🌋 lahar-watch

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"Most lahars from Mount Rainier have started with eruptions — but one of them didn't.
The Electron Mudflow came without warning, without fire, without any sign at all.
It just came."

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Mount Rainier is the most dangerous volcano in the United States. Not because it's the most active — but because of what surrounds it. More than 80,000 people live inside its lahar-hazard zones. The river valleys that drain the mountain — Puyallup, Carbon, White River, Nisqually, Tahoma Creek — are home to cities, highways, ports, and 2.5 million people in the broader corridor. When Rainier moves, it won't give much notice.

lahar-watch is a real-time monitoring dashboard that tracks the sensor network standing between those communities and the mountain.

🔗 Live Dashboard → bdgroves.github.io/lahar-watch

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What Is a Lahar

A lahar is a volcanic mudflow — a fast-moving slurry of volcanic debris, rock, ash, and water that can travel over 100 mph on steep slopes and still move at 15–20 mph when it reaches the valley floor. They bury everything. Roads, bridges, neighborhoods, ports.

Rainier has buried the Puget Lowlands at least 11 times in the last 6,000 years. The Osceola Mudflow — 5,600 years ago — sent 3.8 cubic kilometers of material all the way to Commencement Bay in Tacoma. The modern city of Enumclaw, Buckley, Bonney Lake, Sumner, and Auburn are built on top of it.

The most recent large lahar, the Electron Mudflow (~1507 AD), came from a landslide on Rainier's weakened west flank. No eruption. No warning. The entire west side of the volcano is still potentially vulnerable to spontaneous collapse. The city of Orting sits directly in the Electron's path — built on top of the old mudflow deposits — with roughly 30 minutes of warning time if a similar event happens today.

The USGS estimates a 1-in-7 chance of a catastrophic lahar at Rainier in the next 75 years.

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The Sensor Network

The lahar detection system has been operating since 1998, when Pierce County Emergency Management and the USGS Cascades Volcano Observatory installed the first Acoustic Flow Monitors (AFMs) in the Carbon and Puyallup River valleys. Since 2017, a major modernization effort has replaced aging hardware with a new generation of Lahar Monitoring Stations (LMS) featuring:

• Broadband seismometers — continuous real-time ground motion at 100+ samples/sec
• Infrasound arrays (3-sensor) — detect low-frequency pressure waves from debris flows, triangulate direction and speed
• Tripwire arrays — physical breakwire triggered by lahar front passage
• Webcams — visual confirmation of events
• GPS receivers — track ground deformation preceding volcanic unrest

Data from each station transmits to the Washington State Emergency Operations Center and South Sound 911 within 10 seconds. Automated algorithms analyze the signal and trigger alerts. When a lahar is confirmed, AHAB sirens activate across the Puyallup River Valley — over 40 sirens strategically placed through the communities.

Most downstream communities receive 40 minutes to 3 hours of warning. Orting gets about 30. Ashford, inside the park, gets roughly 5.

In October 2025, the National Park Service approved 9 new monitoring stations on the southwest flank of the mountain — including two deliberately placed in the path of potential lahars. When those stations go dark, scientists calculate the lahar's speed from the time elapsed between failures.

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Pages

Page	What It Shows
Dashboard	Live sensor map, station status, stream gauges, USGS alert level
Seismic	Real 24h waveform images from 8 PNSN stations + seismicity table
Travel Time	Interactive lahar warning-time calculator by drainage, scenario, volume
Status	Pipeline health, API status, data freshness, CI/CD badge

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Data Sources

Source	Data	Endpoint
USGS HANS API	Volcano alert level, CVO notices	volcanoes.usgs.gov/hans-public/api
USGS Earthquake Hazards	M0.5+ seismicity within 50 km	earthquake.usgs.gov/fdsnws/event/1
USGS NWIS Water Services	Live stream gauge levels	waterservices.usgs.gov/nwis/iv
IRIS FDSN Station Service	Station availability (UW + CC networks)	service.iris.edu/fdsnws/station/1
IRIS timeseriesplot	24h waveform PNG images	service.iris.edu/irisws/timeseriesplot/1

All APIs are public and require no authentication.

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Seismic Stations Monitored

Station ID	IRIS Code	Location	Elevation	Drainage
MUIR	UW.RCM.HHZ	Camp Muir	10,100 ft	Summit
CR01	UW.RCS.EHZ	Camp Sherman	1,860 ft	Carbon River
WR02	UW.STOR.HHZ	White River	~3,000 ft	White River
TC04	UW.TDH.HHZ	Tahoma Creek	2,900 ft	Tahoma Creek
PARA	CC.PARA.BHZ	Paradise	5,400 ft	Nisqually
CRY5	CC.CRYS.HHZ	Crystal Mountain	5,800 ft	White River NE
NQ01	CC.MILD.BHZ	Nisqually / Longmire	2,100 ft	Nisqually
PUPY	UW.PUPY.EHZ	Puyallup Valley	580 ft	Puyallup

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Stream Gauges

Gauge	USGS Site	Drainage	Communities at Risk
Puyallup at Orting	12093500	Puyallup	Orting, Puyallup, Sumner, Tacoma
Carbon at Orting	12094000	Carbon	Orting, Buckley
White at Buckley	12099200	White River	Enumclaw, Auburn, Kent
Nisqually at McKenna	12089500	Nisqually	Eatonville, Yelm, Olympia area

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Getting Started

Install pixi — the project's single environment and task runner:

# Windows
winget install prefix-dev.pixi

# macOS / Linux
curl -fsSL https://pixi.sh/install.sh | bash

Clone and install:

git clone https://github.com/bdgroves/lahar-watch.git
cd lahar-watch
pixi install

Run the pipeline:

pixi run fetch          # fetch all data + helicorder images → data/
pixi run status         # fetch + print live status table in terminal
python scripts/fetch_sensors.py --no-heli   # fast fetch, skip images
python -m http.server 8080                  # serve dashboard at localhost:8080

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How the Pipeline Works

GitHub Actions (06:00 + 18:00 UTC daily)
        │
        ├── pixi run fetch
        │     ├── USGS HANS API      → data/volcano_alert.json
        │     ├── USGS Earthquake    → data/seismicity.json
        │     ├── USGS NWIS          → data/stream_gauges.json
        │     ├── IRIS FDSN          → data/station_status.json
        │     ├── IRIS timeseriesplot → data/helicorders/*.png
        │     └── summary            → data/summary.json
        │
        ├── pixi run validate
        │
        ├── git commit data/*.json data/helicorders/*.png
        │
        └── Deploy to GitHub Pages
                  │
                  └── index.html loads data/*.json on page load
                      auto-refreshes every 5 minutes

The dashboard is pure static HTML/JS — no server, no backend. It reads JSON files committed to the repo by the Actions pipeline and renders them client-side.

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Repo Structure

lahar-watch/
├── index.html              # Main dashboard
├── seismic.html            # Live helicorders + seismicity
├── travel-time.html        # Lahar warning-time calculator
├── status.html             # Pipeline health + API status
├── pixi.toml               # Environment + task runner
├── scripts/
│   ├── fetch_sensors.py    # Main data pipeline (5 APIs)
│   └── validate_data.py    # JSON validation for CI
├── data/
│   ├── summary.json
│   ├── volcano_alert.json
│   ├── seismicity.json
│   ├── stream_gauges.json
│   ├── station_status.json
│   ├── helicorders.json
│   └── helicorders/        # 8x PNG waveform images
│       ├── MUIR.png
│       ├── CR01.png
│       └── ...
├── docs/
│   └── sensor-network.md   # Detailed sensor network reference
└── .github/
    └── workflows/
        └── deploy.yml      # Fetch + deploy Actions workflow

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Warning Windows by Community

Based on USGS lahar inundation models for a 0.5 km³ eruption scenario:

Community	Drainage	Distance	Warning Time	Population
Ashford (park)	Puyallup / Nisqually	8 km	~8 min ⚠	1,200
Orting	Puyallup / Carbon	56 km	~33 min ⚡	8,000
Buckley	Carbon / White	72 km	~44 min ⚡	4,800
Bonney Lake	Puyallup	80 km	~55 min ⚡	21,000
Enumclaw	White River	48 km	~38 min ⚡	12,000
Auburn	White River	78 km	~62 min ✓	87,000
Puyallup City	Puyallup	98 km	~82 min ✓	43,000

The interactive calculator at /travel-time.html lets you adjust drainage, scenario type (eruption / west-flank collapse / rapid onset), and volume from 0.01 km³ to 4 km³ (Osceola scale).

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Background Reading

• USGS: Monitoring Lahars at Mount Rainier
• Pierce County Outdoor Warning System
• PNSN: Mount Rainier Volcano Page
• USGS: Lahars and Debris Flows from Mount Rainier
• Seismological Society: Lahar Detection System Upgraded

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License

MIT — all data is public domain (USGS / federal government sources).
Built by @bdgroves.