Magnitude 4.0, Sun Aug 19 2018 2:29 PM


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Origin


PublicID 2018p621901
UTC Time 2018-08-19T02:29:09Z
Latitude -37.57 (± 10.4 km)
Longitude 175.41 (± 19.3 km)
Depth 347 km (± 13 km)
Depth Type free
Earth Model iasp91
Used Phase Count 10
Used Station Count 7
Standard Error 4.19 (s)
Azimuthal Gap 205.08 (degrees)
Minimum Distance 0.51 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 4.0  
MLv 4.0 (± 0.4) 2
M 4.0 2

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


-10.0-8.0-6.0-4.0-2.00.02.04.06.08.010.0residual (s)01234Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.04.05.0MagnitudeDistance (degrees)Station Magnitudes (MLv)

Magnitude Residuals (MLv)


-1.00.01.0ResidualDistance (degrees)Magnitude Residuals (MLv)