S i l i l I ti ti f th N ti l D t C t P d E i 2013Seismological Investigation of the National Data Centre Preparedness Exercise 2013Seismological Investigation of the National Data Centre Preparedness Exercise 2013Seismological Investigation of the National Data Centre Preparedness Exercise 2013g g pNicolai Gestermann Gernot Hartmann J Ole Ross and Lars CerannaNicolai Gestermann, Gernot Hartmann, J. Ole Ross , and Lars Ceranna, , ,

BGR/B4 3 Federal Institute for Geosciences and Natural Resources Hannover Germany contact: nicolai gestermann@bgr deBGR/B4.3 - Federal Institute for Geosciences and Natural Resources, Hannover, Germany, contact: nicolai.gestermann@bgr.dey g @ g

Identification of Seismic EventEpicentre Location AccuracyIntroduction Identification of Seismic EventEpicentre Location AccuracyIntroduction Identification of Seismic EventEpicentre Location AccuracyIntroductionThe Comprehensive Nuclear Test Ban Treaty (CTBT) prohibits all kinds of nuclear The scenario of a hypothetical treaty violation canThe Comprehensive Nuclear-Test-Ban Treaty (CTBT) prohibits all kinds of nuclear

l i Th ifi ti i f th CTBT i d i d t d t t t t Different epicentre determinations were comparedThe scenario of a hypothetical treaty violation can

explosion. The verification regime of the CTBT is designed to detect any treaty Different epicentre determinations were compared be verified or rejected with the investigation ofAll Stationsp g g y yviolation While the data of the International Monitoring System (IMS) is collected R f l tiwith the reference location of KNMI A Jackknife

be verified or rejected with the investigation ofi i t hi h i d ti

All Stationsviolation. While the data of the International Monitoring System (IMS) is collected,processed and technically analyzed at the International Data Centre (IDC) of the

• Reference location f KNMI

with the reference location of KNMI. A JackknifeAl ith d t ti t li ti i

seismic events which occur in space and timeprocessed and technically analyzed at the International Data Centre (IDC) of theCTBT O i ti N ti l D t C t (NDC) f th b t t id

from KNMIAlgorithm was used to estimate a realistic epi-p

relation to the NPE2013 event Seven events inCTBT-Organization, National Data Centres (NDC) of the member states provide calculated with g p

centre accuracyrelation to the NPE2013 event. Seven events ing , ( ) p

interpretation and advice to their government concerning suspicious detections phases from 14 localcentre accuracy. 2013 with a similar magnitude were selected forinterpretation and advice to their government concerning suspicious detections.Th NDC P d E i (NPE) l l f d d li ith

pstations

2013 with a similar magnitude were selected forth t l l i All t hThe NDC Preparedness Exercises (NPE) are regularly performed dealing with

R f unknown accuracy the spectral analysis. All events have aH t

p ( ) g y p gfictitious treaty violations to practice the combined analysis of CTBT verification Reference unknown accuracy

I ti A f

p ycomparable amplitude decay of the power densityHyposatfictitious treaty violations to practice the combined analysis of CTBT verification

technologies These exercises should help to evaluate the effectiveness of analysis from KNMI • Inspection Area of comparable amplitude decay of the power densityGerman NDCtechnologies. These exercises should help to evaluate the effectiveness of analysisproced res applied at NDCs and the q alit completeness and sef lness of IDC

500 km2 size would spectra which indicate that the NPE2013 eventprocedures applied at NDCs and the quality, completeness and usefulness of IDC Date 2013/09/04 be sufficient in case spectra which indicate that the NPE2013 eventhas the same so rce t pe as other si e ents ofproducts. Origin time 01:33:32.13 01:33:32.81 of an OSI has the same source type as other six events ofproducts.

The exercise trigger of NPE2013 is a combination of a tempo spatial indicationOrigin time 01:33:32.13 01:33:32.81Latitude 53 344°N 53 341°N Distances to Reference

yknown induced origin in this regionThe exercise trigger of NPE2013 is a combination of a tempo-spatial indication

i ti t t i f t d i l t d di lid t tiLatitude 53.344 N 53.341 NLongitude 6 772°E 6 752°E

Distances to Reference Location500 k 2 I ti A

known induced origin in this region.pointing to a certain waveform event and simulated radionuclide concentrations Longitude 6.772 E 6.752 E

D th 3 0 k fi d 6 9 k ± 2 2 kLocation500 km2 Inspection Areap g

generated by forward Atmospheric Transport Modelling based on a fictitious release Depth 3.0 km fixed 6.9 km ± 2.2 km 4.1 km EMSCgenerated by forward Atmospheric Transport Modelling based on a fictitious release.For the waveform event the date (4 Sept 2013) is given and the region is Magnitude 2.8 ML 2.9 ML 2.2 km GER-NDC StandardFor the waveform event the date (4 Sept. 2013) is given and the region is

i t d i h i th fi titi t t f "F i i " t th C t f thg L L

Region Groningen (Netherland) 1.4 km GER-NDC Hyposat Seismic Station IBBNcommunicated in a map showing the fictitious state of "Frisia" at the Coast of the Region Groningen (Netherland) Seismic Station IBBNp gNorth Sea in Central Europe • Distance to epicenterNorth Sea in Central Europe.Th t ti l ti b t th f d di lid id i Jackknife Algorithm

• Distance to epicenter∆ = 135 kmOnly IMS StationsThe potential connection between the waveform and radionuclide evidence remains Jackknife Algorithm

• G t b t f∆ = 135 km Only IMS Stationsp

unclear for exercise participants. The verification task was to identify the waveform • Low location• Generate subsets of • Frequencies up to unclear for exercise participants. The verification task was to identify the waveformevent and to investigate potential sources of the radionuclide findings The final

Low location accuracy due toonset times 20 Hzevent and to investigate potential sources of the radionuclide findings. The final

ti h th th fi di CTBT l t d j tif t f Oaccuracy due to missing stations at• Calculate epicentres • Similar energy contentquestion was whether the findings are CTBT relevant and justify a request for On- missing stations at local distances

Calculate epicentresof each subset (blue)

Similar energy content for wavetrain of P and SFrequency q g j y q

Site-Inspection in “Frisia”. In the following, the detection and investigation of the local distancesof each subset (blue). Crosses correspond

for wavetrain of P and Srange foranalysisSite Inspection in Frisia . In the following, the detection and investigation of the

seimic event in Frisia“ is presented • Inspection Area ofCrosses correspond to the accuracy of a

• Spectrum analysis in analysisseimic event in „Frisia is presented. Inspection Area of

1000 km2 size and1000 km2 Inspection Areato the accuracy of a single solution

the frequency range 1000 km size and the error ellipse of

1000 km Inspection Areasingle solution 2 – 10 Hzthe error ellipse of the calculated• Estimate distance

Seismic events (yellow) which occurred in thethe calculated location would failbetween median Seismic events (yellow) which occurred in the

2013 i th i th i iEpicentre Determination location would fail th flocation from year 2013 in the same region as the seismic

t i t ( d)Epicentre Determination the reference l ti (KNMI)Jackknife procedure trigger event (red).plocation (KNMI)Jackknife procedure

and Referenceand Reference location to 1 8 kmFi IMS i i t ti (bl d ) i th di t f 680 900 k Di t tlocation to 1.8 kmFive IMS seismic stations (blue and green) in the distance range of 680-900 km Distance to

R f L tiRealistic epicentreP hS h

( g ) gshowed signals of the NPE2013 seismic event Additional 40 seismic stations (red) Reference Locationp

accuracy ≈ 2 km z]

P - phases

z]

S - phasesshowed signals of the NPE2013 seismic event. Additional 40 seismic stations (red)24 3 km IMS Amplitude decay ofy

2 /Hz

2 /Hzof national networks were used to calculate the epicentre with reliable accuracy. 24.3 km IMS p y

power density

ec)2

ec)2o at o a et o s e e used to ca cu ate t e ep ce t e t e ab e accu acy

The closest station was 117 km apartpower density spectra at IBBN

m/s

m/sThe closest station was 117 km apart. spectra at IBBN

m [(

nm

S t blm [(

nm

Hypothetical Treaty Violation Scenario rum • Spectra are comparable

f ll irumThe local velocity model Hypothetical Treaty Violation Scenario pe

ctr for all seven events in

pect

rThe local velocity model ifi d ith S h ypot et ca eaty o at o Sce a o

y S

p the frequency range

y S

pwas specified with S phase

nsity 2 – 10 Hz.nsity

p pvelocities adapted to the A hypothetical scenario D

en

• Red: NPE2013 eventDenThe NPE2013 seismic trigger event occurred invelocities adapted to the A hypothetical scenario

F i i i d hid d d l wer

• Red: NPE2013 event G K i d dw

er The NPE2013 seismic trigger event occurred in

the area of the Groningen natural gas field TheVP/VS relation from the • Frisia tried to hide an underground nuclear Pow Green: Known induced

t

Powthe area of the Groningen natural gas field. TheVP/VS relation from the

W d ti di (l gexplosion within a series of intended triggered or

eventsgas production is accompanied by inducedWadati diagram (layers explosion within a series of intended triggered or gas production is accompanied by inducedi i it ith it d t 3 6 M Thi

g ( ybelow Moho) to improve induced seismic events Frequency [Hz]Frequency [Hz]seismicity with magnitudes up to 3.6 ML. Thisbelow Moho) to improve induced seismic events. Frequency [Hz]Frequency [Hz]y g p L

seismicity could be used to hide anthe epicentre accuracy.

de NPE2013 • Seismic events could be induced by massive fluidseismicity could be used to hide ant e ep ce t e accu acy

gitu

d NPE2013 seismic event

Seismic events could be induced by massive fluid i j ti t ll i th i i it f th t tunderground nuclear explosion as described in

long injection at wells in the vicinity of the test area.underground nuclear explosion as described in

th h th ti l i th i ht h dl j y• Induced seismicity in the time period before andthe hypothetical scenario on the right-hand

C l i• Induced seismicity in the time period before and yp g

side The NPE2013 radionuclide signature did ConclusionN mber of phases after a nuclear test would distract attention fromside. The NPE2013 radionuclide signature did ConclusionNumber of phases after a nuclear test would distract attention from th t tnot support a nuclear explosion source but a• Pg: 12 the test.not support a nuclear explosion source but a

t Th l i h t f th • The NPE2013 seismic event was not included in the bulletins of the IDC The eventg

• P : 41 D illi ti iti thi l i thireactor. The non-explosive character of the • The NPE2013 seismic event was not included in the bulletins of the IDC. The event Pn: 41

S 9• Drilling activities are nothing unusual in this are

pevent is also indicated by seismic discrimi- has been detected at two primary seismic station (GERES NOA) and at two auxiliary• Sg: 9

g gevent is also indicated by seismic discrimi- has been detected at two primary seismic station (GERES, NOA) and at two auxiliary i i t ti (HFS EKA)

• Sn: 30 nation analysis results. seismic stations (HFS, EKA).n

A total of 92 Distance range:nation analysis results. ( , )

latitudeA total of 92 phases

Distance range:117 – 900 km • The available detections from the seismic IMS stations lead to a epicenter accuracylatitude phases 117 – 900 km The available detections from the seismic IMS stations lead to a epicenter accuracy

f b t 24 k I f OSI th li it d 1000 2 i ti ld f il thof about 24 km. In case of an OSI the limited 1000 m2 inspection area would fail the Simplified geological cross section of• The Groningen field is part of the ptrue location

Simplified geological cross section of G i t l fi ldO t Ti

g pSouthern Permian Basin true location.Groningen natural gas fieldOnset Times Wadati DiagramSouthern Permian Basin (Rotliegend sandstone formation)

• With f d t f l l t ti d dj t d l it d l th i tWadati Diagram (Rotliegend sandstone formation).

• It i th l t t l fi ld i • With use of data from local stations and adjusted velocity models the epicenter • It is the largest natural gas field in E

j y paccuracy could be improved to less than 2 km

Europe.accuracy could be improved to less than 2 km. • The field started gas production

• Thi d t t th i l l f dditi l ti l t h i l fPn and Sn phases

g pin 1963. Production formation • This demonstrates the crucial role of additional national technical means for in 1963. Production formation depth is ≈ 3000 m

verification tasksdepth is 3000 m.

• I d d i i it t t d verification tasks.• Induced seismicity started i 1986 S i i t d • C i f t l h t i ti id tifi d th NPE2013 t th kin 1986. Seismic events occurred • Comparison of spectral characteristics identified the NPE2013 event as earthquake with magnitudes up to 3.6 ML . p p q

induced by natural gas production• A spacial correlation is observed induced by natural gas production.VP/VS = 1.74A spacial correlation is observed between national gas fields and

• Th i f ibl t t i l ti t th l ti f th i i NPE2013P S between national gas fields and

seismicity • The scenario of a possible treaty violation at the location of the seismic NPE2013 M f D t d H k 2007

seismicity p yevent could be disproved A potential OSI request is not supported by the analysis

Map from Dost and Haak 2007After NAM production plan 2007 event could be disproved. A potential OSI request is not supported by the analysis.After NAM production plan 2007