Magnitude 2.7, Mon Mar 22 2021 5:57 AM


Download Event Information


Origin


PublicID 2021p215422
UTC Time 2021-03-21T16:57:36Z
Latitude -40.65 (± 4.7 km)
Longitude 175.83 (± 3.7 km)
Depth 24 km (± 9 km)
Depth Type free
Earth Model iasp91
Used Phase Count 12
Used Station Count 7
Standard Error 0.36 (s)
Azimuthal Gap 142.21 (degrees)
Minimum Distance 0.12 (degrees)

Magnitudes


Type Magnitude Station Count
Preferred (M) 2.7  
ML 1.0 (± 0.3) 6
MLv 2.7 (± 1.6) 3
M 2.7 3

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


-20.0-18.0-16.0-14.0-12.0-10.0-8.0-6.0-4.0-2.00.02.04.06.08.010.012.014.016.018.020.0residual (s)01Distance (degrees)Pick Residuals

Station Magnitudes (ML)


0.01.02.0MagnitudeDistance (degrees)Station Magnitudes (ML)

Station Magnitudes (MLv)


0.01.02.03.04.05.0Magnitude1Distance (degrees)Station Magnitudes (MLv)

Magnitude Residuals (ML)


-1.00.01.0ResidualDistance (degrees)Magnitude Residuals (ML)

Magnitude Residuals (MLv)


-2.0-1.00.01.02.0Residual1Distance (degrees)Magnitude Residuals (MLv)