search_earthquakes_by_location

Find seismic activity near Swiss locations using coordinates. Filter earthquakes by radius, time period, and magnitude to monitor local geological events.

Instructions

Search for earthquakes near a geographic location using the Swiss Seismological Service (SED) FDSN API. Useful for finding seismic activity near a Swiss city, landmark, or custom coordinates.

Input Schema

TableJSON Schema

Name	Required	Description
`lat`	Yes	Latitude of the center point (decimal degrees, e.g. 46.9 for Bern)
`lon`	Yes	Longitude of the center point (decimal degrees, e.g. 7.5 for Bern)
`radius_km`	No	Search radius in kilometres (default: 50, max: 500)
`days`	No	Number of past days to search (default: 90, max: 365)
`min_magnitude`	No	Minimum magnitude filter (default: 0.5)
`limit`	No	Maximum number of results to return (default: 20, max: 100)

Implementation Reference

src/modules/earthquakes.ts:312-370 (handler)

The handler function that executes the search_earthquakes_by_location tool logic.

async function handleSearchEarthquakesByLocation(
  args: Record<string, string | number>
): Promise<string> {
  const lat = Number(args.lat);
  const lon = Number(args.lon);

  if (isNaN(lat) || isNaN(lon)) {
    throw new Error("lat and lon must be valid numbers");
  }

  const radiusKm = Math.min(Number(args.radius_km ?? 50), 500);
  const days = Math.min(Number(args.days ?? 90), 365);
  const minMag = Number(args.min_magnitude ?? 0.5);
  const limit = Math.min(Number(args.limit ?? 20), 100);

  // SED FDSN uses maxradius in degrees, not km. Convert: 1 degree ≈ 111.12 km
  const maxRadiusDeg = radiusKm / 111.12;

  const url = buildUrl(BASE, {
    latitude: lat,
    longitude: lon,
    maxradius: maxRadiusDeg,
    starttime: startTimeISO(days),
    minmagnitude: minMag,
    limit: limit,
    format: "text",
    orderby: "time",
  });

  const raw = await fetchFdsnText(url);

  if (!raw) {
    return JSON.stringify({
      count: 0,
      events: [],
      center: { lat, lon },
      radius_km: radiusKm,
      days_searched: days,
      min_magnitude: minMag,
      limit,
      source: "Swiss Seismological Service (SED), ETH Zürich",
      note: "No events found near the given location.",
    });
  }

  const events = parseFdsnText(raw);

  return JSON.stringify({
    count: events.length,
    center: { lat, lon },
    radius_km: radiusKm,
    days_searched: days,
    min_magnitude: minMag,
    limit,
    source: "Swiss Seismological Service (SED), ETH Zürich",
    api: "FDSN Event Web Service — http://arclink.ethz.ch/fdsnws/event/1/",
    events,
  });
}

src/modules/earthquakes.ts:93-126 (schema)

Input schema definition for the search_earthquakes_by_location tool.

name: "search_earthquakes_by_location",
description:
  "Search for earthquakes near a geographic location using the Swiss Seismological Service (SED) FDSN API. " +
  "Useful for finding seismic activity near a Swiss city, landmark, or custom coordinates.",
inputSchema: {
  type: "object",
  required: ["lat", "lon"],
  properties: {
    lat: {
      type: "number",
      description: "Latitude of the center point (decimal degrees, e.g. 46.9 for Bern)",
    },
    lon: {
      type: "number",
      description: "Longitude of the center point (decimal degrees, e.g. 7.5 for Bern)",
    },
    radius_km: {
      type: "number",
      description: "Search radius in kilometres (default: 50, max: 500)",
    },
    days: {
      type: "number",
      description: "Number of past days to search (default: 90, max: 365)",
    },
    min_magnitude: {
      type: "number",
      description: "Minimum magnitude filter (default: 0.5)",
    },
    limit: {
      type: "number",
      description: "Maximum number of results to return (default: 20, max: 100)",
    },
  },
},

src/modules/earthquakes.ts:383-385 (registration)

Tool call dispatching/registration within the module handler.

case "search_earthquakes_by_location":
  return handleSearchEarthquakesByLocation(args as Record<string, string | number>);
default:

mcp-swiss