Magnitude 2.8, Thu Apr 15 2021 2:37 AM


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Origin


PublicID 2021p280025
UTC Time 2021-04-14T14:37:15Z
Latitude -38.77 (± 13.7 km)
Longitude 175.56 (± 19.7 km)
Depth 127 km (± 21 km)
Depth Type free
Earth Model iasp91
Used Phase Count 11
Used Station Count 6
Standard Error 0.51 (s)
Azimuthal Gap 252.85 (degrees)
Minimum Distance 0.83 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 2.8  
MLv 2.8 1
M 2.8 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


-2.0-1.00.01.02.0residual (s)0123Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.0MagnitudeDistance (degrees)Station Magnitudes (MLv)

Magnitude Residuals (MLv)


-1.00.01.0ResidualDistance (degrees)Magnitude Residuals (MLv)