A Nine-Day Seismic Phenomenon That Was Missed by the World’s Eyes

Global Earth Tremors Linked to Greenland’s Mega-Tsunami

An unprecedented seismic signal, detected across the globe beginning in September 2023, has been definitively linked to a massive landslide in Greenland’s remote Dickson Fjord. The event generated a 200-meter-high mega-tsunami, sending vibrations through the Earth’s crust for nearly ten days.

The Mysterious Signal

Scientists initially labelled the unusual signal as an “unidentified seismic object” (USO) due to its distinct characteristics. Unlike typical earthquake rumblings, it presented as a single-frequency hum detected from both the Arctic and antarctic regions. Researchers at University College London and the Geological Survey of denmark and greenland were among the first to investigate the phenomenon.

Landslide and Tsunami Trigger

Detailed analysis, including satellite imagery and seismological data, revealed that the vibrations stemmed from a critically important rockslide in East Greenland. An estimated volume of rock equivalent to 10,000 Olympic swimming pools plunged into the Dickson Fjord on September 16, 2023, initiating the colossal tsunami. This event was directly linked to glacial thinning spurred by ongoing climate change.

The resulting tsunami was exceptionally large, reaching a height comparable to 136 stacked versions of Danny DeVito or slightly taller than Seattle’s space Needle. Experts suggest this event represents the largest wave observed since 1980.

The Phenomenon of Seiches

The prolonged nature of the seismic waves was explained by a phenomenon known as a seiche. This occurs when a large body of water, in this case, the icy fjord, experiences repeated sloshing back and forth. The fjord continued to oscillate over 10,000 times during the nine-day period.This is the first instance of this type of water movement being recorded as vibrations traveling across the Earth’s crust.

Event	Date	Location	Key Measurement
Landslide	September 16, 2023	Dickson Fjord, greenland	Volume of rock: Equivalent to 10,000 Olympic swimming pools
Tsunami Height	September 16, 2023	Dickson Fjord, Greenland	200 meters (656 feet)
Seismic Signal Duration	September 2023	Global	9 days

Did you Know? Seiches aren’t limited to fjords. They can occur in enclosed or semi-enclosed bodies of water like lakes, bays, and even swimming pools, frequently enough triggered by wind or seismic activity.

Satellite Confirmation and Climate Change Link

Further validation of the seiche’s role came from data collected by the Surface Water Ocean Topography (SWOT) satellite.Observations confirmed the sustained back-and-forth sloshing within the fjord, aligning with the timeframe of the seismic signals. The research underscores a growing trend: climate change is creating previously unseen and unpredictable geological extremes.

Pro Tip: stay informed about climate change and its potential impacts on our planet. Organizations like the IPCC (Intergovernmental Panel on Climate Change) provide vital data and insights.

Thomas Monahan, of the University of Oxford, stated that advanced satellite technologies are crucial for monitoring these rapidly changing phenomena, particularly in remote regions like the Arctic, where traditional sensor networks are limited.

The Increasing Frequency of Extreme Events

This event highlights a concerning trend toward more frequent and intense geological hazards linked to climate change. As glaciers continue to melt and destabilize, the risk of landslides and subsequent tsunamis is expected to increase. The incident serves as a stark reminder of the interconnectedness of Earth’s systems and the far-reaching consequences of a warming planet. The Greenland ice sheet is losing mass at an accelerating rate,with estimates suggesting a loss of approximately 280 gigatonnes per year between 2002 and 2020 (National Snow and Ice Data Center,2023).

Frequently Asked Questions About the Greenland Tsunami

• What caused the global seismic signal? A massive landslide in Greenland’s Dickson fjord triggered a 200-meter-high tsunami, creating vibrations that travelled around the world.
• How long did the seismic vibrations last? The vibrations persisted for approximately nine days, due to the repeated sloshing of water within the fjord (a seiche).
• what role did climate change play in this event? Climate change-induced glacial thinning destabilized the rock formations, predisposing the area to landslides.
• Is this type of event common? No, this is the first time a seiche has been recorded as vibrations through the Earth’s crust on a global scale.
• How was the tsunami confirmed? Both seismological data and satellite observations from SWOT confirmed the existence and characteristics of the tsunami.

What are your thoughts on the increasing impacts of climate change on geological events? Share your comments below!

What does the Kermadec Trench microseism swarm suggest about the limitations of current global seismic monitoring networks?

The 2015-2016 Microseism Swarm in the Kermadec Trench

Between September 2015 and January 2016, a remarkably unusual seismic event unfolded in the Kermadec Trench, a largely unexplored and remote oceanic trench northeast of New Zealand. This wasn’t a single, massive earthquake, but a sustained, nine-day-long swarm of very low-frequency seismic signals – a microseism swarm – that baffled geophysicists. While not posing a direct threat to populated areas, its characteristics and the reasons behind it remain a meaningful puzzle in the field of seismology and deep Earth studies.This event highlights the limitations of current global seismic monitoring networks and the potential for undetected geological activity.

Understanding Microseisms and Seismic Swarms

Before diving into the specifics of the Kermadec Trench event, it’s crucial to understand the terminology.

Microseisms: These are continuous, low-amplitude seismic vibrations of the Earth. Typically,they are generated by ocean waves interacting with the seafloor. However, the signals detected in the Kermadec Trench were distinctly not typical ocean-wave generated microseisms.

seismic Swarm: A sequence of earthquakes occurring in a localized area over a relatively short period, without a clear mainshock. Unlike a typical earthquake sequence with a dominant event, swarms consist of numerous earthquakes of similar magnitude.

Low-Frequency Signals: The signals detected were exceptionally low in frequency, meaning they had long wavelengths. This characteristic is crucial because low-frequency waves can travel vast distances through the Earth.

The Kermadec Trench: A Geological hotspot

The Kermadec Trench is one of the deepest oceanic trenches in the world, formed by the subduction of the Pacific Plate beneath the Australian Plate. This subduction zone is known for its intense seismic and volcanic activity. Though, the 2015-2016 event wasn’t a typical subduction-related earthquake. The trench’s remote location – far from densely populated areas and comprehensive seismic monitoring stations – contributed to the initial lack of widespread awareness. Studying this region is vital for understanding plate tectonics, mantle dynamics, and earthquake generation.

The Nine-Day Anomaly: What Happened?

The microseism swarm began around September 18,2015,and continued for approximately nine days. Here’s a breakdown of key observations:

1. Unusual Signal Characteristics: The signals were distinctly different from typical ocean-wave microseisms. They were more coherent and persistent.
2. Deep Source: Analysis suggested the source of the signals was located deep within the mantle, approximately 50-70 kilometers below the seafloor. This depth is unusual for typical earthquake activity in this region.
3. Low Magnitude: While continuous, the individual seismic events within the swarm were of very low magnitude, making them difficult to detect with conventional seismic networks.
4. Global Network Detection: The signals were detected by a network of global seismic observatories, including those operated by the Incorporated Research Institutions for Seismology (IRIS).
5. Lack of Correlation with Known Events: The swarm didn’t correlate with any known volcanic eruptions, large earthquakes, or human activities.

Potential Explanations and Ongoing Research

The cause of the Kermadec Trench microseism swarm remains a subject of ongoing research. Several hypotheses have been proposed:

Mantle Plume Interaction: One theory suggests the swarm was caused by the interaction of a mantle plume – an upwelling of abnormally hot rock from deep within the Earth – with the subducting Pacific Plate.

Fluid Migration: Another possibility is that the signals were generated by the movement of fluids (water or magma) within the mantle.

Deep Earthquakes: While the events were low magnitude, they could represent a series of very small, deep-focus earthquakes.

* Complex Subduction Processes: The swarm might be a manifestation of complex and poorly understood processes occurring within the subduction zone.

The Importance of Improved Seismic Monitoring

The Kermadec Trench event underscores the need for improved global seismic monitoring networks, particularly in remote and under-sampled regions. Current networks are frequently enough optimized for detecting large, shallow earthquakes that pose immediate threats to populated areas. However, events like