Study Finds 2011 Japan Quake Shifted Country 5-6 Millimeters After Core Bounce
Updated
Updated · CNN · Jun 24
Study Finds 2011 Japan Quake Shifted Country 5-6 Millimeters After Core Bounce
3 articles · Updated · CNN · Jun 24
Summary
GPS data show nearly all of mainland Japan lurched 5 to 6 millimeters east about 15 minutes after the March 11, 2011 magnitude 9.0 quake, a small but permanent shift researchers say was previously overlooked.
Sunyoung Park's team concluded seismic waves traveled roughly 3,600 miles to Earth's core and back, then displaced four tectonic plates across an area about 1,800 miles long.
The broad movement was unlike localized quake damage: researchers say it was the widest such shift ever recorded and released energy comparable to a magnitude 7.5 earthquake, though spread thinly over a huge area.
The finding points to a new seismic hazard because core-reflected waves arrive on a roughly 15-minute delay, potentially making their effects more predictable than aftershocks.
Outside experts called the study significant, saying it suggests large earthquakes can keep disturbing fault systems in unexpected ways well after the main rupture, especially in places with monitoring networks as dense as Japan's.
With a 15-minute delay, can this newly discovered 'core-bounce' wave become the first predictable post-earthquake event?
A megaquake's echo from Earth's core can move a country. How does this rewrite our map of seismic hazards?
What other global seismic threats might be hiding in plain sight, dismissed as mere data glitches?
Redefining Earthquake Risk: The Discovery of Core-Reflected Wave-Triggered Slip and Its Global Seismic Hazard Implications
Overview
A groundbreaking scientific discovery published in June 2026 has redefined our understanding of earthquake aftermath by revealing a new type of seismic hazard. Researchers found that ground displacement and fault slip can occur even after the main shaking stops, as seismic waves continue to move the fault line. This means that significant events may be triggered minutes after an earthquake, not just during the initial shock. The discovery highlights the need for global awareness and improved preparedness, as communities must now consider the risk of delayed seismic events that extend beyond the immediate impact of earthquakes.