2024 PNSN Earthquake Catalog
Figure 1. Map of Oregon and Washington showing the topography and bathymetry in grey scale and the 2024 detected earthquake epicenters as colored circles. The size of the circles indicate the magnitude of the earthquake and the color indicates the depth below sea level in km. Square shapes are events that were located by PNSN but were outside of our authoritative boundary.
In 2024 there were 3,272 earthquakes recorded by the Pacific Northwest Seismic Network across the states of Oregon and Washington, underscoring the region's dynamic seismic activity. This was a pretty typical year for the region. Most of these quakes were not felt. Their magnitudes ranged from a low -1.1 magnitude, minor tremors too small to be felt by people, to magnitude 3.5, which is strong enough to be felt but not cause any damage or injuries. Depths ranged from crustal events very close to the surface within the North American plate and events associated with Cascade volcanoes, between 0-30km, to events deep below the surface in the subducting slab of the Juan de Fuca plate roughly 30-60km deep and up to 80km in depth.
The spatial pattern shown in the top figure, is representative of the longer term seismicity patterns in the region. Despite the majority of these events being low in magnitude, the PNSN’s sensitive monitoring provides valuable insights into the underlying tectonic processes shaping the Pacific Northwest. The frequency and distribution of these earthquakes reflect the ongoing tectonic interactions between the Juan de Fuca, North American, and Pacific plates, which together create a complex seismic and volcanic environment.
The most significant earthquake to shake our region was actually an earthquake with its source off the coast of Northern California, the magnitude 7 Mendocino earthquake of December 5th, 2024. The seismic waves from this event were felt in Southern Oregon and ShakeAlert-powered alerts were sent to people’s cell phones and in schools and other places!
The 2024 earthquake catalog highlights the importance of earthquake preparedness and public awareness in the region. While no major seismic events were recorded during the year, the presence of numerous small to moderate quakes serves as a reminder of the potential for larger, more destructive events in the future. The PNSN's work is critical in maintaining a robust early-warning system, monitoring aftershock sequences, and cataloging seismicity which feeds into enhancing regional resilience to seismic and volcanic hazards. With over 3,000 recorded events, 2024's data further emphasizes the need for ongoing research, infrastructure strengthening, and community education on how to respond in the event of a larger earthquake in the Pacific Northwest.
Below are several graphics created using the public tools available on the PNSN.org Custom Search Page.
Figure2. Events M2.5 and greater. These events if shallow enough and near populated areas are large enough to be felt. 44 such events occurred within or very close to the PNSN authoritative boundary of Washington and Oregon. Events on the border of our region, such as the M4.0 event just to the west of the San Juan Islands are a good example of an event outside our authoritative boundary that could be felt by people within the boundary.
Figure 3. Profile from west to east. This shows hypocenters of earthquakes from the PNSN catalog by plotting their location with distance in km from west to east along the x-axis and their depth in km along the y-axis. The large cluster of events within the North American crust up to ~35 km in depth are associated with slow deformation of the Puget Sound region. The events trending downward west to east from roughly 20 km to >70 km are events along and within the subducting slab of the Juan de Fuca plate.
Figure 4. Cumulative number of earthquakes from January 1, 2024 through December 31, 2024. This graph tells us that on average over our whole authoritative region, and including even the smallest events, we detect several hundred earthquakes per month. The slight uptick at the end of September was due to a swarm of small earthquakes, the largest event being only Ml 2.9, just west of the Hanford Site,. The largest earthquake on this plot is from the M4.0 earthquake in the San Juan Islands in late September.