing that rupture continue to develop.





2.0 REGIONAL TECTONIC SETTING AND KNOWN ACTIVE FAULTS

The Cascadia subduction zone is a major tectonic plate boundary that follows the west coast of North America between northern California and Vancouver Island. Along this boundary, the Juan de Fuca oceanic plate is being thrust northeastward beneath the North American continental plate. In response, a complex deformation front has formed within the Cascadia forearc, the area between the offshore plate boundary and the inland Cascade Mountains volcanic arc. Deformation of the forearc includes northwesterly translation of California, clockwise rotation of coastal Oregon, and northwest-directed compression of western Washington and southwestern British Columbia against the Canadian Coast Mountains buttress (Wells et al. 1998; McCaffrey et al. 2007). Approximately 9 mm per year of compression is accommodated by permanent crustal deformation (faults and folds) between Olympia, Washington, and southwestern British Columbia (Wells et al. 1998; Kelsey et al. 2012).

The northern limit of forearc deformation is uncertain. Lidke et al. (2003) suggested that the Devil’s Mountain fault zone, located approximately 70 km south of the US-Canada border, marked the northern limit of deformation (Figure 1). More recently, Holocene offsets were confirmed along the Boulder Creek fault, which lies about 10 km south of Sumas, Washington (Haugerud et al. 2005; Barnett 2007; Barnett et al. 2006, 2007; Siedlecki and Schermer 2007). Kelsey et al. (2012) also identified three faults near Bellingham, Washington: the Birch Bay, Sandy Point and Drayton Harbor faults. These faults have repeatedly offset Holocene sediments and approach within 5 km of the US-Canada border. Kelsey et al. (2012) also proposed that the northern limit of crustal deformation could extend through the Georgia Basin to the northern side of the Fraser Valley and Metro Vancouver.

3.0 HISTORICAL GEOLOGIC INTERPRETATIONS OF FAULT AND LANDSLIDE FEATURES AROUND BURNABY MOUNTAIN

Although many Quaternary faults in the U.S have been well documented, there is very little information available on Quaternary faults in southwestern British Columbia. Unlike the United Stated Geological Survey (USGS) the Geological Survey of Canada (GSC) has not developed a Quaternary fault database. However, since the 1920s, and perhaps earlier, geological investigations have identified discontinuities. Historically, both faulting and landslide activity have been proposed as possible explanations for the discontinuities. The following discussion summarizes investigations, maps and reports which have identified possible faults in the Lower Mainland, with a particular emphasis on proposed faults on or near Burnaby Mountain, and is presented chronologically with reference to Figure 1.

Burnaby Mountain rises to 403 m above sea level and covers an area of approximately 10 square kilometres. Burnaby Mountain is underlain by layers of conglomerate, sandstone, siltstone and shale deposited in the Georgia Basin during the Eocene (36 - 45 million years). Burnaby Mountain is a remnant of a vast alluvial plain that once covered the area. Uplift of the Coast Mountains approximately 5 million years ago triggered erosion of weaker materials





such as shale, and leaving behind stronger materials such as the conglomerate which formed Burnaby Mountain (Armstrong 1990).

Since 1923, multiple sources have discussed discontinuities located on or near Burnaby Mountain. In some cases, the discontinuities were considered faults, and in other reports, the discontinuities were considered landslide features.

In 1923, Johnston illustrated on a map an east-to-west-trending fault within Burrard Inlet, approximately 1.5 km north of Burnaby Mountain. Johnston (1923) stated explicitly that no faults had actually been observed; however a fault was inferred to explain the unconformity between sedimentary and intrusive rocks exposed on the south and north sides of Burrard Inlet respectively.

Webster (1958) produced a report for the B.C. Department of Highways that interpreted the geology of the north slope of Burnaby Mountain as a slide in Tertiary bedrock. In this report, tension cracks were described around the slide crown and continuous scarps in the ground around its flanks. Problems with buildings and infrastructure reported by several local agencies and utilities were interpreted as evidence for ongoing landslide movement (Webster 1958). These included:

Difficulty maintaining alignment and grade of a steel water main in the slope maintained by the Municipality of Burnaby;

The Battrum House, a school building located within the slide area, was displaced, damaged and later abandoned in the wake of permanent ground displacement possibly exacerbated by the 1947 Vancouver Island earthquake;

Shell Oil Company abandoned plans for a large installation in the area due to unstable soil conditions;

TransMountain Pipelines cancelled plans for an installation after studying the area; The Department of Highways experienced maintenance problems due to settling and

cracking of the road surface; and Frequent maintenance had been required to maintain track grade on the Canadian

Pacific Railway at the foot of Burnaby Mountain.

Webster (1958) concluded that excess pore water pressures related to high rainfall, natural changes in drainage patterns and breaks in the Burnaby water line were periodically triggering local reactivation within the landslide. No mention of faulting was made anywhere in Webster’s (1958) report.

In 1965, the GSC published a geological map of the Coquitlam area based on work by Roddick completed between 1950 and 1952. This map depicted an ‘approximate’ fault trending east-to-west across Burnaby Mountain, coincident with the scarp of the steep north face identified by Webster (1958). The map did not depict Johnston’s (1923) inferred fault in Burrard Inlet. Roddick (1965) did not explicitly describe the geological evidence used to infer the fault mapped on Burnaby Mountain.





In 1971 Blunden produced a report summarizing the geology of Vancouver’s ‘Downtown Coal Peninsila’, an area which currently includes downtown Vancouver and Stanley Park. In this report Blunden identified several possible faults in the area, including faults in Burrard Inlet, along Hastings Street and in the Lost Lagoon area. According to Blunden (1971) these faults were inferred based on local geological information including boreholes and excavations, natural exposures and personal recollections. The report stated that some faults showed evidence of ‘recent’ local activity but also specified that movement likely occurred before 6,500 years ago. Blunden (1971) also reported that a small earthquake occurred on February 19, 1938 with an epicenter beneath Burrard Inlet. The faults reported by Blunden (1971) were not referenced in later publications discussing faulting in southwestern British Columbia.

Blunden (1975) later described the historical geology of the lower Fraser River valley, including evidence for additional historical earthquakes. Blunden (1975) reports that in February 1859, Colonel R.C. Moody produced a sketch map of the Vancouver area showing Stanley Park as an island. In June 1859, Captain G.H Richards surveyed Burrard inlet and mapped Stanley Park as a peninsula. Blunden accounted for this discrepancy by suggesting that an earthquake might have occurred at some time between February and June 1859, and that this earthquake uplifted the Stanley park area by at least 2.5 m, enough to expose the lowest-elevation point on the peninsula around present-day Lost Lagoon. However, no such event is described in any other historical records, even though an earthquake large enough to cause this much uplift would have been noted in the historical record. Furthermore, many other plausible explanations can be invoked to explain the map discrepancy; in particular, it is possible that Colonel Moody failed to entirely circumnavigate Stanley Park and simply assumed it was an island.

Crampton (1980s, actual date unknown) summarized the detailed stratigraphy and structural geology of Burnaby Mountain. Four north-to-south-trending normal faults were inferred from bedrock outcrops and geomorphic patterns mapped in the early 1980s, and rock core logs dating from the 1920s (Crampton, 1980s). None of the faults mapped by Crampton were coincident with, or oriented parallel to, the east-to-west trend of Burnaby Mountain’s steep north flank.

Armstrong (1990) described block slides of several million tonnes of sedimentary rocks on the steep north side of Burnaby Mountain. Armstrong (1990) suggested that construction of the Canadian Pacific Railway and Barnet Highway at the base of the slope reactivated parts of the slide mass. Armstrong (1990) did not map faults near Burnaby Mountain or within Burrard Inlet.

Turner et al. (1998) produced ‘Geomap Vancouver’, a geological map covering the Vancouver metropolitan area. This map showed a fault traversing the north slope of Burnaby Mountain, roughly coincident with Roddick’s (1965) approximate fault and approximate location of Webster’s (1958) slide crown. The fault, and evidence supporting a fault interpretation, was not explicitly described.





4.0 CHALLENGES IN LOWER MAINLAND FAULT STUDIES

Two approaches are broadly employed to identify active or potentially active shallow-crustal faults; through paleoseismology, and studying fault behaviour. Paleoseismology, the direct observation of faults or other features generated by earthquakes, can be employed to determine the frequency and magnitude of past ruptures. Fault behavior and activity may also be inferred from the record of historical earthquakes captured by seismic monitoring networks.

Paleoseismologic methods have limitations when applied in the Lower Mainland. Repeated advances and retreats of Cordilleran ice sheets have removed or masked much of the evidence for Quaternary (< 1.6 million years) faulting. The last retreat of the Fraser glaciation from the Lower Mainland began about 12,000 years ago and postglacial sediments, including the thick Fraser Delta deposits, have continued to cover the lowlands to the present day (Armstrong 1990). This relatively recent deposition of surficial materials precludes identification of fault-line scarps created by earthquakes and therefore impedes the identification of fault traces based on surface mapping. However, the use of high-resolution LiDAR (Light Detection and Ranging) may help identify subtle fault features in these conditions (e.g. Barnett 2007; Kelsey et al. 2012). Some information about the recurrence and magnitude of larger events can be inferred from deposits of earthquake-generated slope or submarine mass flows (e.g. Goldfinger et al. 2003; Blais-Stevens et al. 2012); however, it is usually difficult to relate earthquakes to specific structures.

The location, orientation and sense of slip on active earthquake-source faults can be inferred from clustered or aligned historical earthquake hypocentres. The seismic monitoring network in place over the past 40 years around southwestern British Columbia can resolve earthquake hypocentres to within a few kilometres horizontally and vertically (Rogers 1994). However, attempts to correlate historical seismicity to known shallow-crustal structures (e.g. Rogers 1994; Mulder and Rogers 2002) have been unsuccessful to date.

A key limitation of the local historical earthquake catalogue is its short duration. Few earthquakes that pre-date European settlement are known, and a relatively robust seismic monitoring network has only been in place for a few decades. Locations and magnitudes of events that pre-date the network are necessarily approximate. The short record is also unlikely to have captured the range of events that are possible in the region, especially considering that large events may have long recurrence intervals.





5.0 CONCLUSIONS

Although many researchers have invoked faults to explain geological discontinuities around Burnaby Mountain, there is not enough evidence to conclude that the faults purported to exist are real or active. At present, there are no known active faults in the Lower Mainland. However, to state that active shallow-crustal faults are conclusively absent, is false. The absence of known active faults is due to the absence of evidence, but not evidence of absence. The body of evidence produced by the geologic community working around the Lower Mainland is not robust enough to support the conclusion that active faulting is not present. Recent work in the U.S. has revealed active faults within 5 km of the international border. It is entirely plausible that, given comparable research effort, active faults could be found north of the border. Active shallow-crustal faulting is certainly not precluded by our understanding of the regional tectonic setting.

The proposition that the north flank of Burnaby Mountain is the locus of a potentially active fault is variably supported, refuted and not addressed by the interpretations of past geological work and historical accounts. It is unfortunate that most of the geological interpretations do not explicitly describe or illustrate the evidence used to support them. However, there is enough uncertainty and plausible alternatives to suggest that the active-fault interpretation is doubtful, and the probability of impact to Kinder Morgan Canada’s (KMC’s) facilities specifically from surface rupture or strong ground motions generated from this feature is low. To better constrain our understanding of the geologic processes and hazards present around Burnaby Mountain (from both seismic and other sources) and the potential effect of those hazards on KMC facilities, further geological and geotechnical investigation is required. These investigations will be conducted as part of the detailed design phase of the TransMountain Expansion Pipeline (TMEP) project, and would include bedrock and surficial geological mapping, a compilation of historical geological and geotechnical information around the study area, the use of available surface and subsurface imaging technology such as LIght Detection and Ranging (LIDAR) and geophysics, and other techniques.





REFERENCES

Armstrong, J.E. 1990. Vancouver Geology. Edited by Charlie Roots and Chris Staargaard. Geological Association of Canada - Cordilleran Section. 128 p.

Barnett, E.A. 2007. Active faulting at the northern margin of the greater Puget lowland: A paleoseismic and magnetic-anomaly study of the Kendall fault scarp, Whatcom County, northwest Washington. Master’s thesis presented to the Faculty of Humboldt State University.

Barnett, E.A., Kelsey, H.M., Sherrod, B.L., Blakely, R.J., Hughes, J.F., Schermer, E.R., Haugerud, R.A., Weaver, C.S., and Siedlecki, E. 2006. Active faulting at the northeast margin of the greater Puget Lowland—A paleoseismic and magnetic-anomaly study of the Kendall Scarp, Whatcom County, northwest Washington. Eos, Transactions, American Geophysical Union, v. 87, Abstract S31A-0183.

Barnett, E.A., Kelsey, H.M., Sherrod, B., Blakely, R.J., Hughes, J., Schermer, E.R., Haugerud, R.A., Weaver, C., Siedlecki, E.M., and Blakely, R.J. 2007. Active faulting at the northeast margin of the greater Puget Lowland; a trenching and wetland coring study of the Kendall Fault scarp, Whatcom County, northwest Washington. Geological Society of America Abstracts with Programs, v. 39, p. 61.

Blais-Stevens, A., Rogers, G.C. and Clague, J.J. 2011. A Revised Earthquake Chronology for the last 4,000 Years Inferred from Varve-Bounded Debris-Flow Deposits beneath an Inlet near Victoria, British Columbia. Bulletin of the Seismological Society of America, vol. 101, no. 1, pp. 1-12.

Blunden, R.H. 1971. Vancouver’s downtown (coal) peninsula – urban geology: B.Sc. Thesis (Publ.), Dept. of Geology, University of British Columbia, 53 p. 22 Figures.

Blunden, R.H. 1975. Historical Geography of the Fraser River. Adventures in Earth Science Series Number 3. A Contribution of the Pacific Earth Science Methods Workshop, UBC.

Bryant, W.A., and Hart, E.W. 2007. Fault-rupture hazard zones in California—Alquist-Priolo Earthquake Fault Zoning Act with index to Earthquake Fault Zone maps. California Department of Conservation, California Geological Survey, Special Publication 42.

Crampton, C.B. 1980s. Natural science studies of Burnaby and Belcarra mountains. Simon Fraser University Discussion Paper No. 8.

Dunphy, M. December 13, 2012. Waves, plates and earthquakes on B.C.’s West Coast. Georgia Straight, p. 15.

Goldfinger, C., Nelson, C.H., and Johnson, J.E. 2003. Holocene earthquake records from the Cascadia subduction zone and northern San Andreas Fault based on precise dating of





offshore turbidites. Annual Review of Earth and Planetary Sciences, vol. 31, no. 1, pp. 555-577.

Haugerud, R.A., Sherrod, B.L., Wells, R.E., Hyatt, T., 2005, Holocene displacement on the Boulder Creek Fault near Bellingham, WA and implications for kinematics of deformation of the Cascadia Forearc: Geological Society of America Abstracts with Programs, v. 37, p. 476.

Johnston, W.A. 1923. Geology of the Fraser River Map Area. Geological Survey of Canada, Memoir 135, 87 p. with map. Kelsey, H.M., Sherrod, B.L., Blakely, R.J. and Haugerud, R.A. 2012. Holocene faulting in the Bellingham forearc basin: Upper-plate deformation at the northern end of the Cascadia subduction zone. Journal of Geophysical Research, vol. 117.

Lidke, D.J., Johnson, S.Y., McCrory, P.A., Personius, S.F., Nelson, A.R., Dart, R.L., Bradley, Lee-Ann, Haller, K.M., and Machette, M.N. 2003. Map and data for Quaternary faults and folds in Washington State: U.S. Geological Survey Open-File Report 03-428, 15 p., 1 pl., scale 1:750,000, http://earthquake.usgs.gov/hazards/qfaults/. Fault data updated November 3, 2010. McCaffrey, R.A., Qamar, I., King, R.W., Wells, R., Khazaradze, G., Williams, C.A., Stevens, C.W., Vollick, J.J. and Zwick, P.C. 2007. Fault locking, block rotation and crustal deformation in the Pacific Northwest, Geophys. J. Int., vol. 169, no. 3, pp. 1315–1340.

Mulder, T.L. and Rogers, G.C. 2002. Seismicity in the vicinity of the Leech River fault. Seismological Research Letters, v. 73, no. 2, p. 240.

Roddick, J.A. 1965. Vancouver north, Coquitlam and Pitt Lake map areas, British Columbia, with special emphasis on the evolution of the plutonic rocks. Geological Survey of Canada, Memoir 335.

Rogers, G. C. 1994. Earthquakes in the Vancouver area, in Geology and Geological Hazards of the Vancouver Region, Southwestern British Columbia, edited by J. W. H. Monger, GSC Bulletin 481, pp. 221-229.

Siedlecki, E.M., and Schermer, E.R. 2007. Paleoseismology of the Boulder Creek fault, Kendall, WA. Geological Society of America Abstracts with Programs, v. 39, p. 26.

Turner, R.J.W., Clague, J.J., Groulx, B.J. and Journeay, J.M. 1998. GeoMap Vancouver, Geological Map of the Vancouver Metropolitan Area. Geological Survey of Canada Open File 3511.

Webster, A.T. 1958. Report on Hastings Barnet Slide Vicinity STA. 216 and CPR Mile 120.3 Cascade Subdivision. Province of British Columbia, Department of Highways, Materials Testing, Research and Development Branch.





Wells, R.E., Weaver, C.S., and Blakely, R.J. 1998. Forarc migration in Cascadia and its neotectonic significance. Geology, vol. 26, pp. 759-763.

450000

450000

500000

500000

550000

550000

600000

600000

650000

650000

5350

000

5350

000

5400

000

5400

000

5450

000

5450

000

LEGENDMAPPED FAULTMAPPED DISCONT INUIT YA DISCONT INUIT Y IS A LINEAMENT ORSUR FACE T HAT INDICAT ES A CHANGE INMAT ER IAL PR OPER T IES. DISCONT INUIT IESCAN R EFLECT DEPOSIT ION, SLOPEINST ABILIT Y OR FAULT ING, AMONG OT HERCAUSES.

10,000 0 10,000 20,000 30,000

MET R ES

1:650000SCALE

PR OJECT :

T IT LE:

PR OJECT No.: FIG No.: R EV.:

FAULT S IN T HE LOWER MAINLAND

OVER VIEW MAP OF MAPPED FAULT S AND DISCONT INUIT IES

0095150 01CLIENT :

KINDER MOR GAN

B G C B G C E N G IN E E R IN G IN C .AN APPLIED EAR T H SCIENCES COMPANY

SCALE:

DAT E:

DR AWN:

DESIGNED:

CHECKED:

APPR OVED:

PR OFESSIONAL SEAL:1:650,000JAN 2013

LL

KVEKVE

ABR EV. DAT E R EVISION NOT ES DR AWN CHECK APPR .

AS A MUT UAL PR OT ECT ION T O OUR CLIENT , T HE PUBLIC, AND OUR SELVES, ALL R EPOR T S AND DR AWINGS AR E SUBMIT T ED FOR T HE CONFIDENT IAL INFOR MAT ION OF OUR CLIENT FOR A SPECIFIC PR OJECT . AUT HOR IZAT ION FOR ANYUSE AND/OR PUBLICAT ION OF T HIS R EPOR T OR ANY DAT A, ST AT EMENT S, CONCLUSIONS OR ABST R ACT S FR OM OR R EGAR DING OUR R EPOR T S AND DR AWINGS, T HR OUGH ANY FOR M OF PR INT OR ELECT R ONIC MEDIA, INCLUDINGWIT HOUT LIMIT AT ION, POST ING OR R EPR ODUCT ION OF SAME ON ANY WEBSIT E, IS R ESER VED PENDING BGC’S WR IT T EN APPR OVAL. IF T HIS R EPOR T IS ISSUED IN AN ELECT R ONIC FOR MAT , AN OR IGINAL PAPER COPY IS ON FILEAT BGC ENGINEER ING INC. AND T HAT COPY IS T HE PR IMAR Y R EFER ENCE WIT H PR ECEDENCE OVER ANY ELECT R ONIC COPY OF T HE DOCUMENT , OR ANY EXT R ACT S FR OM OUR DOCUMENT S PUBLISHED BY OT HER S.

X:\Pr

ojects

\0095

\150\W

orksp

ace\2

0130

111_

REPO

RT_F

aults

_In_T

he_L

ower_

Mainl

and\0

1_Ov

erview

_Map

_of_M

appe

d_Fa

ults_

and_

Disco

ntinu

ities.m

xd

FIG T O BE R EAD WIT H BGC R EPOR T T IT LED "FAULT S IN T HE LOWER MAINLAND" DAT ED JANUAR Y 2013

³

NAD 1983 UT M Zone 10N

504000

504000

506000

506000

5458

000

5458

000

5460

000

5460

000SEE INSET MAP 2 INSET MAP 2

1:50000SCALE

³488000

488000

490000

490000

492000

492000

5458

000

5458

000

5460

000

5460

000

5462

000

5462

000

SEE INSET MAP 1

INSET MAP 1

SCALE1:50000

³

#800-1045 howe street - · pdf file#800-1045 howe street vancouver, b.c. canada v6z 2a9 ......

Documents