Magnitude 2.5, Mon Dec 27 2021 7:10 PM


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Origin


PublicID 2021p973667
UTC Time 2021-12-27T06:10:03Z
Latitude -35.49 (± 14.1 km)
Longitude 175.08 (± 13.2 km)
Depth 5 km (± 0 km)
Depth Type operator assigned
Earth Model iasp91
Used Phase Count 8
Used Station Count 6
Standard Error 0.60 (s)
Azimuthal Gap 235.92 (degrees)
Minimum Distance 0.75 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 2.5  
MLv 2.5 (± 0.2) 7
ML 2.4 (± 0.3) 6
M 2.5 7

GeoNet combines magnitudes into a summary magnitude, M, which consists of a weighted average of the individual magnitudes and attempts to be a best possible compromise between all magnitudes for a range of earthquake sizes. Summary magnitude for GeoNet is then defined as:

M = (2 * MLv + (0.4 * number_of stations(Mw(mB)) - 1) * Mw(mB)) / (2 + (0.4 * number_of_stations(Mw(mB)) - 1))

Where MLv is local magnitude calculated on the vertical component and Mw(mB) is a Mw estimation based of mB by Bormann and Saul (2008).

Origin Map


Map of New Zealand.

Map showing stations with picks used to locate the earthquake. Stations with picks that have a zero weight in the solution are shown as small grey circles. Those with a higher weight are shown as larger circles. The quake is shown by the largest circle.

Pick Residuals


-5.0-3.0-1.01.03.05.0residual (s)012Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.04.0Magnitude1Distance (degrees)Station Magnitudes (MLv)

Station Magnitudes (ML)


0.01.02.03.04.0Magnitude1Distance (degrees)Station Magnitudes (ML)

Magnitude Residuals (MLv)


-1.00.01.0Residual1Distance (degrees)Magnitude Residuals (MLv)

Magnitude Residuals (ML)


-1.00.01.0Residual1Distance (degrees)Magnitude Residuals (ML)