Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
5
Summary
In the Hazard, Building Damage and Risk Assessment of November 2017 (Ref. 1), the seismic risk for a 24 Bcm/year
production scenario was presented. In a letter to Parliament (Ref. 2) the Minister of Economic Affairs and Climate
Policy presented a new production scenario, “Basispad Kabinet”, which shows a reduction in production from the
Groningen field, ultimately leading to cessation of production by 2030.
In this document, using the same workflow and models as used in Ref. 1, a seismic hazard and risk assessment for
the production scenario “Basispad Kabinet” is presented. The required deliverables from the Hazard and Risk
Assessment were specified in the Expectation Letter (Verwachtingenbrief) (Ref. 3) which the Minister of Economic
Affairs and Climate Policy sent to NAM on 2
nd
May 2018. In this Expectation Letter, in addition to the Hazard and
Risk Assessment report also an Operational Strategy for gas-year 2018/2019 was requested which contains the
operational implementation of the production strategy for the Groningen System (Ref. 7). Together with this Hazard
and Risk Assessment, a document “Bouwstenen voor Operationele Strategie Groningenveld 2018/2019” will be
submitted.
Taking into account the Wijzigingsbesluit (Ref. 4), the insights obtained in the Optimisation Study (Ref. 5) and the
Advice to the Minister by SodM (Ref. 6) production forecasts were made for scenario “Basispad Kabinet” based on
average temperature years, cold temperature years and warm temperature years. As a result of the declining
production from the Groningen field, the seismic event rate and the hazard will reduce over time. For instance, the
chance of an earthquake with a magnitude larger than M
L
=3.6 (the magnitude of the Huizinge earthquake) is
expected to reduce to some 7% per year by 2023. For reference, in the Risk Assessment of November 2017, which
was based on a production scenario of 24 Bcm/year, this was expected to be more than 20% per year by 2023. The
same reduction is also reflected in the hazard maps. The largest PGA in the hazard map (based on a 475 return-
period) is expected to decline from the current 0.18 g to 0.11 g (the largest PGA measured to date) by 2031. However,
the hazard will not reduce equally over the field. In the later years, the hazard is primarily located in the area North-
East of Loppersum. This is consistent with the equilibration of reservoir pressures during these later years. The gas
from the higher-pressure area to the North-West of Loppersum will continue to flow to the lower pressure South-
Eastern area, causing a continued decrease of pressure in this area.
The Local Personal Risk (LPR) was assessed for each building in the Groningen area for each year of the period 2018-
2027. During 2019, there is not a single building that does not meet the 10
-4
/year temporary Safety Norm level, but
some 1,500 buildings do not conform to the 10
-5
/year Safety Norm level for earthquake risk set by the Minister of
Economic Affairs and Climate Policy on advice of the Committee Meijdam (Ref. 8 to 10). However, this number
declines with time to below 100 buildings by 2024. For reference, in the Hazard, Building Damage and Risk
Assessment of November 2017 (Ref. 1), which was based on a 24 Bcm/year production scenario, this number of
buildings increased from 2,545 in 2019 to 3,228 in 2023. Maps show that by 2024, buildings exceeding the 10
-5
/year
Meijdam Norm are all located North-West of Loppersum.
The Hazard and Risk Assessment is a probabilistic assessment of the risk of individual buildings located in the
Groningen field area. The probabilistic estimate of the number of buildings where the Meijdam-Norm is exceeded,
does not directly translate into an estimate of the structural strengthening scope. The Hazard and Risk Assessment
provides a useful tool for prioritisation of building inspections.
Ultimately the structural upgrading scope will be
based on the assessment of individual buildings based on the NEN-NPR building code.
On 6/6/2018 the Minister of Economic Affairs sent a letter to Parliament informing on the progress of the measures
to end production from the Groningen field (Ref.12). In this letter, a number of additional measures are referenced
that were not yet incorporated in the ‘Basispad Kabinet as presented on 29
th
March 2018. The risk impact of a
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
6
scenario based on the maturation of these additional measures to reduce Groningen gas demand is not assessed,
but would directionally reduce the risk further as compared to the estimates provided in this report.
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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References
1
Induced Seismicity in Groningen, Assessment of Hazard, Building Damage and Risk – November 2017, NAM (Jan
van Elk and Dirk Doornhof), November 2017.
2
Letter to Parliament “Gaswinning Groningen”, 29th March 2018, Minister of Economic Affairs and Climate Policy.
3
Letter “Verwachtingenbrief aanvulling winningsplan Groningenveld 2016” to NAM, 2nd May 2018, Minister of
Economic Affairs and Climate Policy.
4
Wijziging Instemmingsbesluit Winningsplan Groningenveld, Ministerie van Economische Zaken, Directoraat-
Generaal Energie, Telecom & Mededinging, Directie Energie en Omgeving, 23 May 2017
5
Optimisation of the distribution of production over the Groningen field to reduce Seismicity, Leendert Geurtsen
and Per Valvatne, December 2017.
6
Advies Groningen-gasveld n.a.v. aardbeving Zeerijp van 8 januari 2018 and Brief aan de minister over advies
Groningen-gasveld dd. 1 februari, SodM, 1
st
February 2018.
7
Bouwstenen voor Operationele Strategie Groningenveld 2018/2019, NAM (with contributions from Gasterra
and GTS transport Services), June 2018.
8
Eerste advies Adviescommissie ‘Omgaan met risico’s van geïnduceerde aardbevingen’ 23
rd
June 2015,
9
Tweede advies Omgaan met hazard- en risicoberekeningen in het belang van handelingsperspectief voor
Groningen Adviescommissie ‘Omgaan met risico’s van geïnduceerde aardbevingen’ 29
th
October 2015,
10
Eindadvies Handelingsperspectief voor Groningen Adviescommissie ‘Omgaan met risico’s van geïnduceerde
aardbevingen’ (Commissie-Meijdam), 14
th
December 2015,