Reading Indonesia’s volcanic skies

Data pipelines, retained source evidence and a standalone interactive explorer behind Reading Indonesia’s volcanic skies. Replay Anak Krakatau’s September 2026 satellite scans alongside ash advisories and airport reports, compare six volcanoes, and explore a dated national directory.

The article uses native Svelte figures in caleb-tutty.com. This repository contains the Python processing pipeline and React/TypeScript research interface. You can run it without the website checkout, API keys, or downloading the original satellite bands. See the article alignment guide for the figure-to-code mapping and differences between the interfaces.

Run locally

Use Node.js 22.12 or newer (Node 22 is recorded in .nvmrc) and npm.

git clone https://github.com/tuttinator/volcano-vis.git
cd volcano-vis
npm ci
npm run dev

Open http://127.0.0.1:4178/?view=replay. The navigation also offers the advisory explorer, editorial story, volcano comparison and national directory. Rendered imagery is included: public/ is approximately 238 MB. Scientific assets and coastlines are served locally.

This is a retrospective explanation, not an operational warning service. An absent polygon does not establish that the air was clear of ash; Ash RGB does not measure ash concentration. Source times, gaps and corrections remain explicit.

Reproduce and verify

npm test                 # Rules, contracts, provenance and committed image checksums
npm run build            # Type-check and build the standalone app
npm run data:build       # Rebuild factual catalogs offline; requires Python 3.10+
npm run test:pipelines   # Export integration checks; Python standard library only

Default tests work on a fresh clone. For optional raw-band checksum verification, restore approximately 6.3 GB of inputs, then run npm run test:raw. Default tests still verify every committed Ash RGB PNG and its input metadata; the raw test fails if any recorded band is absent or corrupt.

For browser checks:

npx playwright install chromium
npm run test:browser
npm run build:embed
npm run test:embed

TEST_PRODUCTION=1 npm run test:browser checks an existing production build. Set PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH to use an installed Chromium executable.

The reproduction guide distinguishes rebuilding retained facts, retrieving provider images, processing satellite data, and exporting the article bundle. The pinned satellite Python environment is only needed for Ash RGB processing.

Export the article data

Install WebP command-line tools (cwebp on PATH), then:

npm run site:export                         # Writes site-export/ in this repository
npm run site:export -- --output /tmp/volcanic-ash
# Optional: explicitly target a local website checkout
npm run site:export -- --site ../caleb-tutty.com

The approximately 22 MB bundle contains replay, comparison and directory JSON, coastlines, a legend and WebP frames. --skip-images exports metadata only and does not produce a complete viewable bundle. Coordinates are rounded and WebP is lossy; use original manifests and PNGs for analysis.

What is included

Material	Coverage
Darwin VAAC advisories	104 editions, 470 geometries, six volcanoes; corrections retained
Himawari Band 13 and derived Ash RGB	579 frames each, 10 source gaps across 589 ten-minute slots, 4–8 September 2026
VIIRS daily crops	26 images, including Merapi in March 2023 and Semeru in November 2025
National directory	All 127 rows of MAGMA’s Type A/B/C table, updated 20 September 2021

Coverage is partial and asynchronous. The earliest retained Krakatau advisory is 5 September 2026 at 13:30 WIB; imagery begins before it. Original airport NOTAMs are missing: the track distinguishes scheduled closure, expiry and reported reopening using report-level evidence. The directory is a historical classification table, not a current alert inventory.

Repository guide

Path	Purpose
apps/web/src/	React interface and temporal selection rules
pipelines/	Factual builders, imagery retrieval, Ash RGB processing, article export
data/raw/	Retained snapshots and provenance; downloaded HSD bands are ignored
public/data/	Built catalogs, event contracts, imagery and checksums
schemas/, tests/	Data contracts, scientific display rules, browser and pipeline checks
docs/, plans/	Methods, inventories and historical design records

Start with reproduction, article alignment, source inventory, and Ash RGB methods. Earlier blog options, article draft, and completion audit are historical design records; the website repository holds the current article text.

Contributing and reuse

See CONTRIBUTING.md for checks and source-data conventions. Original code and documentation are MIT licensed. Third-party data, source pages and imagery are not covered by MIT; see DATA_LICENSE.md. The retained reuse review records unresolved redistribution questions. Code licensing does not clear the bundled data for public release.