Magnitude 2.8, Mon Nov 20 2017 2:12 PM



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Origin


PublicID 2017p873108
UTC Time 2017-11-20T01:12:25Z
Latitude -37.65 (± 5.3 km)
Longitude 178.41 (± 8.4 km)
Depth 29 km (± 6 km)
Depth Type free
Earth Model iasp91
Used Phase Count 14
Used Station Count 9
Standard Error 0.25 (s)
Azimuthal Gap 219.74 (degrees)
Minimum Distance 0.12 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 2.8  
MLv 2.8 (± 0.2) 15
ML 3.1 (± 0.3) 7
M 2.8 15

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


-3.0-2.0-1.00.01.02.03.0residual (s)01234567Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.03.04.0Magnitude012Distance (degrees)Station Magnitudes (MLv)

Station Magnitudes (ML)


0.01.02.03.04.05.0Magnitude0Distance (degrees)Station Magnitudes (ML)

Magnitude Residuals (MLv)


-1.00.01.0Residual012Distance (degrees)Magnitude Residuals (MLv)

Magnitude Residuals (ML)


-1.00.01.0Residual0Distance (degrees)Magnitude Residuals (ML)