A magnitude 1.7 earthquake was registered 29 miles north of Valdez, Alaska, on November 27, 2024, at a depth of 19 miles. Southern Alaska’s seismic activity is influenced by various tectonic features, including the megathrust fault and crustal seismicity from local faults. Significant historical earthquakes underline the need for awareness and preparedness in this geologically active region.
On November 27, 2024, an earthquake with a magnitude of 1.7 struck approximately 29 miles north of Valdez, Alaska, at 04:23:55 AKST (13:23:55 UTC). The seismic activity was recorded at a depth of 19 miles (30 km) and has not yet been reviewed by a seismologist. This event underscores the geological complexity of the southern Alaska region, where multiple tectonic features contribute to regular seismic occurrences.
The tectonic setting of Southcentral Alaska is characterized by varied seismic activity driven by both subduction and crustal processes. Earthquakes are predominantly caused by the megathrust fault located at the boundary of the Pacific and North American tectonic plates, with notable historical events including the 1964 Great Alaska Earthquake, the second-largest earthquake ever recorded at magnitude 9.2. Additionally, intermediate-depth seismicity occurs in the Wadati-Benioff Zone, where the subducting Pacific Plate moves downward into the earth’s mantle, affecting the region’s seismic behavior. Significant earthquakes such as the M7.1 events in Iniskin (2016) and Anchorage (2018) exemplify the impact of this subduction zone, causing notable ground shaking and damage.
A third source of seismicity in this area arises from crustal interactions among the geological structures of Cook Inlet basin, the Castle Mountain Fault, and a diffuse zone of seismicity extending to the Denali Fault. These formations are capable of producing substantial earthquakes, as evidenced by the April 1933 earthquake that caused extensive damage in Anchorage and the M5.6 Sutton Earthquake in 1984, linked to the Castle Mountain Fault. Overall, southern Alaska’s tectonic landscape is intertwined with several active faults and subduction dynamics, leading to its frequent seismic activity.
The regular occurrence of earthquakes in southern Alaska is intimately connected with its complex tectonic setting. The region is notably affected by the interaction of the subducting Pacific Plate and the North American Plate, leading to significant seismic events over the past century. The notable 1964 earthquake is a stark reminder of the destructive potential present in this area, highlighting the importance of understanding local seismicity for preparedness and risk management. Seismologists categorize earthquakes based on their depth and tectonic origin, with the Wadati-Benioff Zone being a critical region where the Pacific Plate descends. The study of past seismic events provides insights into the mechanisms and potential future risks associated with earthquakes in the area. Furthermore, detailed mapping of faults and historical earthquake data helps to inform both scientific research and public safety initiatives.
In summary, the 1.7 magnitude earthquake that occurred near Valdez on November 27, 2024, serves as a reminder of the geological activity prevalent in southern Alaska. The region’s seismicity, driven by its complex tectonic setting, particularly the interactions of the Pacific and North American plates, continues to pose significant challenges. By studying historical seismic events and their underlying mechanisms, scientists aim to enhance understanding and preparedness for future earthquakes in this seismically active area.
Original Source: earthquake.alaska.edu
