Magnitude 3.9, Fri Mar 5 2021 8:38 AM


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Origin


PublicID 2021p169779
UTC Time 2021-03-04T19:38:46Z
Latitude -37.51 (± 15.0 km)
Longitude 179.92 (± 15.3 km)
Depth 33 km (± 0 km)
Depth Type operator assigned
Earth Model iasp91
Used Phase Count 11
Used Station Count 9
Standard Error 0.50 (s)
Azimuthal Gap 327.04 (degrees)
Minimum Distance 1.23 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 3.9  
M 3.9 3

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


-2.0-1.00.01.02.0residual (s)012Distance (degrees)Pick Residuals