MICHAEL FORNASIERODAEE – RPI

4/1/2009

Seismic Sleuthing

Background

October 4th, 2006 North Korea announces plans to test a nuclear weapon.

October 9th, 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 NetworkLat: 44.62 Lon: 129.59 Elev: 270.00 Event Name: 20061009_013527.0.spyder

The 1st vertical line on each plot will be the P-Wave and the 2nd 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: 37.48 Lon: 126.62 Elev: 80.00 Event Name: 20061009_013527.0.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: 36.55 Lon: 138.20 Elev: 405.00 Event Name: 20061009_013527.0.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 – PakistanB – IndiaC – Soviet UnionD – North Korea

Red – Nuclear TestsBlue – Natural Earthquakes

Image Courtesy: https://str.llnl.gov/Mar09/walter.html

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 <www.johnstonarchive.net>

USGS Earthquake Hazards Program “Quake Details October 9 01:35:28 UTC” <www.earthquake.usgs.gov/…/ustqab/>

Broadband Seismic Data Collection Center “October 8th, 2006 Magnitude 4.2MB Event From an Alleged Nuclear Test in North Korea” <www.eqinfo.ucsd.edu/…/index.php>

Site Image <www.nrdc.org/media/docs/061013b.jpg>

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 <www.iris.edu/news/special_2006.htm>