Magnitude 1.9, Thu Jul 22 2021 5:10 PM

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PublicID 2021p546529
UTC Time 2021-07-22T05:10:31Z
Latitude -38.45 (± 8.0 km)
Longitude 175.97 (± 12.9 km)
Depth 135 km (± 20 km)
Depth Type free
Earth Model iasp91
Used Phase Count 12
Used Station Count 9
Standard Error 0.77 (s)
Azimuthal Gap 234.53 (degrees)
Minimum Distance 0.91 (degrees)


Type Magnitude Station Count
Preferred (M) 1.9  
MLv 1.9 1
M 1.9 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

-6.0-4.0- (s)0123Distance (degrees)Pick Residuals

Station Magnitudes (MLv) (degrees)Station Magnitudes (MLv)

Magnitude Residuals (MLv)

- (degrees)Magnitude Residuals (MLv)