Liquefaction Susceptibility Mapping in Boston, Massachusetts

Liquefaction Susceptibility Mapping in

Boston, Massachusetts

CHARLES M. BRANKMAN1

William Lettis & Associates, Inc., 1777 Botelho Drive, Suite 262,Walnut Creek, CA 94596

LAURIE G. BAISE

Department of Civil and Environmental Engineering, Tufts University,113 Anderson Hall, Medford, MA 02155

Key Terms: Liquefaction, Seismic Hazards, Engineer-ing Geology, Geotechnical, Surficial Geology

ABSTRACT

The Boston, Massachusetts, metropolitan area hasexperienced several historic earthquakes of aboutmagnitude 6.0. A compilation of surficial geologicmaps of the Boston, Massachusetts, metropolitan areaand geotechnical analyses of Quaternary sedimentarydeposits using nearly 3,000 geotechnical borehole logsreveal varying levels of susceptibility of these units toearthquake-induced liquefaction, given the generallyaccepted design earthquake for the region (M6.0 with0.12g Peak Ground Acceleration (PGA)). The majorityof the boreholes are located within the extensivedowntown artificial fill units, but they also allowcharacterization of the natural deposits outside thedowntown area. The geotechnical data were comple-mented with surficial geologic mapping, combiningpublished and unpublished geologic maps, aerialphotographic interpretation, and soil stratigraphy datafrom an additional 12,000 geotechnical boring logs.Susceptibility maps were developed based on liquefac-tion-triggering threshold ground motions, which weredetermined using the borehole data. We find that muchof the non-engineered artificial fill that underlies thedowntown Boston area is, when saturated, highlysusceptible to liquefaction during seismic loading.Holocene alluvial and marsh deposits in the regionare also moderately to highly susceptible to liquefac-tion. Much of the outlying area is underlain byPleistocene and Quaternary glacial and glaciofluvialdeposits, which have low to moderate susceptibility toliquefaction. This study provides data needed toeffectively manage liquefaction hazards in the Boston

area, and it will assist in characterizing seismichazards, mitigating risks, and providing informationfor urban planning and emergency response.

INTRODUCTION

Boston, Massachusetts, is located in a region ofmoderate historic seismicity, where several historicalevents of about M6.0 have occurred (e.g., 1727, 1755).The possibility therefore exists for the generation ofearthquake-induced liquefaction of near-surface sedi-ments in the Boston area. In this paper, we presentresults of a study to assess the liquefaction suscepti-bility of natural sediments and areas of artificial fill inthe Boston metropolitan area, with the aim ofcharacterizing liquefaction hazard and providinginformation to local communities for improvedplanning and mitigation strategies. The primary goalof the study was to develop liquefaction susceptibilitymaps by combining surficial geologic mapping withsubsurface borehole data. To develop these maps,existing surficial geologic maps at various scales wereaugmented with field reconnaissance mapping toprovide a base for assessing the properties of thegeologic units. An extensive digital borehole databasewas compiled to provide data on the subsurfaceproperties; it is composed of nearly 3,000 borings, andit focuses on the artificial fill units in downtownBoston but also provides coverage of the othergeologic units. The subsurface properties, includingsoil type, standard penetration test blow counts, andestimated fines content, were used to determineliquefaction susceptibility of each individual samplein the database. The liquefaction susceptibilitymapping used the results of both the surficial geologicmapping and the subsurface sample liquefactionsusceptibility analysis.

The study area encompasses eight 1:24,000-scale(7.5 minute) quadrangles in the metropolitan Bostonregion, and it includes the downtown Boston area and

1Present address: Department of Earth and Planetary Sciences,Harvard University, 20 Oxford Street, Cambridge, MA 02138; phone:617-495-0367; fax: 617-495-7660; email: [email protected].

Environmental & Engineering Geoscience, Vol. XIV, No. 1, February 2008, pp. 1–16 1

surrounding communities (Figure 1). Much of theregion is underlain by Pleistocene and Quaternaryglacial till and glaciofluvial deposits, as well as largeareas of marsh deposits and extensive regions of non-engineered artificial fill. Based on their compositionand conditions of geologic deposition, glaciofluvialdeposits, marsh deposits, and especially the non-engineered artificial fill are potentially susceptible toliquefaction during large earthquakes.

BACKGROUND

Seismic History

The Boston region has experienced several historicearthquakes that have caused ground motions signif-icant enough to trigger liquefaction in susceptiblesediments. In 1638, an earthquake thought to havebeen located in central New Hampshire struck witha magnitude (MbLg) of about 6.5; Ebel (1996, 1999)estimated that the event produced modified Mercalliintensity (MMI) of V–VII in Boston. An earthquakein 1663 located within the Charlevoix seismic zone in

southern Quebec had a magnitude of about 7.0 andcaused ground shaking intensity in Boston of at leastV–VI, resulting in damage to several chimneys in theBoston area (Crosby, 1923; Ebel, 1996). The 1727Newbury earthquake occurred approximately 56 kmnortheast of Boston, with an estimated momentmagnitude (Mw) of 5.6, a reported local MMI ofVI–VII, and a MMI for Boston and northern suburbsof V–VI (Ebel, 2000). Reports in Newbury at the timeof the earthquake describe sand boils, which indicateliquefaction (Plant, 1742; Ebel, 2000). These occur-rences of liquefaction have been confirmed bypaleoseismic studies, which found sand dikes andsills in glaciomarine sediments in two locationscorresponding to the liquefaction during the 1727earthquake and one prehistoric event (Tuttle andSeeber, 1991; Tuttle et al., 2000).

The 1755 Cape Ann earthquake was the largestearthquake to have affected Boston in historic times,and it caused damage throughout eastern Massachu-setts and was felt along the eastern seaboard of NorthAmerica from Nova Scotia to South Carolina (Ebel,2006). The earthquake was located approximately

Figure 1. Quadrangle outline map of the greater Boston region showing community boundaries.

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2 Environmental & Engineering Geoscience, Vol. XIV, No. 1, February 2008, pp. 1–16

40 km ENE of Cape Ann, Massachusetts, and it hada Mw of about 5.9 (Ebel, 2006). The earthquakecaused extensive damage in Boston, destroying atleast 1,500 and as many as 5,000 chimneys (Whitman,2002), and it reportedly affected water levels in wellsas far away as central and western Connecticut(Thorson, 2001). Crosby (1923) estimated that the1755 earthquake caused a MMI of IX in Boston,while Ebel (2006) estimated a MMI of VII. Estimatesof ground motions in Boston range from 0.08 to 0.12g(Ebel, 2006). Written accounts of damage caused bythe 1755 earthquake in Scituate, about 30 kmsoutheast of Boston, reported liquefaction sand boils;these features were investigated using paleoseismicand geophysical techniques, but the studies were notconclusive (Tuttle et al., 2000).

Liquefaction Hazard Mapping

Regional liquefaction hazard mapping projectshave predominantly relied on criteria that relateQuaternary surficial deposits to liquefaction suscep-tibility, taking into account factors such as deposi-tional environment, dominant grain size, and relativeage (Youd and Perkins, 1978). This methodologycommonly leads to the identification of large regionsof susceptible material. Youd and Perkins (1987)discussed how the resulting maps show geologic unitsthat likely contain liquefiable sediments but do notidentify the precise location of the liquefiablesediments within the geologic unit. Therefore, it ispossible that within a susceptible unit only a smalldiscrete area or areas will actually liquefy duringa given earthquake.

Recent liquefaction mapping projects have typical-ly included the concurrent collection of subsurfacedata to provide more quantitative susceptibilityestimates. The subsurface data may include standardpenetration test N-values, cone penetrometer (CPT)data, shear-wave velocity (Vs), soil descriptions(including grain-size distributions), stratigraphy, andgroundwater measurements. Hitchcock et al. (1999)conducted extensive investigations of liquefactionhazards and produced detailed susceptibility mapsin Simi Valley, California, using surficial geologicmapping and analysis of over 1,000 boring logs froma variety of Quaternary deposits. Hitchcock andHelley (2000) collected over 1,600 boring logs for 127.5-minute quadrangles in the Santa Clara Valley,California. The boring logs were used to helpdelineate the top of the Pleistocene deposits, estimatethe thickness of Holocene sediments, and determinethe thicknesses and time of placement of artificial fills.Monahan et al. (2000) produced relative liquefactionhazard maps for Victoria, British Columbia, from

interpretations of stratigraphy derived from over5,000 boring logs. The hazard classification for theVictoria maps was based on an interpretation of thestratigraphy represented in the boring logs anda detailed analysis of 31 sites. The detailed analysisconsisted of a combination of a probabilistic pre-diction of liquefaction using the Seed and Idriss(1971) simplified approach and a probability ofliquefaction severity index, which depends on depthand thickness of the liquefiable materials (Monahanet al., 1998, 2000).

Recently, the California Geological Survey (CGS)has produced seismic hazard zone maps that delineateareas that are likely to contain liquefiable sedimentsin seismically active areas of the state. The CGSzonation is based on susceptibility evaluations thatuse geologic criteria and borehole analyses similar tothe method used in this study. To date, CGS hascompiled Quaternary geology for 113 U.S. GeologicalSurvey (USGS) 7.5-minute quadrangles and hascollected and analyzed over 16,000 borehole logsfrom the greater Los Angeles and San Francisco Bayarea (California Geological Survey, 2007).

METHODOLOGY

We applied regional-scale liquefaction mappingcriteria based on surficial geology and analysis ofgeotechnical data to prepare liquefaction hazardmaps for the greater Boston metropolitan region.The mapping criteria consisted of three hazard classes(low, moderate, and high), which refer to varyingextents of expected liquefaction. Our intent was toprovide classes of hazard based on both geologic andgeotechnical criteria that account for the variability ofgeologic materials as well as the distribution ofliquefiable materials within an individual geologicunit.

Surficial Geologic Maps

Surficial geologic maps of eight 1:24,000-scalequadrangles (Figure 1) were compiled from existingpublished geologic maps, where available, and thesewere augmented with reconnaissance field mappingthroughout the study area. High-quality, large-scale,published maps were available for the Norwood(Chute, 1966) and Blue Hills (Chute, 1965) quad-rangles, and for portions of the Boston North andLexington quadrangles (Chute, 1959). Smaller-scalemaps of the entire study area were available (e.g.,Kaye, 1978; Thompson et al., 1991; and Woodhouseet al., 1991) and provided a first-order base map foruse in field checking.

Boston Liquefaction Susceptibility Maps


In the mapping, we faced two primary challenges.First, the area is extensively developed; exposure istypically less than one to two percent, and there hasbeen large modification of the land surface through-out the study area. Extensive grading for construc-tion, draining and filling of wetlands and marshes,channeling and diversion of streams and rivers, andmodification of river banks have occurred over thepast three centuries. These cultural processes oftenobscure the nature of the underlying deposits, andthey occur not only in the densely populateddowntown Boston and surrounding urban areas, butalso in the outer suburban regions. This difficultydirectly affected the level of detail that could beattained in subdividing units during the surficialmapping. Second, previous workers mapping theregion over the past century have adopted a varietyof classification schemes for the surficial geologicunits. This can be attributed to both the developmentof the science of glacial and Quaternary geology overthe past century and also the wide variety of scales ofmapping and the various locales that were the focusof the mapping projects.

We addressed these issues by using generalizedgeologic units based on those defined by Chute (1965,1966). We divided surficial units into six general units,including glacial drumlins (glacial till), glacial groundand end moraines (glacial till), glaciofluvial deposits(glacial outwash plains, eskers, kames, and kamefields), marsh deposits, beach deposits, and historicartificial fill. These units, while general, groupdeposits based on common depositional processes,composition, and age, and they are present through-out the study area. In addition, these units formrelatively distinct geomorphological terrains and canbe identified with confidence on the basis of theirsurface expression. This allowed us to map geologicunits even with the lack of exposures describedpreviously. Admittedly, there is variability of geologicproperties within each unit, and in some cases, ourmorphology-based mapping may have passed oversome of the details of the contacts between adjacentmap units. However, given the challenges imposed bythe issues as described here, we feel that these unitdesignations do not introduce substantial error intothe mapping and provide a good base map for theliquefaction analyses.

Validation and confirmation of our mapping wereaccomplished by performing reconnaissance mappingof portions of quadrangles with published surficialgeologic maps prior to examination of those pub-lished maps and then comparing the interpretationsbetween the maps. In all cases, our reconnaissancemapping provided good agreement with the publishedmaps. In addition, published maps from adjacent

quadrangles (e.g., the Reading quadrangle; Oldale,1962) allowed us to check geologic contacts along thequadrangle boundaries. Finally, and importantly, wewere able to confirm the map units and refine unitcontacts using data from the borehole database andthe larger database of borings from the MassachusettsWater Resources Authority.

Geotechnical Borehole Database

Data for this project were acquired from severalsources. An electronic collection of data (1,905borings) was acquired from the Central/ArteryTunnel project in Boston through the MassachusettsWater Resources Authority (MWRA). This databasewas modified from the original to fit into a standardformat. Geologic descriptions varied considerablyand were therefore simplified to be more consistentthroughout the region, though sample informationwas not altered. In addition, electronic scannedimages of 12,782 boring logs and their locationcoordinates were acquired from the MWRA. Due tothe large number of these data, we selected boringsfrom this set to fill coverage gaps in the other boringdatabases. Data from 119 of these boring logs werehand-entered into the database. Additional MWRAlogs were examined as needed for the surficialgeologic mapping and assessment of map unitboundaries. The Boston Society of Civil Engineers(BSCE, 1969) collection of borings was also used asa data source, and 314 borings from the BSCEcollection were hand-entered into the database.Finally, for the Cambridge area, 715 borings werecollected in and near the Cambridge fill unit along thenorthern shore of the Charles River. The resultinggeotechnical database from all of the aforementionedsources includes 2,963 borings.

Data from geotechnical borings were entered intoan electronic database in order to facilitate relationaldatabase management and allow for the flexibility ofdata input. The database includes both general andgeologic information gathered from subsurface ex-plorations, such as project and drilling information,date and depth of boring, ground surface elevation,depth to groundwater, depths and descriptions ofstratigraphic units and samples, standard penetrationtest (SPT) N-values, and x-y coordinate values. Thesoil samples were characterized by soil type (i.e., sand,silt, silty sand, clay, etc.) and a detailed sampledescription. When available on the original boringlog, stratigraphic unit was also associated withindividual soil samples. The stratigraphy was charac-terized by geologic unit and depth to top and bottomof each unit. In some cases, the stratigraphic unit was

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modified slightly from the original boring log in orderto conform to a uniform naming convention.

Quantitative Analysis

Liquefaction susceptibility refers to the relativeresistance of soils to loss of strength due to anincrease in pore-water pressure caused by groundshaking. The degree of resistance is governedprimarily by the soil’s physical properties such asgrain size, density, and saturation. Zones correspond-ing to areas of very low to very high susceptibility canbe defined based on a liquefaction-triggering thresh-old analysis using standard penetration test (SPT)data in areas with borehole data, and with criteriabased on the deposit’s age, texture, and groundwatercondition in areas lacking borehole data.

Where borehole data were available, liquefactionsusceptibility was quantified according to the adjust-ed SPT blow count (N1)60 values. This quantitativeevaluation of liquefaction susceptibility was based onthe Seed-Idriss simplified procedure, which wasreviewed and updated in a workshop report summa-rized by Youd et al. (2001). This procedure calculatessoil resistance to liquefaction, expressed in terms ofcyclic resistance ratio (CRR), based on SPT data,groundwater level, soil density, percent fines, andsample depth. The groundwater levels in Boston arehighly locally variable as a result of sewer systems,dewatering projects, and seasonal variations. We usedgroundwater data where noted in the boring logs;otherwise, we used a conservative groundwater levelat the ground surface. CRR values were compared tocyclic shear stresses generated by the estimatedground motions, expressed in terms of cyclic stressratio (CSR). Appropriate correction factors for SPTvalues, and scaling factors for fines content andearthquake magnitude (see following), were appliedas suggested in Youd et al. (2001). For each soilsample in the database, a liquefaction trigger level ofthe peak ground acceleration (PGAtrigger) was calcu-lated using the simplified Seed-Idriss approach (Youdet al., 2001), as described already, which takes intoaccount depth, saturation, soil type, density, and finescontent. A factor of safety (FS) equal to 1.2, whichhas been recommended to achieve a 20 percentprobability of liquefaction (Juang et al., 2002), wasused in the calculations. Thus, we calculated thePGAtrigger for each soil sample in the database, whichallowed us to provide individual classifications ofsusceptibility. These susceptibility category values aredistinct from the geologically determined criteriabecause they are specific to an individual soil samplerather than the entire geologic unit. This allows

characterization on two scales: regionally, based onsurficial geologic unit, or locally, based on SPT data.

We used a design earthquake of Mw 5 6.0 for thescaling factors used in the trigger-level calculations toassess the liquefaction susceptibility, based on thehistoric earthquake record and, specifically, themagnitude of the 1755 Cape Ann event (see previous).In addition, we selected a PGA of 0.12g as our designground motion for determination of liquefactiontriggering. Using the 2002 and 2007 (proposed)USGS Probabilistic Seismic Hazard Maps, valuesfor two percent in 50 years peak ground accelerationfor Boston match the chosen design value of 0.12g(USGS, 2007). For Boston, the Massachusetts Build-ing Code mandates a peak ground acceleration of0.12g, which is consistent with the standard ofpractice.

In regions where subsurface data were not avail-able, we assessed liquefaction susceptibility usinggeologic criteria as originally defined by Youd andPerkins (1978). These criteria are based on thephysical characteristics of a given geologic unit thatimpact the susceptibility of that unit to coseismicliquefaction, including the depositional environment,age, lithologic composition, grain-size distribution,density, and degree of saturation. While inherentlyqualitative, classifications using these criteria havebeen verified through the response of similar geologicunits to ground motions during recent large earth-quakes, and it is appropriate for regions withoutavailable subsurface data.

Liquefaction Hazard Mapping Methodology

In moving from a local, sample-scale assessment ofliquefaction susceptibility to a regional-scale suscep-tibility map, we used a combined approach using boththe geologic criteria described already and statisticalanalysis of the subsurface data. The statisticalmethodology is described more completely in Baiseet al. (2006), and Table 1 summarizes the liquefactionhazard mapping criteria used in this study.

In the development of the liquefaction hazardmapping criteria, an investigation of populationstatistics was completed for several liquefiable depos-its in the study area. The accuracy of the character-ization depended primarily on the amount of dataavailable. Using liquefaction probabilities instead ofsusceptibility categories, Baise et al. (2006) found thatthe estimated error for the liquefaction probabilityover a subsurface unit was directly related to themean value and the number of samples. Susceptibilityestimates from population percentages based onPGAtrigger values can be misleading when based ona small number of samples from within a given



geologic unit. Therefore, broad regional estimates ofliquefaction susceptibility based on limited samplesresulted in large levels of estimate uncertainty. Ifa sufficient sample density is not available, thecharacterization should rely more heavily on thesurficial geology.

The liquefaction hazard criteria presented here donot describe expected deformations resulting fromliquefaction (i.e., settlements, lateral spreading, etc.),which would depend on thickness of susceptible unit,depth to susceptible unit, lateral extent of susceptibleunit, surface and intra-unit topography, and nearbystructures. Rather, the maps produced using thesecriteria are meant to characterize the spatial extent ofliquefiable materials. In addition, the liquefactionhazard mapping is meant for the regional scale andnot the site-specific scale. This information can beused to plan detailed explorations for a site to confirmthe liquefaction hazard at the site.

SURFICIAL GEOLOGIC MAPPING

Quaternary Geology

The Quaternary geology of the Boston area(Figure 2) is dominated by sediments deposited duringand after extensive and repeated Pleistocene glacia-tions of the area (Kaye, 1982; Barosh et al., 1989; andWoodhouse et al., 1991). Glacial advances depositedtill as drumlins and ground moraines, while glacialwithdrawal during the late Pleistocene deposited largeregions of glacial outwash. The outwash and tilltogether comprise about 75 percent of the surface inthe study area. During and after glaciation, coastalprocesses influenced by the competing effects ofcrustal isostatic rebound and eustatic sea-level changeresulted in a complex distribution of coastal estuarineand tidal marsh sediments. Local beach deposits andtidal estuary deposits developed along active coastalareas and sheltered marshes, respectively. In addition,the Charles River and other smaller rivers (e.g., Mysticand Neponset Rivers) and streams locally deposited

sequences of fluvial sands and overbank silt deposits,which line the margins of the river channels and arenow often present in the subsurface under the artificialfill units along the banks.

Glacial till is mapped as two separate units: glacialdrumlins and ground moraines. Both generally liedirectly on the bedrock surface and were depositedbelow the advancing glaciers or during the melting ofstagnant or receding ice (Chute, 1966). These twounits were differentiated in the mapping on the basisof their differing and unique morphologies. Drumlinsare present throughout the study area, and they havebeen well described in the literature (e.g., Woodhouseet al., 1991). They occur as round to elliptical hills andhighlands generally reaching several tens of metersabove the surrounding terrain. Drumlins are oftencored by local bedrock highs. Prominent drumlinsinclude several in the Somerville-Medford-Charles-town areas north of Boston, and throughout theBoston outer harbor, where drumlins form many ofthe harbor islands. Ground moraines are alsocomposed of glacial till but are generally confinedto the highlands north, west, and south of Boston.These mapped areas of ground moraine also includeextensive areas of bedrock exposure in some of thehigher elevations; however, since the areas of bedrockare often discontinuous and occur almost exclusivelywithin the ground moraine unit, we do not break outindividual areas of bedrock exposure on the maps.Rather, we note that the ground moraine unit canvary in thickness from several tens of meters to zero,and bedrock exposures can occur in zones of zeroground moraine thickness. Where present, the groundmoraine till ranges in thickness from zero up toapproximately 40 meters, while drumlin till can reachover 50 meters in thickness (Chute, 1966; Woodhouseet al., 1991).

The till is generally composed of poorly sortedsand, gravel, and cobbles in a clay matrix, and it isgenerally well consolidated and very dense. Largecobbles and boulders up to 1 m in diameter occurrarely throughout the till, but are often confined to

Table 1. Hazard criteria used in this study and regional susceptibility mapping criteria based on geologic characteristics of various map units(after Youd and Perkins, 1978).

Hazard Category Geologic Criteria (Susceptibility) Geologic UnitsGeotechnical

Boring-Based Criteria

High hazard Modern to Holocene; saturated; abundantcohesionless, uncompacted sediments

Artificial fill .20 percent of borings withliquefiable samplesActive beach deposits

Moderate hazard Holocene to Pleistocene; saturated; variableamounts of cohesionless, uncompactedsediments

Glaciofluvial deposits 5 to 20 percent of borings withliquefiable samplesMarsh deposits

Low hazard Pleistocene to pre-Pleistocene; non-saturatedto saturated; well indurated; cohesive;limited cohesionless sediments

Glacial till (drumlin andground moraine)

,5 percent of borings withliquefiable samples

Bedrock

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Figure 2. Quaternary geologic map of the Boston metropolitan area, as compiled from published maps and field reconnaissance (see textfor references).



the upper 3–4 m (Woodhouse et al., 1991). Siltylaminations and well-developed internal structure areoften present, in some places highly disrupted andfolded by the motion of the glacial ice (Kaye, 1961;Woodhouse et al., 1991). The till ranges in color frombrown to yellow to gray. The till was present in 22borings in the database. SPT blow counts in the tillwere variable but generally ranged from about 20 torefusal. As a result of their geologic characteristics,both the drumlin till and the ground moraine till arenot expected to be susceptible to liquefaction.

The glaciofluvial deposits encompass a variety ofdeposits formed by the transport of glacially derivedmaterials, either from the glacier front or by sub-glacial flow, including outwash, eskers, kettles, kamefields, and terraces. These deposits are groupedtogether for mapping purposes, and they are referredto as glaciofluvial deposits. These are composedprimarily of stratified sands and gravels that areheterogeneous in three dimensions as well as in bothdensity and consolidation. The glaciofluvial deposits,with thicknesses of meters to tens of meters, oftenoverlie ground moraine till, and in several locations(e.g., Mystic Lakes–Fresh Pond area), they fill buriedbedrock valleys up to about 70 m deep (Chute, 1959).The outwash units range in color from tan to brownand yellow, and they tend to be loose to dense. Theglaciofluvial units were encountered in 78 borings,and reported SPT blow counts ranged from five torefusal. The presence of large zones of sand and sandysilt in this unit, as well as zones with relatively lowblow counts, indicates that the glaciofluvial units maybe susceptible to liquefaction.

Modern marsh deposits are common in the studyarea and occur both as salt marshes and estuaries alongthe coastal areas and as freshwater marshes alongstreams and rivers further inland. Marsh deposits aregenerally composed of fine sands, silts, and clays, withabundant peat layers. Thicknesses can reach severalmeters. These units are generally loose, with SPT blowcounts generally below 10. Marsh sediments wereencountered in 81 samples from 18 borings. Urbani-zation and suburban sprawl have resulted in a largeamount of filling of these regions over the last 75 years;therefore, artificial fill often overlies loose marshdeposits. We consider the marsh deposits to bemoderately susceptible to liquefaction based on thepresence of discrete layers of saturated, cohesionlesssediments between the more organic strata.

Beach deposits represent the sediments depositedby ongoing modern and historic coastal processes. Ingeneral, these are composed of sand and gravel andhave thicknesses ranging up to several meters. Ina small number of borings, extremely high blowcounts within the beach deposits indicated the

presence of either buried boulders or fill that wassubsequently buried by placement of sand duringbeach reclamation or stabilization. Geologically, thedeposition of beach deposits results in loose and oftensaturated sands; therefore, we argue that beach sandsshould be mapped as highly liquefiable deposits.

We also recognized several stratigraphic units thatoccur in the subsurface but do not crop out on thesurface and thus could not be included in the geologicmaps. These units can be laterally extensive; however,they generally require relatively dense subsurfaceboring data to map accurately. An example of oneof these units is the famous Boston Blue Clay, whichunderlies much of the Massachusetts Bay area andhas been extensively studied in the past because of itsimpact on deep foundations of buildings in thedowntown area. The Blue Clay is a well-beddeddeposit of clay, silt, and fine sand formed from therock flour component of glacial outwash (Wood-house et al., 1991), and it is not considered to be atrisk of liquefaction.

Artificial Fill

The original settlement of Boston was situated onand adjacent to Beacon Hill, a drumlin which formedan island at high-tide (Woodhouse, 1989; Seasholes,2003). Due to subsequent urbanization, primarilyduring the mid 1800s to early 1900s, non-engineeredartificial fill was placed on the adjacent low-lying tidalmarshes, estuaries, and floodplains adjacent to theBoston Harbor and the Charles River (Figure 3). Thefill history of Boston has recently been documentedusing historical maps and documents (Ty, 1987;Seasholes, 2003). Each episode of land reclamationused specific source material and a different fillingmethod; therefore, it is useful to break up the fill unitinto subunits, which can then be characterized in-dividually. Figure 4 presents the 10 fill units delineatedin this study: Charlestown, Cambridge, Back Bay,West Cove, Mill Pond, East Cove, South Cove, SouthBay, South Boston, and East Boston. Although tidalmarsh, estuary, and till deposits directly underlie them,these regions are mapped as artificial fill.

In general, the fill layer consists of loose to verydense sand, gravelly sand, or sandy gravel intermixedwith varying amounts of silt, clay, cobbles, boulders,and miscellaneous materials such as brick, ash, rubble,trash, or other foreign materials (Ty, 1987; Wood-house et al., 1991). The source materials include bothgranular and cohesive material that was obtained fromnearby quarries and dumped loosely at sites, generallywithout sorting or compaction. As a result, propertiesof the fill layer are extremely variable, and blow countsrange up to refusal. In addition, much of the fill is

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saturated as a result of a relatively shallow (althoughhighly variable) groundwater table.

The regions mapped as artificial fill are consideredto have the highest liquefaction potential in the Bostonarea (especially surrounding downtown Boston). If it issaturated and cohesionless, historic (non-engineered)fill is generally considered susceptible to liquefactionbecause it was loosely placed. Most of the fillunderlying newer buildings in Boston is engineered fillrather than the loosely placed historic fill discussedhere. Engineered fill, when properly placed andcompacted, is usually dense and not susceptible toliquefaction under the modest seismic loading expectedin Boston. The historic fill likely remains beneathmany historic buildings and roadways.

SUBSURFACE CHARACTERIZATION

Liquefaction Susceptibility

The surficial geology maps (Figures 2 and 3) showthe six geologic units: artificial fill, marsh deposits,glaciofluvial deposits, drumlin till, ground morainetill, and beach deposits. Geotechnical data were

collected in each of these units; however, the artificialfill unit near downtown Boston and Cambridge wasthe only geologic unit that was densely sampled. Thegeotechnical data were only sparsely available overthe remainder of the study region. Although we usedgeotechnical data in all of the geologic units toevaluate liquefaction potential, the susceptibilitymapping of all units other than the artificial fill reliedmore heavily on the geologic characterization, asdescribed next. For the artificial fill unit, a statisticalclassification was also applied.

In order to use the geotechnical data to ascertainliquefaction susceptibility, all samples in each of the sixsurficial geology categories were queried from thedatabase. Samples from all units in the boring wereincluded in the analyses. The resulting collections ofsamples included all soil samples taken within thegeographic confines of that surficial geologic unit.Susceptibility analyses were run for these samplesusing the methodology described previously, anda PGAtrigger of 0.12g was used as the threshold groundmotion for determining failure of each sample. Thedata and results for each geologic unit are summarizedin Table 2, and the distributions of susceptibility

Figure 3. Quaternary geologic map of the Boston downtown area.



categories for the three geologic units with susceptiblematerial are shown in Figure 5. As expected, theartificial fill is the most susceptible unit. Marshdeposits also exhibit a relatively high level of suscep-tibility. The distribution of liquefiable samples in theglaciofluvial deposits exhibits moderate susceptibility.

Very few samples were taken in the drumlin deposit(only 13 samples from six borings across the studyarea). Based on the depositional conditions of theglacial till that makes up the drumlins, as well as fromfield observations of exposures of the till, the materialis expected to be very dense and not susceptible toliquefaction. Samples from the drumlin depositconfirm this expectation (zero percent liquefiable).Therefore, all drumlin till deposits were categorized aslow susceptibility. Similarly, very few samples were

taken in the ground moraine till (45 samples from 17borings). The ground moraine till is generally a thinglacial till deposit over bedrock. These deposits areexpected to be dense to very dense. The samples in theground moraine deposit confirmed the expectation ofdense soils; therefore, ground moraines till wasmapped as low hazard.

Based on depositional environment and fieldevidence, the glaciofluvial deposits are composedprimarily of interbedded sand and gravel layers withsome silt and cobble interbeds of variable density.The results from the geotechnical data are variable: 9out of 79 borings, or 12 percent, have liquefiablematerial given the design earthquake. Some boringscontain only non-liquefiable samples, while othershave several samples that would liquefy for a larger

Figure 4. Geographic subunits of artificial fill in the central Boston area.

Table 2. Distribution of all analyzed samples by geologic unit characterized as susceptible to liquefaction, given a peak ground accelerationof 0.12g.

Number ofSamples

Numberof Borings

Percent of Samples Susceptible to theDesign Earthquake (PGA 5 0.12g)

Percent of Borings with at Least One SampleSusceptible to the Design Earthquake

Artificial fill 9,898 1,727 7.6 29Marsh deposits 81 18 7.4 22Beach deposits*** 29 8 0 0Glaciofluvial deposits 347 79 3.2 12Drumlin*** 13 6 0 0Ground moraine*** 45 17 0 0

***Indicates small sample.

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earthquake than the design earthquake (PGA .

0.12g). The glaciofluvial deposits were mapped asmoderate hazard; however, if the design earthquakewas altered, the susceptibility could possibly increase.The liquefiable samples within the glaciofluvial unitsare isolated, and, therefore, we do not expect large,continuous zones of liquefiable materials.

The marsh deposits vary from silty to sandy soils,with abundant organic layers. Most of the soils in themarsh deposits are loose and saturated. The silty andorganic-rich soils are not generally liquefiable; how-ever, the sandy soils in these deposits tend to beliquefiable in the design earthquake. In the marshdeposits, 22 percent of the borings contain samplesthat are susceptible to liquefaction in the designearthquake (Table 2). This is similar to the suscepti-bility of the artificial fill (see following). The marshdeposits were therefore mapped as high hazard.

The few samples in the beach deposit were notrepresentative of the sandy soils expected in a Holo-cene beach deposit. After close examination of the 29samples in the beach deposit, none of the samples was

taken in an actual beach deposit. Most were takenwithin historic artificial fill placed along the seashore,which has been subsequently overlain by beach sand,either placed during beach restoration or depositednaturally, and borings have encountered miscella-neous dense materials. Based on geologic criteria,natural Holocene beach deposits are expected to beloose, saturated sandy deposits and are highlysusceptible to liquefaction. The beach deposits weretherefore mapped as high hazard.

Overall, 29 percent of borings in the artificial fillcontained at least one liquefiable sample. When wesubdivided the fill into the individual subregions assummarized in Table 3, the susceptibility was spatial-ly variable depending on the fill and constructionhistory of the area. In several of the fill regions, therewere large continuous zones of liquefiable materials(especially West Cove, Mill Pond, Cambridge, Charles-town, and Back Bay). A detail of Back Bay, with theliquefaction categories from the geotechnical borings, isshown in Figure 6. On the other hand, South Boston,South Cove, South Bay, East Cove, and East Boston

Figure 5. Histograms showing distribution of susceptible (L) and non-susceptible (NL) samples in liquefaction susceptibility categories forthe three mapped geologic units with susceptible samples, for M 5 6.0 and PGAtrigger 5 0.12g.

Table 3. Distribution of all analyzed samples for geographically designated artificial fill subunits in central Boston, and percent of samplescharacterized as susceptible to liquefaction, given a peak ground acceleration of 0.12g.

GeographicSubunit

Number ofSamples

Number ofBorings

Number ofLiquefiable

Samples

Percent of SamplesSusceptible to the Design

Earthquake (PGA 5 0.12g)

Percent of Borings with at LeastOne Sample Susceptible to the

Design Earthquake

Back Bay 152 44 25 16 41West Cove 104 18 14 13 61Mill Pond 719 116 84 12 46East Cove 57 13 3 5 15South Cove 364 121 32 9 18South Bay 374 130 20 5 14South Boston 935 220 56 6 21East Boston 1,453 315 49 3 14Charlestown 521 110 48 9 35Cambridge 4,280 638 423 10 40



demonstrated a more moderate level of susceptibility,though still higher than any other geologic unit inBoston.

Figure 7 shows the liquefaction susceptibility mapfor the greater Boston area, while Figure 8 shows thedistribution of liquefiable samples in the artificial fillaround the Boston peninsula. The Cambridge fillregion is highly susceptible to liquefaction for thedesign earthquake. It should be noted that someregions of fill, particularly those underlying modernhighways and developments, have most likely beeneither removed or adequately compacted duringconstruction and designed to be resistant to liquefac-tion. However, because we lacked quantitative geo-technical data from most of these site-specific projectareas, we mapped them like the other non-engineeredfill. Thus, all of the artificial fill regions were mappedas high hazard.

DISCUSSION

In greater Boston, the liquefaction susceptibility ofnear-surface deposits, both natural and artificial,varies widely across the region. The artificial fillunits, marsh deposits, and the beach deposits aremapped as high hazard for liquefaction. The beachdeposit characterization is based solely on thesurficial geology, since the geotechnical data takenin the beach deposits were sparse and not represen-tative. The artificial fill unit in downtown Boston andin Cambridge has been densely sampled, and 29

percent of borings within the artificial fill containsome susceptible soils. The liquefaction susceptibilityis spatially variable across the artificial fill unit andincludes many continuous zones of liquefiable mate-rial. The marsh deposits and glaciofluvial depositshave 22 percent and 12 percent of borings with somesusceptible material, respectively. The glaciofluvialsediments were therefore mapped as moderate sus-ceptibility, while the marsh sediments were mapped ashigh susceptibility.

The regional liquefaction susceptibility map forBoston and surrounding communities (Figure 7)shows that the highly susceptible regions are concen-trated around downtown Boston, where most of thehistoric artificial fill and underlying marsh depositsare located. Although the artificial fill is mapped ashigh hazard, the material is highly heterogeneous andvaries from very loose to very dense. Completeliquefaction of the entire fill region is not likely tooccur; however, large contiguous zones (possiblyunderlying entire city blocks) are expected. Baise etal. (2006) presented a detailed case study of thesusceptibility of the artificial fill along the Cambridgewaterfront area, which demonstrated the spatialvariability of susceptibility in the fill. While thisemphasizes the potential hazard of coseismic lique-faction to structures built in regions of artificial fill, itis important to note that the downtown Boston areahas been extensively developed, and it is conventionalfor large projects to remove the historic fill beforeconstruction, or to utilize deep foundations seated in

Figure 6. Detail of Boston’s Back Bay area showing results of liquefaction susceptibility analyses within the artificial fill. Shaded portionsof pie charts represent proportion of different susceptibilities of samples from each boring, for M 5 6.0 and PGAtrigger 5 0.12g.

Brankman and Baise


Figure 7. Map showing liquefaction susceptibility of Quaternary geologic units and artificial fill in the Boston region.



stable material beneath the fill. Therefore, the hazardto large modern structures is most likely minimal.However, smaller older structures, as well as surfaceand near-surface roadways and utilities (lifelines) arestill likely at risk.

The glaciofluvial sediments were relatively under-sampled with respect to the large surface area thatthey cover. Based on the boring data, this unit is onlyslightly to moderately susceptible; 9 of 79 boringshave at least one sample that is susceptible in thedesign earthquake. Where observed in several in situexposures throughout the study area, however, thesandy portions of the outwash appear to be loose andunconsolidated, and they often comprise laterallyextensive and connected deposits. Given these ob-servations, and assuming that similar conditions existin the subsurface, it is possible that the boring data donot adequately characterize the susceptibility of thisunit, and that significant portions of the glaciofluvialdeposits could be at risk for liquefaction. According-ly, we assigned the unit a susceptibility rating ofmoderate. Additional boring data from throughoutthis unit would help to better constrain the potentialresponse of this unit during coseismic groundmotions.

Groundwater level has a primary control on theliquefaction susceptibility of a given sediment unit. In

our analyses, we conservatively assumed a groundwa-ter level equivalent to the highest reported level orsurface groundwater table if none was reported.Seasonal variations in rainfall and snow meltwatercan be expected to change groundwater levels; asa result, susceptibility of given samples from theboring database may increase or decrease.

As mentioned already, the susceptibility criteriapresented here do not predict expected or possibletypes of deformation resulting from liquefaction, suchas lateral spreading or settlements. These largelydepend on the thickness of the susceptible unit, depthto susceptible unit, lateral extent of susceptible unit,surface and intra-unit topography, and nearbystructures, and as such, they are local, site-specificeffects that must be considered individually. Thesusceptibility maps produced in this study are meantfor the regional scale and not the site-specific scale.This information can and should be augmented withdetailed site explorations to confirm the liquefactionhazard at a specific site.

A primary shortcoming of this mapping projectwas the lack of data in large regions of the study area,particularly in outlying areas. For this study, the mostsusceptible unit is the artificial fill; therefore, onlya limited effort was made to collect geotechnical dataover greater Boston. The maps are therefore pre-

Figure 8. Detail map showing varying liquefaction susceptibility of fill units in downtown Boston.

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dominantly based on surficial geology, although theunderlying classifications are supported by thequantitative geotechnical data.

CONCLUSIONS

We applied the regional liquefaction mappingcriteria presented in Table 1 to prepare liquefactionhazard maps for greater Boston. The mapping criteriaconsist of three hazard classes (low, moderate, andhigh) that refer to varying expected extents ofliquefaction. The criteria are based on surficialgeology and geotechnical data. The intention of themapping criteria was to provide a hazard class thataccounted for the variability of geologic materials andthe distribution of liquefiable materials within a re-gional geologic unit.

We assembled surficial geologic maps for thegreater Boston area (Figures 2 and 3). The mapswere developed from existing high-quality, large-scale, published maps, smaller-scale maps of theentire study area, as well as field reconnaissancemapping using field exposures and geomorphologicalinterpretation. To complement the surficial geologicmaps, we assembled an electronic database of geo-technical data from 2,963 test borings. The geo-technical data included stratigraphy, soil sampledescription, soil type, groundwater level, and SPTblow count. Although the data are concentrated inthe downtown area, the distribution covers the entirestudy region. The SPT blow count data were analyzedfor susceptibility to liquefaction according to stan-dard geotechnical procedures (Youd et al., 2001).

Using the mapping criteria, the surficial geologymaps, and the geotechnical data, we preparedliquefaction hazard maps for the greater Boston area.These maps are appropriate for the design earthquakefor Boston, MA (M6.0 and PGA 5 0.12g). Artificialfill, marsh deposits, and beach deposits are mapped ashigh hazard. Marsh deposits are loose deposits of siltsand sands. The silty organic soils are not liquefiable,and the sandy soils tend to be liquefiable during thedesign earthquake. Glaciofluvial deposits are mappedas moderate hazard. Ground moraine and drumlindeposits are mapped as low hazard.

ACKNOWLEDGMENTS

This research was supported by the U.S. GeologicalSurvey (USGS), Department of the Interior, under USGSaward numbers 02HQGR0036 and 02HQGR0040. Theviews and conclusions contained in this document arethose of the authors and should not be interpreted asnecessarily representing the official policies, either

expressed or implied, of the U.S. government. Wethank Rebecca Higgins and Kevin Dawson (TuftsUniversity) for their assistance in subsurface datacollection, and Christopher Hitchcock (W.L.A.) fortechnical assistance and review. We also thank RalphLoyd and two anonymous reviewers for extremelythorough and constructive reviews and comments,which greatly improved the manuscript. The sub-surface data collected over the course of theseinvestigations are available to interested individuals;please contact Laurie Baise ([email protected])for an electronic copy of the database.

REFERENCES

BAISE, L. G.; HIGGINS, R. B.; AND BRANKMAN, C. M., 2006,Liquefaction hazard mapping—Statistical and spatial char-acterization of susceptible units: Journal Geotechnical Geoen-

vironmental Engineering, Vol. 132, No. 2, pp. 705–715.

BAROSH, P. J.; KAYE, C. A.; AND WOODHOUSE, D., 1989, Geology ofthe Boston basin & vicinity: Civil Engineering Practice,Vol. 4, No. 1, pp. 39–52.

BOSTON SOCIETY OF CIVIL ENGINEERS, 1969, Boring data fromgreater Boston: Journal Boston Society of Civil Engineers,Vol. 56, No. 3–4, pp. 131–293.

CALIFORNIA GEOLOGICAL SURVEY, 2007, Seismic Hazards Zonation

Program,available at http://www.conservation.ca.gov/cgs/shzp/

CHUTE, N. E., 1959, Glacial Geology of the Mystic Lakes–Fresh

Pond Area, Massachusetts: U.S. Geological Survey Bulletin1061-F, pp. 187–216.

CHUTE, N. E., 1965, Surficial Geologic Map of the Blue Hills

Quadrangle, Norfolk, Suffolk, and Plymouth Counties, Mas-

sachusetts: U.S. Geological Survey Map GQ-463.

CHUTE, N. E., 1966, Geology of the Norwood Quadrangle, Norfolk

and Suffolk Counties, Massachusetts: U.S. Geological SurveyBulletin 1163, pp. B1–B78.

CROSBY, I. B., 1923, The earthquake risk in Boston: Journal Boston

Society of Civil Engineers, Vol. 10, No. 10, pp. 421–430.

EBEL, J. E., 1996, The seventeenth century seismicity ofnortheastern North America: Seismological Research Letters,Vol. 67, No. 3, pp. 51–68.

EBEL, J. E., 1999, Speculations on the source parameters of the1638 earthquake in the northeastern United States usinginferences from modern seismicity: Seismological Research

Letters, Vol. 70, No. 1, p. 114.

EBEL, J. E., 2000, A reanalysis of the 1727 earthquake at Newbury,Massachusetts: Seismological Research Letters, Vol. 71,No. 3, pp. 364–374.

EBEL, J. E., 2006, The Cape Ann, Massachusetts, earthquake of1755: A 250th anniversary perspective: Seismological Research

Letters, Vol. 77, No. 1, pp. 74–86.

HITCHCOCK, C. S. AND HELLEY, E. J., 2000, First Year Annual

Report: Characterization of Subsurface Sediments for Lique-

faction Hazard Assessment—Southern San Francisco Bay

Area: National Earthquake Hazards Reduction Program,U.S. Geological Survey Award Number 99-HQ-GR-0097.

HITCHCOCK, C. S.; LOYD, R. C.; AND HAYDON, W. D., 1999,Mapping liquefaction hazards in Simi Valley, Venturacounty, California: Environmental Engineering Geoscience,Vol. 5, No. 4, pp. 441–458.

JUANG, C. H.; JIANG, T.; AND ANDRUS, R. D., 2002, Assessingprobability-based methods for liquefaction potential evalua-



tion: Journal Geotechnical Geoenvironmental Engineering,Vol. 128, No. 7, pp. 580–589.

KAYE, C. A., 1961, Pleistocene Stratigraphy of Boston, Massachu-setts: U.S. Geological Survey Professional Paper 424-B,pp. B-73–B-76.

KAYE, C. A., 1978, Surficial Geologic Map of the Boston Area,Massachusetts: U.S. Geological Survey Open-File Report 78-111.

KAYE, C. A., 1982, Bedrock and Quaternary geology of the Bostonarea, Massachusetts: Geological Society of America Reviewsin Engineering Geology, Vol. 5, pp. 25–40.

MONAHAN, P. A.; LEVSON, V. M.; MCQUARRIE, E. J.; BEAN, S. M.;HENDERSON, P.; AND SY, A., 1998, Seismic microzonationmapping in Greater Victoria, British Columbia, Canada. InDakoulas, P. and Yegian, M. (Editors), GeotechnicalEarthquake Engineering and Soil Dynamics III: GeotechnicalSpecial Publication 75, American Society of Civil Engineers,Seattle, WA, pp. 128–140.

MONAHAN, P. A.; LEVSON, V. M.; HENDERSON, P.; AND SY, A., 2000,Relative Liquefaction Hazard Map of Greater Victoria, BritishColumbia: Geoscience Map 2000-3a, British Columbia, Min-istry of Energy and Mines, Geologic Survey Branch, avail-able at http://www.em.gov.bc.ca/DL/Hazards/liquefaction.pdf

OLDALE, R. N., 1962, Surficial Geology of the Reading Quadrangle,Massachusetts: U.S. Geological Survey Map GQ-168.

PLANT, M., 1742, A journal of the shocks of earthquakes felt nearNewbury in New-England, from the year 1727 to the year1741. Communicated in a letter from the Reverend Mr.Matthias Plant to the Reverend Dr. Bearcroft: PhilosophicalTransactions of the Royal Society of London (1663–1775),Vol. 42 (1742–1743), pp. 33–42.

SEASHOLES, N., 2003, Gaining Ground: MIT Press, Cambridge, MA.SEED, H. B. AND IDRISS, I. M., 1971, Simplified procedure for

evaluating soil liquefaction potential: ASCE Journal of SoilMechanics, Vol. 97(SM9), pp. 1249–1273.

THOMPSON, W. B.; CHAPMAN, W. F.; BLACK, R. F.; RICHMOND, G.M.; GRANT, D. R.; AND FULLERTON, D. S., 1991, Quaternarygeologic map of the Boston 4 3 6 quadrangle, United Statesand Canada. In Quaternary Geologic Atlas of the UnitedStates: U.S. Geological Survey Map I-1420 (NK-19).

THORSON, R. M., 2001, Remote aquifer response to the 18November 1755 Cape Anne earthquake: Seismological Re-search Letters, Vol. 72, No. 3, pp. 401–403.

TUTTLE, M. AND SEEBER, L., 1991, Historic and prehistoric

earthquake-induced liquefaction in Newbury, Massachusetts:

Geology (Boulder), Vol. 19, No. 6, pp. 594–597.

TUTTLE, M.; SIMS, J. D.; AND ROY, D., 2000, Paleoseismology

Investigations in the Greater Boston, Massachusetts, Area:

Final Report for U.S. Geological Survey Award No. 1434-

HQ-98-GR-00001.

TY, R. K. S., 1987, History and Characteristics of Man-Made Fill

in Boston and Cambridge: Unpublished M.S. Thesis, De-

partment of Civil Engineering, Massachusetts Institute of

Technology, Cambridge, MA.

U.S. GEOLOGICAL SURVEY (USGS), 2007, Conterminous States

Probabilistic Maps and Data: Electronic document, available

at http://earthquake.usgs.gov/research/hazmaps/products_data/

48_States/index.php

WHITMAN, R. V., 2002, Ground motions during the 1755 Cape

Ann earthquake. In Earthquake Engineering Research In-

stitute: Proceedings of the Seventh U.S. National Conference

on Earthquake Engineering. Oakland, CA.

WOODHOUSE, D., 1989, The history of Boston: The impact of

geology: Civil Engineering Practice, Vol. 4, No. 1, pp. 33–38.

WOODHOUSE, D.; BAROSH, P. J.; JOHNSON, E. G.; KAYE, C. A.;

RUSSELL, H. A.; PITT, W. E., JR.; ALSUP, S. A.; AND FRANZ, K.

E., 1991, Geology of Boston, Massachusetts, United States of

America: Bulletin Association of Engineering Geologists,

Vol. 28, No. 4, pp. 375–512.

YOUD, T. L. AND PERKINS, D. M., 1978, Mapping liquefaction-

induced ground failure potential: Journal Soil Mechanics

Foundations Division, Vol. 104, No. 4, pp. 433–446.

YOUD, T. L. AND PERKINS, D. M., 1987, Mapping of liquefaction

severity index: Journal Geotechnical Engineering, Vol. 113,

No. 11, pp. 1374–1392.

YOUD, T. L.; IDRISS, I. M.; ANDRUS, R. D.; ARANGO, I.; CASTRO,

G.; CHRISTIAN, J. T.; DOBRY, R.; FINN, W. D. L.; HARDER, L.

F., JR.; HYNES, M. E.; ISHIHARA, K.; KOESTER, J. P.; LIAO, S.

S. C.; MARCUSON, W. F., III; MARTIN, G. R.; MITCHELL, J. K.;

MORIWAKI, Y.; POWER, M. S.; ROBERTSON, P. K.; SEED, R. B.;

AND STOKOE, K. H. I. I., 2001, Liquefaction resistance of soils:

Summary report from the 1996 NCEER and 1998 NCEER/

NSF Workshops on Evaluation of Liquefaction Resistance

of Soils: Journal Geotechnical Geoenvironmental Engineering,

Vol. 127, No. 10, pp. 817–833.

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Liquefaction Susceptibility Mapping in Boston, Massachusetts

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