Magnitude 4.1, Tue Sep 20 2022 8:04 AM


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Origin


PublicID 2022p707671
UTC Time 2022-09-19T20:04:53Z
Latitude -28.88 (± 27.9 km)
Longitude -177.60 (± 77.4 km)
Depth 365 km (± 9 km)
Depth Type free
Earth Model iasp91
Used Phase Count 13
Used Station Count 9
Standard Error 1.18 (s)
Azimuthal Gap 343.72 (degrees)
Minimum Distance 0.48 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (mB) 4.1 (± 0.2)  
mB 4.1 (± 0.2) 4
Mw(mB) 3.1 (± 0.4) 1

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


-4.0-3.0-2.0-1.00.01.02.03.04.0residual (s)024681012Distance (degrees)Pick Residuals

Station Magnitudes (mB)


0.01.02.03.04.05.0Magnitude1113Distance (degrees)Station Magnitudes (mB)

Magnitude Residuals (mB)


-1.00.01.0Residual1113Distance (degrees)Magnitude Residuals (mB)