The alert level for Terceira’s Santa Barbara volcano has been raised to V3 and for the island’s fissure volcanic system to V1 due to seismic activity, according to the Azores Seismovolcano Monitoring Centre.
“Considering that since March 2024, seismic activity in the western sector of Terceira Island has clearly exceeded normal levels and has been accompanied by some signs of crustal deformation. [nos corpos rochosos]Due to facts indicating the occurrence of a magmatic intrusion at depth, the crisis office has decided to raise the alert level of the Santa Barbara volcano to V3 and the Terceira fissure volcanic system to V1,” says the website of the Center for Information and Seismic Volcanic Observation of the Azores (CIVISA ).
According to information available on the CIVISA website, volcanic alert levels V0 mean “resting” and V6 mean “ongoing eruption.”
Santa Barbara volcano was at level V2, which means possible reactivation of the system, now moving to the next level (confirmation of reactivation of the system).
According to the Institute of Volcanology of the University of the Azores (IVAR), the information obtained through the monitoring network managed by CIVISA allows us to verify that the seismovolcanic crisis registered on the island of Terceira since June 24, 2022, “continues, showing clear signs of increasing”.
During this crisis, seismic activity was concentrated “with greater frequency within the perimeter of the Santa Barbara volcano and was essentially characterized by the occurrence of microseisms.”
The most powerful earthquake occurred on January 14, 2024 at 7:19 local time with a magnitude of 4.5 on the Richter scale and an epicenter approximately one kilometer east of Serreta and was felt with a maximum intensity of VI on the scale. Modified Mercalli, in the western sector of the island.
At that time, according to CIVISA, “some cracks were recorded in houses with little resistance to seismic effects, the collapse of loose stone walls, damage to some communication routes and landslides inside the island and on the cliffs.”
On the Richter scale, earthquakes are classified by magnitude into micro (less than 2.0), very small (2.0-2.9), small (3.0-3.9), weak (4.0-4.9), moderate (5.0-5.9), medium (5.0-5.9), strong (6.0-6.9), large (7.0-7.9), important (8.0- 8.9), exceptional (9.0-9.9) and extreme (when above 10).
The Modified Mercalli scale measures the intensity of earthquakes.
According to the Portuguese Institute of the Sea and Atmosphere (IPMA), at intensity III, considered weak, the shock is felt inside the house and hanging objects swing, feeling “a vibration similar to that caused by the passage of heavy vehicles.”
On the other hand, CIVISA explains that the seismicity recorded also affected, although less frequently, the Terceira fissure volcanic system, especially in the area that crosses the Santa Barbara mountain range and extends to the vicinity of the golf club to the east.
The organization also said activity was occurring further south, east of the Santa Barbara volcano’s zone of influence, in the area between Cinco Ribeiras and Angra do Heroismo, “and out to sea, to the west and south of the island.”
“The phenomenon that affected the island of Terceira cannot be separated from the increase in seismic-volcanic activity that has occurred in the Azores region and in particular in the Central Group since the beginning of 2022,” he explains.
CIVISA accepts the possibility that events experienced by the public will continue to occur, the magnitude and intensity of which may exceed those recorded to date, taking into account the “observable pattern of activity”.
Author: Lusa
Source: CM Jornal
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