Magnitude 1.7, Sun Sep 23 2018 1:56 PM


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Origin


PublicID 2018p716434
UTC Time 2018-09-23T01:56:09Z
Latitude -37.56 (± 6.3 km)
Longitude 177.21 (± 7.7 km)
Depth 5 km (± 5 km)
Depth Type free
Earth Model nz3drx
Used Phase Count 7
Used Station Count 4
Standard Error 0.35 (s)
Azimuthal Gap 164.60 (degrees)
Minimum Distance 0.04 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 1.7  
MLv 1.7 (± 0.1) 2
ML 2.1 (± 0.0) 3
M 1.7 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


-8.0-6.0-4.0-2.00.02.04.06.08.0residual (s)0Distance (degrees)Pick Residuals

Station Magnitudes (MLv)


0.01.02.0MagnitudeDistance (degrees)Station Magnitudes (MLv)

Station Magnitudes (ML)


0.01.02.03.0MagnitudeDistance (degrees)Station Magnitudes (ML)

Magnitude Residuals (MLv)


-1.00.01.0ResidualDistance (degrees)Magnitude Residuals (MLv)

Magnitude Residuals (ML)


-1.00.01.0ResidualDistance (degrees)Magnitude Residuals (ML)