Magnitude 4.0, Tue Jan 16 2018 1:22 PM


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Origin


PublicID 2018p040583
UTC Time 2018-01-16T00:22:50Z
Latitude -43.48 (± 2.8 km)
Longitude 172.81 (± 5.8 km)
Depth 5 km (± 0 km)
Depth Type operator assigned
Earth Model iasp91
Used Phase Count 13
Used Station Count 9
Standard Error 0.20 (s)
Azimuthal Gap 151.51 (degrees)
Minimum Distance 0.26 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 4.0  
MLv 4.0 (± 0.1) 23
ML 4.3 (± 0.2) 7
M 4.0 23

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)01234567Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.04.05.0Magnitude12345Distance (degrees)Station Magnitudes (MLv)

Station Magnitudes (ML)


0.01.02.03.04.05.0MagnitudeDistance (degrees)Station Magnitudes (ML)

Magnitude Residuals (MLv)


-1.00.01.0Residual12345Distance (degrees)Magnitude Residuals (MLv)

Magnitude Residuals (ML)


-1.00.01.0ResidualDistance (degrees)Magnitude Residuals (ML)