Archives par mot-clé : Earthquake

only geology

Two of Greece’s most dangerous volcanoes share an underground link

by C. Graling, Sept 24, 2025 in ScienceNews

A January earthquake swarm exposed shared plumbing between Santorini and Kolumbo.

 

An intense swarm of earthquakes around Greece’s Santorini Island in January has revealed a fiery underground link between two neighboring and historically explosive volcanoes.

Analyses of seismic activity from June 2024 through February 2025, along with changes in the island’s surface elevation, suggest that the same well of magma feeding the Santorini volcano may also supply the submerged Kolumbo volcano, just seven kilometers away, researchers report September 24 in Nature.

Complex, shared magma plumbing systems can complicate the interpretation of earthquakes and signs of imminent eruptions, say Marius Isken, a geophysicist at the GFZ Helmholtz Centre for Geosciences in Potsdam, Germany, and colleagues. This study, they say, highlights the need for real-time, high-resolution monitoring to improve volcano warnings.

Santorini is known for a catastrophic volcanic eruption around 1560 B.C. that contributed to the end of the Minoan civilization and caused widespread devastation, including earthquakes, tsunamis and possibly a volcanic winter. Kolumbo is no slouch either, erupting most recently in A.D. 1650.

When a swarm of over 1,200 earthquakes rattled the region early this year, Greece declared a state of emergency, fearing an imminent eruption. Although no eruption ensued, the abundant quakes allowed Isken and colleagues to examine the subsurface and better understand how and where magma moved.

better to know...?, climate and geology

Claim: Melting glaciers contribute to Alaska earthquakes

by UNIVERSITY OF ALASKA FAIRBANKS, March 15, 2021 in WUWT

In 1958, a magnitude 7.8 earthquake triggered a rockslide into Southeast Alaska’s Lituya Bay, creating a tsunami that ran 1,700 feet up a mountainside before racing out to sea.

Researchers now think the region’s widespread loss of glacier ice helped set the stage for the quake.

In a recently published research article, scientists with the University of Alaska Fairbanks Geophysical Institute found that ice loss near Glacier Bay National Park has influenced the timing and location of earthquakes with a magnitude of 5.0 or greater in the area during the past century.

Scientists have known for decades that melting glaciers have caused earthquakes in otherwise tectonically stable regions, such as Canada’s interior and Scandinavia. In Alaska, this pattern has been harder to detect, as earthquakes are common in the southern part of the state.

Alaska has some of the world’s largest glaciers, which can be thousands of feet thick and cover hundreds of square miles. The ice’s weight causes the land beneath it to sink, and, when a glacier melts, the ground springs back like a sponge.

“There are two components to the uplift,” said Chris Rollins, the study’s lead author who conducted the research while at the Geophysical Institute. “There’s what’s called the ‘elastic effect,’ which is when the earth instantly springs back up after an ice mass is removed. Then there’s the prolonged effect from the mantle flowing back upwards under the vacated space.”

In the study, researchers link the expanding movement of the mantle with large earthquakes across Southeast Alaska, where glaciers have been melting for over 200 years. More than 1,200 cubic miles of ice have been lost.

Southern Alaska sits at the boundary between the continental North American plate and the Pacific Plate. They grind past each other at about two inches per year — roughly twice the rate of the San Andreas fault in California — resulting in frequent earthquakes.

….