Cascadia tsunami deposit database

Online link https://geo-nsdi.er.usgs.gov/metadata/open-file/03-13/metadata.faq.html
Description The Cascadia Tsunami Deposit Database contains data on the location and sedimentological properties of tsunami deposits found along the Cascadia margin. Data have been compiled from 52 studies, documenting 59 sites from northern California to Vancouver Is
Originators Peters, Robert; Jaffe, Bruce; Gelfenbaum, Guy; and Peterson, Curt
Publication U.S. Geological Survey Open-File Report 03-13

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ctd_database.txt (table row)

Description of a tsunami deposit

Label Definition
location The name of the location where the tsunami deposits are located, including state. The name may refer to the nearest easily recognized place name, such as a town, a body of water, or other geographic feature.
catalog # The catalogue number is an arbitrary number associated with each row entry. It may be used to refer to the entry or access the entry at a later date.
site # The site number is assigned in an ascending order based on latitude. The northernmost site in the database is assigned the number 1 and site number increases as the latitude of the site decreases. The site number of the southernmost site gives the total number of sites in the database.
core/section/secondary location Where individual cores at a site are listed separately, the core number is given here. If no core number is given in the publication, a number is assigned. If the author divides a site into sections or secondary locations, their designations are given here. If no designation is given, one is assigned.
latitude Latitudes reported by the authors are used when possible, otherwise they are measured from large-scale maps. Latitude and longitude are reported in decimal degrees.
longitude Longitudes reported by the authors are used when possible, otherwise they are measured from large-scale maps. Latitude and longitude are reported in decimal degrees.
depositional setting Depositional setting for tsunami sedimentation, such as lake, coastal marsh, freshwater marsh, etc.
inundation distance, physiographic setting, and inundation reference Inundation distance for open coastal settings is the maximum distance inland, normal to the shoreline, inundated by the tsunami. However, in other physiographic settings, the term inundation distance is subject to interpretation and the definition may change depending on the focus of the study. In a large bay or estuary, which may extend several kilometers inland from the open coast, a tsunami may propagate up a bay or even be focused by the bay. A tsunami that has a relatively small inundation distance in an open coastal setting or along a cliffed coast may travel several kilometers up a river or estuary. An inundation distance of 3 km when the site is located on a marshy riverbank does not suggest that the tsunami would inundate 3 km inland on the open coast. Therefore, when considering inundation distance, it is important to note the physiographic setting and the reference point from which inundation distance is measured. When known, the reference point for measuring the inundation distance is given (inundation reference)."Open coast" means the inundation distance is measured normal to the trend of the shoreline. This usually applies to lakes and back- barrier marshes in open coastal settings. When warranted, a more specific reference may be given. "River mouth" means the distance is measured from the mouth of the river or estuary, perpendicular to the trend of the coast at the river mouth. "Up river" means the distance up a river or estuary and will not necessarily be in a strait line but will follow the coarse of the river. Bayshore means perpendicular to the trend of the shore within a bay. When "bayshore" is added to river descriptions it means the distance is measured from the mouth of a river that flows into a bay. Fjords are treated like open coastal settings unless specifically referred to as a river or estuary. When a more specific term is required for clarification or if the inundation reference is not clear from the authors description, the authors words may be added or substituted for the above descriptions. For a paleotsunami, the maximum inundation distances reported in the literature usually represent a minimum estimate. The reports are minimum estimates because the full extent of deposits may not be preserved in the geologic record and workable outcrop or coring sites may not extend the full length of the deposit. There is additional uncertainty in determining inundation distances for paleotsunami deposits because the locations of paleoshorelines are rarely known. The study of modern tsunami deposits suggests that actual inundation by a tsunami may extend a short distance beyond the limit of deposition and that deposits may be discontinuous near the limit of inundation.
elevation(mamsl) The present elevation of a site, in meters above present mean sea level. For a paleotsunami site, both the elevation of the site and mean sea level at the time of the tsunami may have been different than at present.
barrier elevation (mamsl) The elevation of a barrier a tsunami must have crossed to leave a deposit at the site, in meters above mean sea level. As with elevation above, we report the modern elevation.
observation/sampling method Method used in collecting data, such as observation from an outcrop or core, and, for cores, the type of coring device used (if specified in the citation).
# cores/sampling localities The number of cores or sampling localities at a site.
# events documented (tsunami + subsidence) The number of subsidence events associated with great earthquakes on the CSZ, whether or not they are associated with tsunamis. Tsunamis not associated with coseismic subsidence are also included. The number of coseismic events present at a site is an important tool to help correlate tsunami deposits.
# tsunami events documented at site the number of tsunami events documented at a site.
subsidence present? (y/n) Are the tsunami deposits associated with coseismic subsidence?
# subsidence events documented at site the number of Subsidence events associated with great earthquakes on the CSZ documented at a site.
# of tsunami deposits associated with subsidence the number of tsunami deposits at a site that are associated with coseismic subsidence.
# of tsunami deposits not associated with subsidence the number of tsunami deposits at a site that are not associated with coseismic subsidence.
event # number assigned to event at a site (tsunami or subsidence), from youngest to oldest. Numbers are site-specific and do not imply correlation with events having the same number at a different site.
tsunami event # number assigned to tsunami deposit at a site, from youngest to oldest.
subsidence event # the number assigned to subsidence event at a site, from youngest to oldest.
amount of subsidence (m) the amount of coseismic subsidence reported.
age (rcybp) Age of deposit in radiocarbon years before present. Ages reported are those of the authors and are usually reported relative to 1950. Ages reported in rcybp need to be calibrated before they can accurately represent the age of the deposit. For some deposits two ages are given. For each age an uncertainty is provided using a plus-or-minus symbol.
age range (cybp) The range of possible ages in calendar years before present. Following the convention of Stuvier and Pearson (1986, 1993), present is taken to be AD1950. Age ranges reported are those of the authors, though for consistency, we have converted ages reported as a date or relative to a date other than 1950 (such as 2000) to years before 1950. Age ranges in calendar years are calibrated using tree ring dendrochronology and take into account errors reported by the lab, errors in the calibration curve, reproducibility, etc..
correlated date If the deposit is correlated by the author to a known or accepted event (such as the 1964 Alaska earthquake and tsunami or the 1700 Cascadia event), the correlated date is given here.
age method/comments Method used to determine the age of the deposits. The age reported represents a maximum age for the deposits. Material dated is usually organic material within the deposit or from the underlying peat layer and may include material that was dead prior to the tsunami or reworked material. Material in growth position or fragile material within the tsunami deposit often provides the most accurate dates. If a series of dates are given from material within or underlying the deposit, the youngest date is reported. Unless noted otherwise, dates reported here use conventional radiocarbon methods (CO2 gas proportional counting, liquid scintillation). Dates calculated using accelerator mass spectrometry (AMS) are noted. Additional notes concerning the age or dating of the deposit is included here.
thickness (cm) The reported thickness of the tsunami deposit, inclusive of all layers present. Thickness is not constant in tsunami deposits. Thinning of the deposit landward and away from channels often characterizes tsunami deposits. Different authors report thickness in different ways. Sometimes thickness is reported as an average thickness or representative thickness, other times only a local thickness is reported. Other times a range of thicknesses is reported.
maximum thickness (cm) If a maximum thickness is reported independent of the average, representative, or range of thicknesses, it is reported here.
geometry description of gradients in thickness (landward thinning, etc.) and continuity of the deposit.
# layers tsunami deposits often have distinct layering in them. Layers may be defined by sand-mud couplets, heavy mineral layers, organic horizons, etc. The number of layers within a tsunami deposit is reported here.
layer thickness (cm) the thickness of individual layers is reported here.
layer characteristics specific characteristics of individual layers, such as defining characteristics, texture, grading, etc. are reported here.
underlying material, overlying material description of the material underlying and overlying the deposit.
lower contact, upper contact description of the contacts bounding the tsunami deposit. Contacts are often characterized as either abrupt (< 0.1 cm), sharp (0.1 cm - 0.5 cm), or gradual (>0.5 cm), but some authors use other terms, such as mantled, erosive, irregular, gradational, etc. More detail is given when provided in the reference.
grain size range The size range of sand grains found in the deposit in units of phi (f), where f = -log2 of the grain diameter (in millimeters) (Krumbein, 1938). This usually is a typical range for the deposit. The presence of clay, silt or gravel may not be reflected in this statistic. The grain size range stated in the database is taken directly from the reference whenever possible. In the literature, grain size range is often given in units other than phi. When grain size range is given in millimeters or using standard terminology from the Udden-Wentworth grain-size scale (Udden, 1914, Wentworth, 1922), grain size range is interpreted using the following conversions: > very coarse sand => 1.000 - 2.000 mm = 0.0 to -1.0 phi > coarse sand => 0.500 - 1.000 mm = 1.0 to 0.0 phi > medium sand => 0.250 - 0.500 mm = 2.0 to 1.0 phi > fine sand => 0.125 - 0.250 mm = 3.0 to 2.0 phi > very fine sand => 0.062 - 0.125 mm = 4.0 to 3.0 phi
grain size distribution The distribution of grain sizes within a deposit
grain size description Prose description of grain size within a deposit. The authors original words are given here whenever possible.
horizontal textural gradient Describes grain size changes in the horizontal direction, such as landward fining or fining away from the channel.
grading grading describes textural changes in the vertical direction within a layer. Normal grading refers to fining upwards. Inverse grading refers to coarsening upwards.
sorting sorting is a measure of the variability of the grain sizes in the deposit and is usually characterized from well sorted (little variability) to poorly sorted (large variability). More quantitative statistical measures have not generally been reported in the Cascadia tsunami deposit literature.
other sedimentary structures or properties miscellaneous sedimentary properties that characterize the deposit or grains within the deposit. The authors original words are given here whenever possible.
composition describes the mineralogical composition of the sediment grains in the deposit. Composition may be reported as specific minerals, percentages or presence of quartz, feldspar, and lithics (QFL), or other more general descriptions provided by the authors. Composition may provide clues to the source of the grains in the deposit.
inclusions material other than sediment grains in a deposit, including plant material, shells or other macrofossils, artifacts, etc.
flow direction gives the direction of flow indicated by the deposit. Flow direction indicators within the deposit may give either general (landward/seaward) or specific directions. Flow direction indicators include sedimentary structures and oriented inclusions such as flopovers (rooted plant material bent over by the tsunami).
microfossils Microfossils, including forams and diatoms, may provide evidence for an ocean or coastal source for sediments in the deposit and therefore are a useful tool for identifying tsunami deposits. Microfossils may also provide evidence for the amount of coseismic subsidence that occurred during a subduction zone earthquake.
chemical evidence describes any chemical evidence that the deposit is from a tsunami.
comments/additional descriptions other information pertaining to the tsunami deposits, site, or publication that does not fit into the other categories is reported here.
reference citing for reference that provided the data by author and year. Complete citing is listed in the reference section of this report and on the references worksheet in the database.
reference type references are categorized by publication venue
reference date date of reference publication
map reference map covering location of site. USGS 7.5 minute quadrangles are used for locations in the United States. National Topographic System (NTS) 1:50,000 maps published by Energy, Mines and Resources, Canada are used for locations in Canada.