Seismic record

Earthquakes Near Facilities: A Seismic Record Matched to a Registry

A moderate earthquake rarely makes the news. If its epicentre is a few kilometres from a port, a dam or a power plant you follow, it is still worth knowing about. Off-Nadir Delta reads the U.S. Geological Survey earthquake feed, keeps the earthquakes that have a registered facility close by, and lists those facilities with the distance to each. It is a record and a set of distances. It is not an estimate of shaking or damage.

See them on the Watchfloor API reference

Quick answer — what an earthquake near facilities is here

An earthquake near facilities is a U.S. Geological Survey earthquake record that has at least one registered facility close to its epicentre: within 25 km for magnitude 5.0 or more, 50 km for magnitude 5.5 or more, 100 km for magnitude 6.5 or more, at a depth of 70 km or less. Earthquakes of unknown depth are left out. Facilities are the ports, airports, military bases, energy and nuclear sites, dams, bridges and similar entries of the location registry; straits and sea areas are not counted. The record lists up to the 5 nearest facilities with the distance from the epicentre to each facility’s registered point. It does not say how strongly any facility was shaken, or that any was damaged or stopped. Records are events on the Watchfloor map under the category Earthquakes Near Facilities.

What is an earthquake near facilities?

The U.S. Geological Survey publishes earthquake feeds that are, in its words, “Updated every minute”, among them a feed of magnitude 4.5 and larger earthquakes and a feed of significant earthquakes (USGS: GeoJSON Summary Format). Each entry gives the magnitude, the time, and the position with depth.

The earthquakes USGS rates as significant already appear on the map as ordinary events. The ones below that line mostly do not, and most of them matter to nobody in particular. A few happen next to something: a refinery, a dam, a naval base. That is the case this record is for.

So the definition is a join, not a measurement by this product: an earthquake from the USGS feed, and the registered facilities within a set distance of its epicentre. The larger the earthquake, the farther the search reaches.

Which earthquakes are kept

Magnitude 5.0 or more: registered facilities within 25 km of the epicentre.
Magnitude 5.5 or more: registered facilities within 50 km of the epicentre.
Magnitude 6.5 or more: registered facilities within 100 km of the epicentre.
Depth of 70 km or less. Deeper earthquakes are left out, and so are earthquakes whose depth is not given: a missing depth is not treated as shallow.
Earthquakes below magnitude 5.0 are not kept, however close they are.
Earthquakes that USGS itself rates as significant are not recorded here. They are ordinary events on the map.
An earthquake with no registered facility inside its distance produces no record.
Straits and sea areas are not counted as facilities.

Earthquake records: U.S. Geological Survey (earthquake feeds). Facility positions: OpenStreetMap contributors and Wikidata. The match by distance is made by Off-Nadir Delta.

What a record states

The earthquake as USGS recorded it: magnitude, time, epicentre and depth.
Up to the 5 nearest registered facilities, with the kind of each.
The distance from the epicentre to each facility’s registered point.
How many more registered facilities are inside the distance, when there are more than those listed.

What it does not state

Shaking. The record does not say how strongly any facility was shaken. The distance bands decide what counts as near; they are not an estimate of ground motion.
Damage or a stoppage. Nothing in the record says a facility was damaged or stopped operating. That comes from reporting and imagery.
That the facility was the nearest thing. Only facilities in the registry are matched. A plant that is not registered is not listed.
That it was measured there. Each facility is linked as nearby, never as the place of a report or of a measurement.
A severity. These records carry no severity. An empty severity means not assessed, not minor.

A record, next to the reporting

A seismic record says where and how large. Reporting says what happened to people and buildings. The two come from different sources, and the map keeps them as different kinds of evidence.

An earthquake near facilities is its own event and is not merged into reporting about the same earthquake. Its title and summary are written by a fixed rule from the USGS record and the distances, not by a model.

Earthquakes near facilities over the API

These records are events, so they come back from the events endpoint with their category. A page costs 3 tokens.

curl "https://offnadir-delta.com/api/v1/signals?categories=quake_exposure" \
  -H "Authorization: Bearer ond_..."

Each one carries measured: true and measured_kind: quake_exposure. The same query works through the MCP tool query_signals. A reader for this kind alone is GET /api/v1/quake-exposures, and client.quake_exposures in the Python SDK. Parameters and response fields are in the API reference.

What each plan sees

On every plan, the Watchfloor map shows that an earthquake was recorded near registered facilities, when, and where. The marks are there without paying.

Its magnitude and depth, which facilities are near and how far each is from the epicentre are part of the full account of each event, in the app, through the Delta Agent and over the API. Pricing shows which plan opens it.

How It Works

Open the Watchfloor

These records are on the map next to reported events. To see only these, pick “Earthquakes Near Facilities” under Category in the filters.

Find the seismogram marks

Each mark, a seismogram trace, is one earthquake with at least one registered facility inside its distance.

Open one

Read the magnitude and depth, the facilities that are near and the distance to each.

Look for what followed

The record does not say what the earthquake did. Reporting and satellite imagery of the facility are where that comes from.

Frequently Asked Questions

What is an earthquake near facilities?▼

A U.S. Geological Survey earthquake record with at least one registered facility close to its epicentre: within 25 km for magnitude 5.0 or more, 50 km for magnitude 5.5 or more, 100 km for magnitude 6.5 or more, at a depth of 70 km or less. The record lists the nearest facilities and the distance to each.

Does it mean the facility was damaged?▼

No. The record states the earthquake as USGS recorded it and the distance from the epicentre to each facility’s registered point. It does not say how strongly any facility was shaken, or that it was damaged or stopped.

Why do the distances depend on magnitude?▼

The rule reaches farther for a larger earthquake. The bands are a rule for what counts as near. They are not a model of shaking, and a facility just outside a band is not thereby unaffected.

Which facilities are matched?▼

The facilities of the location registry: ports, airports, military bases, energy and nuclear sites, dams, bridges and similar entries. Straits and sea areas are not counted. A facility that is not in the registry is not matched.

Where are the large earthquakes?▼

Earthquakes that USGS itself rates as significant are ordinary events on the same map, in the natural disaster category, with reporting attached. This kind is for the moderate earthquakes below that line that happen close to a registered facility.

Why are deep earthquakes left out?▼

An earthquake deeper than 70 km is left out because depth reduces the shaking at the surface. An earthquake whose depth is not given is left out too, instead of being assumed shallow.

Is there an API?▼

These records are events: GET /api/v1/signals with categories=quake_exposure returns them, each with measured: true and measured_kind: quake_exposure, at 3 tokens a page. A reader for this kind alone is GET /api/v1/quake-exposures, and client.quake_exposures in the Python SDK; the API reference has the parameters.

What does each plan see?▼

Every plan sees that an earthquake was recorded near registered facilities, when, and where on the map. The magnitude and depth, the facilities and their distances are part of the full account of each event, which not every plan includes. The Pricing page shows which plan opens it.