Magnitude 4.0, Fri May 19 2017 6:24 PM

Download Event Information



PublicID 2017p373693
UTC Time 2017-05-19T06:24:24Z
Latitude -39.97 (± 2.8 km)
Longitude 176.56 (± 2.8 km)
Depth 14 km (± 8 km)
Depth Type free
Earth Model iasp91
Used Phase Count 17
Used Station Count 9
Standard Error 0.54 (s)
Azimuthal Gap 76.11 (degrees)
Minimum Distance 0.13 (degrees)


Type Magnitude Station Count
Preferred (M) 4.0  
MLv 4.0 (± 0.2) 7
ML 4.4 (± 0.2) 7
M 4.0 7

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

-18.0-16.0-14.0-12.0-10.0-8.0-6.0-4.0- (s)01234Distance (degrees)Pick Residuals

Station Magnitudes (MLv) (degrees)Station Magnitudes (MLv)

Station Magnitudes (ML) (degrees)Station Magnitudes (ML)

Magnitude Residuals (MLv)

- (degrees)Magnitude Residuals (MLv)

Magnitude Residuals (ML)

- (degrees)Magnitude Residuals (ML)