MICHAEL FORNASIERO DAEE – RPI 4/1/2009 Seismic Sleuthing

Background October 4 th, 2006 North Korea announces plans to test a nuclear weapon. October 9 th, the People’s Republic of China notifies the US that a test is imminent. 20 minutes after a warning was received seismographs of the USArray pickup signals of a seismic event to the west. More data is becoming available from IRIS (Incorporated Research Institutions for Seismology)

Task Analyze the data to find the epicenter of the seismic event.  The epicenter location could be beneficial for satellite surveillance. Determine if the event could have been natural or from a nuclear test.  Could the event be from an earthquake, mine collapse, or nuclear blast.

Seismic Data The following represents actual data collected from seismographs near the epicenter of the event. Some of interpretation may already be performed for you to aid in understanding of the seismograph charts.

Location 1 Station: MDJ - Mudanjiang, Heilongjiang Province, China Network: IC - New China Digital Seismograph Network Lat: Lon: Elev: Event Name: _ spyder The 1 st vertical line on each plot will be the P-Wave and the 2 nd vertical line will mark the S-Wave time. From this chart you determine that the difference in travel times between the P and S Waves is 40 seconds. Refer to the enclosed wave travel time chart to determine distance from station. Epicenter Distance (km)__________ 375

Location 2 Station: INCN - Inchon, Republic of Korea Network: IU - Global Seismograph Network (GSN - IRIS/USGS) Lat: Lon: Elev: Event Name: _ spyder Data from this station suggests a difference in travel times between the P and S Waves of approximately 60 seconds. Epicenter Distance (km)__________ 500

Location 3 Station: MAJO - Matsushiro, Japan Network: IU - Global Seismograph Network (GSN - IRIS/USGS) Lat: Lon: Elev: Event Name: _ spyder A colleague has contacted you about their recording. He has determined that the P-Wave was detected at 1:37:27 UTC and the S-Wave at 1:39:17 UTC. What is his distance from the epicenter? Epicenter Distance (km)____________ 950

More Questions How long will it take the P-Wave to travel from the epicenter to East Greenbush if the distance is around 10,000km between locations? P-Wave Travel Time_____________ If the P-wave was felt at 10:48:00 UTC when did the seismic event occur? Time of Event___________ 00:12:50 10:35:10

Plotting the Event Point 1 – Latitude________ Longitude________ Point 2- Latitude_________ Longitude________ 41.7° N 127.3° E 129.1° E 41.3° N From the help you gave to your colleague in Japan you find out that the epicenter is East of 128° Longitude. With this information you now know the source of the seismic disturbance.

Determining the Cause of the Disturbance Now that we know the location of the seismic event we can start to figure out what caused the disturbance. We need to look at;  The seismic history of the area  The form of the seismograph signal  The location itself and its surroundings

Seismic History of the Site The epicenter is marked with a star. The scale represents levels of seismic activity in the area. (0-low,5-high) Looking at the scale and the star’s location is this an area of active seismic activity?

Form of the Signal A – Pakistan B – India C – Soviet Union D – North Korea Red – Nuclear Tests Blue – Natural Earthquakes Image Courtesy:

The Location There is always some error in measurement, this shows up as a Radius of Uncertainty. Where do you think this error comes from? USGS Predicted: 41°16’ N 129°6’E Actual: 41°29’N 129°8’E

Satellite View of Location

Gov’t Surveillance Photo (OCT7,2006)

Results of Investigation The device’s estimated yield was less than 1kt. It is likely that the test failed to achieve an expected yield of 4kt.  Yet it is of note that North Korea participated in a Pakistani nuclear test in 1998, this could have boosted confidence in North Korean scientists to perform a test at less than full yield. ISIS estimates North Korea is capable of producing 4-13 nuclear weapons, while at reduced yields could produce 7-35 weapons.

North Korea’s Capabilities Tactical and Theatre Ballistic Missiles;  Nodong missile: 1,000kg nuclear weapon to 1,500km (covers all of Japan)  Taepo Dong I: 750kg nuclear weapon to 2,300km  Taepo Dong II: 300kg nuclear weapon to 6,000km (reach Alaska) North Korea has also supplied many missile and weapon components to Iran and Pakistan.

Sources Johnston, W. R. “North Korea’s First Nuclear Test” OCT21,2006 USGS Earthquake Hazards Program “Quake Details October 9 01:35:28 UTC” Broadband Seismic Data Collection Center “October 8 th, 2006 Magnitude 4.2MB Event From an Alleged Nuclear Test in North Korea” Site Image Ammon, C.J. and Thorne Lay “USArray Records the 9 October 2006 North Korean Nuclear Test” OCT23, 2006 Submitted to EOS Walter, Bill “Sleuthing Seismic Signals” S&TR March 2009 “Earth Quake Events 2006: IRIS” 3/25/2009