Summary plots of catalogued events since 2007: Central North Island (taupo.pdf), Central NZ (wellington.pdf), Canterbury-Westland (canterbury.pdf) and Fiordland (fiordland.pdf). The magnitudes of events originating from the SeisComp3 system (events after 1 Jan 2012) are inconsistent with those from CUSP (events before 1 Jan 2012). Using magnitude cut-offs of 3.0 and 2.6 for CUSP and SeisComp3 based events, respectively, gives similar annual counts of event numbers. The catalogue is incomplete for smaller magnitude events.
Historical events since 1840 with magnitude ≥ 6 have been plotted (historical.pdf). The catalogue almost certainly has a deficit of tabulated events in this magnitude range prior to 1920, and probably at some other times too (see the cusum plot on Page 4).
This is part of a research project to develop and test the efficacy of stochastic models for earthquake probability forecasts. While such models show considerable promise, they still have many deficiencies. The ETAS model is specified by its intensity function (instantaneous rate), which can be displayed as a movie.
Currently, forecasts are made every 2nd Tuesday at 00:00hr (UTC) for 28 days. The most recent NZ forecast is given as a probability distribution in counts.pdf (pp 1–4, blue distributions) of event counts during the 28 days, and as a spatial rate over NZ in spatial.pdf. The probability distribution is for the rectangular region shown in the spatial rate plot. A graphical summary of seismic activity in the 100 days prior to the most recent forecast can be seen in eda.pdf. Full details of previous NZ forecasts are available on the GNS ftp website until that of 2019-09-22 12:00 (UTC), and on Google Drive (uses tinyurl.com) since then.
At the end of each forecast time interval, the forecast is assessed as in summary.pdf by comparing the outcome (red point) with the forecast. It can be seen that the model is under-forecasting after large events and over-forecasting during more benign periods. Missing data after large events causes the model to under-estimate the number of aftershocks during this time; and consequently, over-estimate event numbers during periods of benign seismicity. This problem is further exacerbated by magnitude inconsistencies in the NZ catalogue, see details of the ssNZ package. Solutions for these problems are currently being worked on.
Forecasts are made by utilising all recorded events up to the start of the forecast time interval, and then simulating the model over the forecast time interval. This is repeated many times, enabling the calculation of an empirical representation of the forecast probability distribution. Further details are given on the technical details page.
| Event | Date (UTC) | M | Forecasts/Plots | |||||
|---|---|---|---|---|---|---|---|---|
| Kaikoura | 2016-11-13 | 11:03 | 7.8 | GNS ftp dir | ||||
| Te Araroa | 2016-09-01 | 17:14 | 7.1 | GNS ftp dir | ||||
| St Arnaud | 2015-04-24 | 03:37 | 6.2 | |||||
| East of East Cape | 2014-11-16 | 22:33 | 6.5 | |||||
| Eketahuna | 2014-01-20 | 02:53 | 6.2 | |||||
| Seddon 2 | 2013-08-16 | 02:31 | 6.5 | |||||
| Seddon 1 | 2013-07-21 | 05:09 | 6.5 | seddon2013.pdf | ||||
| Pegasus Bay | 2011-06-13 | 02:21 | 6.0 | |||||
| Christchurch | 2011-02-21 | 23:51 | 6.2 | |||||
| Darfield | 2010-09-03 | 16:35 | 7.2 | chch.pdf | ||||
| Dusky Sound | 2009-07-15 | 09:22 | 7.8 | |||||
| Gisborne | 2007-12-20 | 07:55 | 6.7 | |||||
| Puysegur Trench | 2004-11-22 | 20:26 | 7.1 | |||||
| Fiordland | 2003-08-21 | 12:13 | 7.0 | |||||
| East Cape | 2001-08-21 | 06:51 | 7.1 | |||||
| Bay of Plenty | 1997-02-27 | (swam) | 5.6 | |||||
| Offshore East Cape | 1995-02-05 | 22:51 | 7.0 | |||||
| Bay of Plenty | 1994-12-15 | 11:20 | 6.0 | |||||
| Arthur's Pass | 1994-06-18 | 03:25 | 6.7 | |||||
| Secretary Island | 1993-08-10 | 00:52 | 6.7 | |||||
| Hawks Crag Westport | 1991-01-28 | 12:58 | 6.3 | |||||
| Weber II | 1990-05-13 | 04:23 | 6.3 | |||||
| Edgecumbe | 1987-03-02 | 01:43 | 6.1 | |||||
| Bay of Plenty | 1984-12-28 | (swam) | 6.3 | |||||
| Puysegur Bank | 1979-10-12 | 10:25 | 6.5 | |||||
| Milford Sound | 1976-05-04 | 13:56 | 6.5 | |||||
| Inangahua | 1968-05-23 | 17:24 | 6.7 | |||||
| Wairarapa 2 | 1942-08-01 | 12:34 | 6.8 | |||||
| Wairarapa 1 | 1942-06-24 | 11:16 | 6.9 | |||||
| Pahiatua | 1934-03-05 | 11:46 | 7.2 | |||||
| Hawke's Bay 2 | 1931-02-13 | 01:27 | 7.3 | |||||
| Hawke's Bay 1 | 1931-02-02 | 22:47 | 7.4 | |||||
| Murchison | 1929-06-16 | 22:48 | 7.3 | |||||
| Arthur's Pass | 1929-03-09 | 10:50 | 7.0 | |||||
| Cheviot | 1901-11-15 | 20:15 | 6.8 | |||||
| North Canterbury | 1888-08-31 | 16:45 | 7.0 | |||||
| Waipukurau | 1863-02-22 | 13:00 | 7.5 | |||||
| Wairarapa | 1855-01-23 | 09:32 | 8.2 | |||||
| Marlborough | 1848-10-15 | 14:10 | 7.4 | |||||
| Ruahine Range | 1843-07-08 | 05:30 | 7.6 | |||||
Data are sourced from GeoNet NZ. Also see The Encyclopedia of NZ and 10.1177/8755293019878190 Fig 2.
Global seismicity is summarised as an epicentral plot (world.pdf) of global events with magnitude ≥ 6 between 1964 and 2010. Data are taken from the PDE Catalogue and the selected magnitude is calculated as max(mb, Ms).