M 4.0 - COOK STRAIT, NEW ZEALAND
A magnitude 4.0 earthquake struck near COOK STRAIT, NEW ZEALAND on Sunday, September 6, 2026. This light seismic event occurred at a focal depth of 166.0 km (intermediate focal depth), verified by GNS real-time seismic telemetry.
Seismic Telemetry Specifications
4.0ML
Light Seismic Class
166.0km
Upper Mantle
40.260° S, 173.483° E
GPS Coordinates
15 tons
TNT Equivalent Power
GNS
USGS Real-time Feed
Epicenter Location & Tectonic Fault Map
Is This Earthquake Dangerous?
A magnitude 4.0 event is classified as a light earthquake. Noticeable shaking of indoor objects and rattling doors/windows. Generally causes none to slight non-structural damage in older buildings.
Estimated Shaking Radius
~50–100 km
Potential Damage Zone
< 15 km (very minor)
Focal Depth Effect
Moderate Damping
What Does Magnitude 4.0 Mean?
Earthquake strength is measured on a logarithmic scale. Compare this event with the full seismic scale:
Logarithmic Energy Multiplier
Because seismic scales are logarithmic, each whole integer increase represents:
10× Ground Motion Amplitude
The seismograph wave amplitude jumps by tenfold for every 1.0 magnitude step.
~31.6× Radiated Kinetic Energy
Total energy release increases exponentially (101.5 ≈ 31.62 times per magnitude unit).
Why Did This Earthquake Happen?
New Zealand straddles the boundary between the Australian and Pacific tectonic plates. In the South Island, the Alpine Fault accommodates oblique strike-slip motion, while the Hikurangi Subduction Zone off the North Island generates subduction earthquakes along the southwestern edge of the Ring of Fire.
Originating at a depth of 166.0 km (Upper Mantle / Wadati-Benioff Zone (70–300 km)), this rupture occurred originated within the descending oceanic plate inside the upper mantle. shaking radiates over a wider geographic area with attenuated high frequencies.
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Earthquake Safety Action Plan
- •Drop, Cover, and Hold On: Take cover beneath a sturdy table or desk.
- •Stay indoors away from exterior glass windows and heavy unanchored fixtures.
- •If outdoors, move into an open area away from power lines and building facades.
- •Inspect utilities for damaged gas lines, water leaks, or electrical hazards.
- •Expect Aftershocks: Secondary tremors frequently strike after moderate and strong events.
- •Avoid damaged structures and listen to official emergency broadcasts.
- •Maintain a 72-hour emergency go-bag with water, non-perishable food, and first aid.
- •Anchor heavy furniture, water heaters, and appliances to structural wall studs.
- •Establish a family emergency communication protocol and meeting point.
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