Langtang Lirung — Sentinel-1 change and precursor analysis

Original titleSentinel-1 change detection and precursor test, Langtang Lirung, 26 August 2026: derived data, figures and analysis code

Status
Resource eligibility under review
Provider
Sah, Ajay Kumar
Publication date
6 September 2026
Listed assets
10

Resource details

Summary
Backscatter-change raster, figures, script and documentation from an independent radar analysis.
Review findings
The change raster is not a failure-scar polygon. Shadow, layover, snow and arbitrary thresholds affect it. A null amplitude precursor does not rule out slow deformation. Depositor discloses AI assistance; reproduction was not performed. Automated appraisal; no independent human screening or manuscript inclusion assigned. Asset assessment REV-20260908-ASSETS-002 completed 10 newly added or rediscovered asset records; 1 retain explicit follow-up. Titles, technical fields, source versions and interpretation limits are recorded in the asset-review export. Resource eligibility and manuscript inclusion remain separate.
Record type
Event Data Or Code
Provider role
Producer And Or Distributor As Documented
Original language
English
First identified
8 September 2026
Geographic coverage
Source area and/or Bhote Koshi–Trishuli corridor; provider-specific coverage, not a shared surveyed boundary.
Temporal coverage
Event-related observations, analyses and source-specific historical references; dates vary by component.
Collection licence
Under review
Redistribution
Metadata And Links Only; Third Party Bodies Not Published

Inventory

All 10 asset metadata records have been assessed. 1 have flagged follow-up. Read the screening method and findings.

Listed assets
10
Provider-stated total
24192656 bytes summed across source-listed links with known sizes; versions/copies may overlap; unknown sizes excluded
Assets naming another contributor
0
Confirmed reachable without registration
10 of 10
Unavailable endpoints
0

Listed assets

Download CSV
01

Pre-event VV backscatter and matched controls — Langtang Lirung figure

299420 bytes (source-listed)PNG

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Preview Or Illustration

Pre Event Context

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
fig15_precursor_test.png
Asset reference
acand_d68edacc-b197-56dd-b85d-4164c5f6aeb2
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. A null amplitude precursor does not rule out slow deformation. Terrain-matched random controls make threshold-adjacent p-values sensitive to sampling.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Primary Sentinel-1 series: 29 June–28 August 2026, 12-day cadence
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

02

Sentinel-1 change analysis — methods, dates, encoding and limitations

6269 bytes (source-listed)Markdown

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Metadata And Documentation

Not Applicable To Catalogued Role

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
README.md
Asset reference
acand_8ec48c8b-a262-58bf-b8f8-7a94baf3ba68
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. Documentation or access support for the parent resource.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Not stated
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. Assessment uses source metadata; full scientific-file structure was not established. Research code was not executed.

Evidence: source 1 · source 2 · source 3

03

Radar change over historical SRTM relief — Langtang Lirung comparison

2146294 bytes (source-listed)PNG

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Preview Or Illustration

Event Analysis

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
fig13_real_prepost.png
Asset reference
acand_d62fb292-66ec-5ba4-8593-fad446e5bc7d
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. The terrain in both panels is historical SRTM; only the radar tone changes. This is not post-collapse topography.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Sentinel-1 event pair: 16 and 28 August 2026
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

04

VV and VH backscatter-change comparison — Langtang Lirung figure

1471347 bytes (source-listed)PNG

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Preview Or Illustration

Event Analysis

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
fig12_vv_vh_confirm.png
Asset reference
acand_391a17f6-0c0f-5d67-ac73-9b05a7772b16
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. The asset’s content, provenance and use limits are recorded in its metadata assessment.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Sentinel-1 event pair: 16 and 28 August 2026
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

05

Seasonal VH backscatter comparison — 2025 and 2026 figure

262773 bytes (source-listed)PNG

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Preview Or Illustration

Historical Baseline

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
fig16_2025_baseline.png
Asset reference
acand_5f437bf7-a1ca-5e4b-a01e-73b914d3b447
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. The seasonal comparison uses a second acquisition orbit. It must not be mixed with the primary event pair as if viewing geometry were identical.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Second-orbit VH series: 3 June–26 August 2025 and 5 May–22 June 2026
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

06

VV radar backscatter before and after the cascade — Langtang Lirung figure

3507300 bytes (source-listed)PNG

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Preview Or Illustration

Event Analysis

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
fig11_s1_change.png
Asset reference
acand_c21d0aa3-3d0e-5683-a451-200714e1e5ac
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. The asset’s content, provenance and use limits are recorded in its metadata assessment.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Sentinel-1 event pair: 16 and 28 August 2026
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

07

VV backscatter change — Langtang Lirung, 28 minus 16 August 2026 (GeoTIFF)

16486485 bytes (source-listed)GeoTIFF

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Derived Or Compiled Data

Event Analysis

Data candidate · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

  • Establish the export’s radiometric encoding before quantitative reuse; source-inferred scaling is not independently calibrated here.
Catalogue details
Original source title
langtang_S1_change_dB.tif
Asset reference
acand_b2df5c2f-e686-59ad-b46b-884e299c0f09
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. The raster records VV backscatter change, not a mapped failure scar. Its dB conversion is inferred by the author and not absolutely calibrated; the 6 dB delineation threshold is arbitrary.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Sentinel-1 event pair: 16 and 28 August 2026
Spatial resolution
8.83024e-05 × 7.778216019e-05 degrees output grid; not an accuracy estimate
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

08

Sentinel-1 change and precursor analysis — Python source code

12768 bytes (source-listed)Python

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Source Code

Event Analysis

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
s1_langtang_analysis.py
Asset reference
acand_f7828b51-2191-51ad-bd30-650472edc7ff
Host / aggregator
zenodo.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. Source code was read as text only. Its reproducibility claims and outputs were not executed by this review.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Not stated
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Collection licence stated; asset rights need review — Source states CC-BY-4.0. Apply it only to the documented asset scope; separate upstream data and imagery terms remain applicable.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. Assessment uses source metadata; full scientific-file structure was not established. Research code was not executed.

Evidence: source 1 · source 2 · source 3

09

Sentinel-1 change and precursor analysis — DOI metadata, all-version concept record (JSON)

Not stated; zero in numeric field means unknownJSON

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Metadata And Documentation

Not Applicable To Catalogued Role

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
zenodo.22541071
Asset reference
acand_e4ed0d8c-3124-5c7b-a273-c6fe94269b5f
Host / aggregator
api.datacite.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. Documentation or access support for the parent resource.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Not stated
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Not stated — This JSON describes a DOI record. Its rights declarations concern the deposited resource; metadata-response reuse terms have not been separately charted.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3

10

Sentinel-1 change and precursor analysis — DOI metadata, version 1.0.0 (JSON)

Not stated; zero in numeric field means unknownJSON

Open source asset
Listed contributor

Sah, Ajay Kumar

Classification

Metadata And Documentation

Not Applicable To Catalogued Role

Supporting asset · Metadata assessed 8 September 2026

Reachable without registration · Direct Open · checked 8 September 2026

Catalogue details
Original source title
zenodo.22541072
Asset reference
acand_8210d09e-193d-53bf-adb2-7b10b860f81a
Host / aggregator
api.datacite.org
Relationship to record
Asset of Sentinel-1 change and precursor analysis. Documentation or access support for the parent resource.
Upstream source
Not stated or not resolved
Upstream evidence
Source attribution assessed; imported data and independently acquired observations remain distinct.
Dataset family
event_data_or_code
Acquisition date
Not stated
Spatial resolution
Not stated
Access result
Reachable without registration on 8 September 2026
Provenance
Under review
Rights
Not stated — This JSON describes a DOI record. Its rights declarations concern the deposited resource; metadata-response reuse terms have not been separately charted.
Redistribution
Metadata And Links Only; No Third-Party Asset Bodies Published By This Catalogue.
Production method
Automated metadata and technical assessment completed on 8 September 2026. File structure was inspected within the bounded transfer policy. Research code was not executed.

Evidence: source 1 · source 2 · source 3