Q COSTARICA — The South Pacific and Guanacaste are among the six areas where the highest seismic activity was recorded in Costa Rica during 2025, this is according to an analysis by the Volcanological and Seismological Observatory of the National University (OVSICORI-UNA).
According to the institution, the six areas with the highest seismicity were:
- Northern Guanacaste
- Dominical-Uvita
- Quepos
- Coto Brus
- Parque Nacional Juan Castro Blanco
- Tilarán
These six regions stood out for the number of recorded events, their frequency, and their contribution to the seismic momentum released during the year.
“Furthermore, each of these areas reflects different tectonic processes, ranging from plate subduction to internal crustal faulting,” the experts emphasized.
“The differences between these zones are due to the geometry of the plates, the type of active faults, and the way in which tectonic deformation is released in each region,” they added.
Northern Guanacaste
According to OVSICORI, this area is primarily associated with the subduction of the Cocos Plate beneath the continental margin, as well as with the internal deformation of the overriding block.
The earthquakes were distributed between shallow and intermediate depths, demonstrating the interaction between crustal faults and the subducted plate.
“Throughout the year, the region exhibited persistent activity, with monthly fluctuations linked to specific seismic sequences, superimposed on a background seismicity regime,” they explained.
Although low- to moderate-magnitude earthquakes predominated, some events contributed significantly to the regional energy balance.
Dominical–Uvita
In the South Pacific, the Dominical–Uvita seismogenic zone stood out for its particularly complex tectonic dynamics.
The report explains that this region reflects the interaction between the Cocos Plate, the Panama Microplate, and a fragmented continental margin.
“This situation favors the occurrence of dense and highly concentrated seismic swarms,” the institution noted.
Throughout the year, activity was not uniform. A very significant increase was recorded in November, associated with a seismic sequence off the coast of Uvita and Dominical.
Although not characterized by large individual earthquakes, this zone stood out for the accumulation of energy released through multiple earthquakes.
Quepos
The Quepos area maintained significant seismic activity throughout the year, although July was the most active month.
“This region of the Central Pacific is associated with both the subduction of the Cocos Plate and crustal faulting of the upper block,” the report states.
Most earthquakes were concentrated at shallow and intermediate depths, a condition that favors the perception of moderate-magnitude events by the population.
During 2025, Quepos registered persistent activity, with temporary increases linked to specific sequences.
Although small earthquakes predominated, some events contributed disproportionately to the regional seismic moment.
“This behavior highlights Quepos’s role as an area capable of generating regionally significant earthquakes, even though the total number of large-magnitude events is limited,” the specialists emphasized.
Coto Brus
The Coto Brus area was distinguished by a complex tectonic regime, where subduction, internal deformation of the upper block, and crustal faulting converge.
“Because of this, it becomes one of the most relevant areas in terms of seismic moment release during the year analyzed,” Ovsicori highlighted.
The region is closely linked to the interaction between the Cocos Plate, the Panama Microplate, and the country’s southern continental margin.
Although it did not present an exceptional number of large earthquakes, Coto Brus concentrated events that contributed a significant fraction of the seismic energy released. October was the most active month.
Parque Nacional Juan Castro Blanco
In the north of the country, the seismogenic zone associated with Juan Castro Blanco National Park showed a pattern clearly distinct from that of the Pacific regions.
According to Ovsicori, this area is dominated by active crustal faulting, with mostly shallow earthquakes at depths of less than 10 kilometers.
Furthermore, the activity is linked to volcanic-tectonic processes in the vicinity of the Platanar-Porvenir-Viejo Volcano massif.
“Throughout the year, short-duration seismic swarms with a high frequency of small events were recorded. Although each earthquake released little energy individually, their frequency made this area a significant source of local seismicity,” the report states.
August was the month with the highest number of recorded events.
Tilarán
Finally, the Tilarán area stood out for its predominantly shallow seismicity, associated with active crustal fault systems.
The report indicates that this region, located in the north-central part of the country, is controlled by volcanic arc processes. Seismic activity during 2025 was clearly episodic.
“A marked increase in events stood out during October, associated with a local sequence that included one of the most significant earthquakes of the year, widely felt in the region,” Ovsicori stated.
Although small earthquakes predominated, some events concentrated tectonic deformation in specific locations.