Catalog record
These fields are copied from the Smithsonian Global Volcanism Program Holocene volcano snapshot stored on this site. The file was fetched 2026-09-19T12:21:44Z. It is a location catalog, not a live alert.
- Catalog name
- St. Helens
- GVP number
- 321050
- Country
- United States
- Type
- Stratovolcano
- Elevation
- 2,549 m
- Region
- North America Volcanic Regions
- Subregion
- High Cascades Volcanic Arc
- Tectonic setting
- Subduction zone / Continental crust (> 25 km)
- Last-eruption year
- 2008
- Evidence code
- Eruption Observed
- Latitude, longitude
- 46.2, -122.18
Elevation rank in the High Cascades Volcanic Arc in this snapshot: 9 of 19. Rank is by the listed elevation only. It is not a hazard ranking.
How to read the last-eruption year
The year is a catalog field. A recent year means the snapshot recorded activity in that year. It is not an alert level, a size, or a statement about what happens next. Evidence codes in this file include “Eruption Observed” and “Eruption Dated.” Those are Smithsonian categories for how the eruption year was established, not a forecast flag.
Setting
The High Cascades sit above the Cascadia Subduction Zone, where USGS Fact Sheet 2025-3050 describes the Juan de Fuca plate being thrust beneath the North American plate. That sheet separates three earthquake types in the Pacific Northwest: deep earthquakes inside the slab, megathrust earthquakes on the plate interface, and shallow crustal earthquakes. Mount St. Helens is the volcanic arc, not the megathrust itself.
USGS uses the 1980 eruption of Mount St. Helens as the example of a VEI 5 eruption, with an ash volume of about 1 cubic kilometer. VEI is a way to compare eruptions that have already been described. It is not a schedule for this volcano. The snapshot’s last-eruption year for this row is 2008.
Inside these documented rectangles: Cascadia / W. North America coast. The rectangles are documented on the About page. They are a lat/lon belt, not an official plate polygon.
Other volcanoes in this subregion
Highest listed elevations in the High Cascades Volcanic Arc in this snapshot, excluding this volcano when it is already first:
- Rainier, 4,392 m, last-eruption year 1450.
- Shasta, 4,317 m, last-eruption year 1250.
- Adams, 3,742 m, last-eruption year 950.
Distance to published great-earthquake epicenters
The distances below use this volcano’s catalog coordinates and epicenters from the USGS list of the 20 largest earthquakes since 1900. They are spherical distances to points, not distances to a fault trace, and not a hazard score.
- 1964 M9.2 Great Alaska earthquake (1964-03-28 03:36 UTC) — 2,304 km from the catalog point.
- 1946 M8.6 Unimak Island, Alaska (1946-04-01 12:29 UTC) — 2,981 km from the catalog point.
- 1957 M8.6 Andreanof Islands, Aleutians (1957-03-09 14:23 UTC) — 3,866 km from the catalog point.
You can repeat the measurement for any coordinates on the distance to fault references tool.
What this page will not tell you
It will not tell you the next eruption time, the next earthquake on the neighboring trench, or an evacuation route. For U.S. volcano notices, use the USGS Volcano Hazards Program. For earthquakes, use the USGS event pages linked from Live Quakes. This site’s volcano map only draws the Holocene catalog.