Name: Tongass Landslide Initiation

Display Field: LANDSLIDE_NAME

Type: Feature Layer

Geometry Type: esriGeometryPoint

Description: This feature class is a polygon landslide inventory of the Tongass National Forest. The digital version of this inventory was started in the year 2000 and the once-over inventory was completed in 2017. The feature class is updated annually or as new imagery becomes available. Both field and photo interpreted landslides are included. The inventory includes all mass wasting features--including talus slopes, snow avalanche fields, and snow avalanche chutes. Therefore, it may be necessary to exclude some mass wasting features prior to analysis depending on the intended use of the data. Each of these are coded differently in the attributes. Most of the landslide polygons were digitized on the 1998 to 2010 ortho photos in GIS, although some were digitized using imagery taken more recently. All the landslides have been age bracketed within the available photo data sets to estimate date of occurrence. Many of them were age bracketed using air photos back to the 1929 Navy Trimegon photos. All landslides have been dated before or after 1948 imagery and before or after the 1996 to 1998 imagery. There is an associated point feature class that contains the landslide initiation zone approximations. These points only exist for true landslides--debris avalanches, debris torrents, combination debris avalanches/torrents, slumps, rotational failures, and rock fall-initiated failures. The 2023 update included new slides from 2020 imagery on Chichagof Island. The 2024 update included new slides from 2023 imagery of Admiralty, Kupreanof, Mitkof, and Wrangell Islands as well as part of Kuiu Island. The 2025 update included additional slides on Mitkof, Wrangell, Etolin and Revilla Islands and adjacent mainland. The 2025 update also revised fields and some previous entries to record imagery sources and more precise dates of occurrence.

Copyright Text: SM.FS.data@usda.gov

Default Visibility: true

MaxRecordCount: 2000

MaxSelectionCount: 2000

Supported Query Formats: JSON, geoJSON, PBF

Min Scale: 0.0

Max Scale: 0.0

Supports Advanced Queries: true

Supports Statistics: true

Has Labels: false

Can Modify Layer: true

Can Scale Symbols: false

Use Standardized Queries: true

Supports Datum Transformation: true

Extent:

XMin: -139.6480368709063
YMin: 54.565019549970934
XMax: -129.5164538486691
YMax: 60.11645169946484
Spatial Reference: 4269  (4269)  LatestVCSWkid(0)

Drawing Info:

Renderer:
Simple Renderer:
Symbol:
Label: N/A
Description: N/A
Transparency: 0
Labeling Info:

Feature Draw Order:

N/A

Advanced Query Capabilities:

Supports Statistics: true
Supports OrderBy: true
Supports Distinct: true
Supports Pagination: true
Supports TrueCurve: true
Supports Returning Query Extent: true
Supports Query With Distance: true
Supports Sql Expression: true
Supports Query With ResultType: false
Supports Returning Geometry Centroid: false
Supports Binning LOD: false
Supports Query With LOD Spatial Reference: false
Supports Percentile Statistics: true
Supports Having Clause: true
Supports Count Distinct: true
Supports Time Relation: true
Supports Sql Format: false
Supports Query Analytic: true
Supports Query With Current User: true

HasZ: false

HasM: false

Has Attachments: false

HTML Popup Type: esriServerHTMLPopupTypeAsHTMLText

Type ID Field: null

Fields:

• objectid ( type: esriFieldTypeOID, alias: OBJECTID )
• tnf_ls_no ( type: esriFieldTypeSmallInteger, alias: TNF_LS_NO )
• inventory ( type: esriFieldTypeString, alias: INVENTORY, length: 4 )
• latest_date_not_seen ( type: esriFieldTypeDate, alias: LATEST_DATE_NOT_SEEN, length: 8 )
• not_seen_source ( type: esriFieldTypeString, alias: NOT_SEEN_SOURCE, length: 255 )
• first_date_seen ( type: esriFieldTypeDate, alias: FIRST_DATE_SEEN, length: 8 )
• seen_source ( type: esriFieldTypeString, alias: SEEN_SOURCE, length: 255 )
• confid_dat ( type: esriFieldTypeString, alias: CONFID_DAT, length: 9 )
• estim_year ( type: esriFieldTypeInteger, alias: ESTIM_YEAR )
• treatment ( type: esriFieldTypeString, alias: TREATMENT, length: 1 )
• rd_initiated ( type: esriFieldTypeString, alias: RD_INITIATED, length: 1 )
• fail_type ( type: esriFieldTypeString, alias: FAIL_TYPE, length: 14 )
• examiner ( type: esriFieldTypeString, alias: EXAMINER, length: 50 )
• slope_per ( type: esriFieldTypeSmallInteger, alias: SLOPE_PER )
• slope_sha ( type: esriFieldTypeString, alias: SLOPE_SHA, length: 2 )
• bdrk_f_zon ( type: esriFieldTypeString, alias: BDRK_F_ZON, length: 3 )
• pm_f_zone ( type: esriFieldTypeString, alias: PM_F_ZONE, length: 3 )
• landslide_name ( type: esriFieldTypeString, alias: LANDSLIDE_NAME, length: 50 )
• landwehr_n ( type: esriFieldTypeString, alias: LANDWEHR_N, length: 3 )
• grouped_sl ( type: esriFieldTypeString, alias: GROUPED_SL, length: 2 )
• recurrence ( type: esriFieldTypeString, alias: RECURRENCE, length: 9 )
• acres ( type: esriFieldTypeDouble, alias: ACRES )
• globalid ( type: esriFieldTypeGlobalID, alias: globalid, length: 38 )
• shape ( type: esriFieldTypeGeometry, alias: SHAPE )

Supported Operations:   Query   Query Attachments   Query Analytic   Generate Renderer   Return Updates

  Iteminfo   Thumbnail   Metadata