Magnitude 2.0, Thu Dec 7 2017 2:07 PM



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Origin


PublicID 2017p919045
UTC Time 2017-12-07T01:07:37Z
Latitude -41.19 (± 7.8 km)
Longitude 172.75 (± 6.1 km)
Depth 141 km (± 9 km)
Depth Type free
Earth Model iasp91
Used Phase Count 18
Used Station Count 9
Standard Error 0.62 (s)
Azimuthal Gap 115.31 (degrees)
Minimum Distance 0.20 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 2.0  
MLv 2.0 (± 0.7) 4
M 2.0 4

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


-6.0-4.0-2.00.02.04.06.0residual (s)0123Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.0Magnitude012Distance (degrees)Station Magnitudes (MLv)

Magnitude Residuals (MLv)


-1.00.01.0Residual012Distance (degrees)Magnitude Residuals (MLv)