Magnitude 1.8, Mon Oct 19 2020 9:23 AM



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Origin


PublicID 2020p788781
UTC Time 2020-10-18T20:23:00Z
Latitude -39.77 (± 17.7 km)
Longitude 175.09 (± 9.9 km)
Depth 28 km (± 8 km)
Depth Type free
Earth Model iasp91
Used Phase Count 12
Used Station Count 7
Standard Error 0.15 (s)
Azimuthal Gap 235.60 (degrees)
Minimum Distance 0.08 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 1.8  
ML 1.6 (± 0.3) 6
MLv 1.8 (± 0.3) 5
M 1.8 5

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)0Distance (degrees)Pick Residuals

Station Magnitudes (ML)


0.01.02.03.0Magnitude0Distance (degrees)Station Magnitudes (ML)

Station Magnitudes (MLv)


0.01.02.03.0Magnitude0Distance (degrees)Station Magnitudes (MLv)

Magnitude Residuals (ML)


-1.00.01.0Residual0Distance (degrees)Magnitude Residuals (ML)

Magnitude Residuals (MLv)


-1.00.01.0Residual0Distance (degrees)Magnitude Residuals (MLv)