V w ESD RECORD COW ^D^^3X AMPLITUDE SCATTER 11-2 ESD-TR Copy Ho» NOVEMBER 2, MASSACHUSETTS INSTITUTE of TECHNOLOGY

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1 11-2 ESD-TR cc u* H I Ofw m ESTl ESTt Call No. l -- ^^T^ ESD RECORD COW RETURN TO SCIENTIFIC & TECHNICAL INFLATION DIVISION 0 ll>. fukdhtg m Copy Ho» * L A S A AMPLITUDE SCATTER NOVEMBER 2, 1966 REPORT No. LL-2 Prepared for LINCOLN LABORATORIES MASSACHUSETTS INSTITUTE of TECHNOLOGY V w EARTH SCIENCES, A TEIEDYNE COMPANY ^D^^3X

2 LL-2 59 L A S A AMPLITUDE SCATTER NOVEMBER 2, 1966 REPORT No. LL-2 Prepared for LINCOLN LABORATORIES MASSACHUSETTS INSTITUTE of TECHNOLOGY Purchase Order BB r 2U6 PBIME CONTRACT AP 19(628)-5167 w EARTH SCIENCES, A TEIEDYNE COMPANY

3 TABLE OF CONTENTS Page No FOREWARD ABSTRACT INTRODUCTION 1 PROCEDURE 1 1. LASA-UBSO 1 2. LASA-TFSO 2 CONCLUSIONS 3 APPENDIX A

4 FOREWARD The work documented n ths report s part of a study of ampltude anomales observed at the Large Aperture Sesmc Array (LASA) n Montana. Ths report was wrtten by Do E. Frankowsk Assstance was provded by A. L. Kurtz, R c D. Merley and Po Ao Santago. The project drector was P W. Broome o The work was performed by the Appled Research Secton, Earth Scences, a Teledyne Company, 316 Montgomery Street, Alexandra, Vrgna, under Lncoln Laboratores Contract No. BB-246. Accepted for the Ar Force Frankln C. Hudson Chef, Lncoln Laboratory Offce

5 ABSTRACT Sesmc sgnal ampltude scatter s shown by demon- straton to be characterstc of present sesmc arrays rather than a unque characterstc of LASA»

6 INTRODUCTION It has been observed that there s consderable scatter n sgnal ampltudes recorded at LASA for a typcal event. It s the purpose of ths paper to demonstrate that the ampltude scatter at LASA s not a unque characterstc of ths array but rather a common property of sesmc arrays, PROCEDURE LASA ampltudes were compared to Unta Basn Sesmologcal Observatory (UBSO) and Tonto Forest Sesmologcal Observatory (TFSO) ampltudes. 1. LASA-UBSO 1.1 Snce LASA s much larger than UBSO, the center nstrument plus the 2-rng, 3-rng, and 4-rng nstruments from a LASA subarray were used to smulate an array smlar n sze and confguraton to UBSO (Fgure 1). Ths was done for the AO, B2, and F4 subarrays. 1.2 The amount of LASA ampltude data avalable was lmted due to the choce of nstruments used n ths study. (No 16 mm flm was avalable) LASA ampltudes for three Mexcan and two Kurle Islands events were obtaned from a computer program» UBSO ampltudes for two Mexcan and two Kurle Islands events were obtaned from analysts observa

7 LASA B2 Subarray (Center 2-,3-,4- Rngs Only) 1 LASA F4 Subarray (Center 2-,3-,&4- Rngs Only) LASA AO Subarray (Center 2-,3-,4-Rng Only) Unta Basn Sesmologcal Observatory (UBSO) 0 1 Klometers Fgure 1

8 tons of 16 mm flm., Table 1 shows these data and a measure of the ampltude scatter at each array. 1.3 Fgures 2 and 3 show the normalzed ampltudes* plotted for each staton for the two source regons. It s seen from ths plot that the normalzed ampltude scatter at each LASA staton s no greater than the scatter observed at UBSO, even though the LASA scatter s greater over sngle events as shown n Table LASA-TFSO 2.1 An array smlar to LASA n sze and confguraton can be smulated at TFSO f the TFSO extended array s ncluded. 2 2 TFSO sgnal ampltudes for seven Aleutan Islands events were computed from analysts' observatons. (The events used for each subarray were not the same group because the two arrays were not n operaton at the same tme.) Tables 2A and 2B show these data and a measure of the ampltude scatter at each array. 2.3 Fgure 4 shows the normalzed ampltudes plotted for each staton. It s seen from *The procedure used to normalze ampltudes s descrbed n Appendx A.

9 UBSO AMPLITUDES (MILLIMICRONS) KURILE KURILE MEXICO MEXICO STATION #1 #2 #3 #4 Zl Z Z Z Z Z Z LASA AO AMPLITUDES (MILLIMICRONS) KURILE KURILE MEXICO MEXICO MEXICO STATION #1 #2 #3 #4 #5 AO AO AO AO AO < AO No Data No Data 15 AO < Q 16 Z Z AO AO O Z Z MEAN STD. DEV AO PC AO STD. DEV. MEAN AO MEAN STD. DEV STD. DEV. MEAN LASA B2 AMPLITUDES (MILLIMICRONS) KURILE KURILE MEXICO MEXICO MEXICO STATION #1 #2 #3 #4 #5 B B B B B B B B B B B B B LASA F4 AMPLITUDES (MILLIMICRONS) KURILE KURILE MEXICO MEXICO MEXICO STATION #1 #2 #3 #4 #5 F F F F F F F F F F F F F MEAN MEAN STD. DEV STD. DEV STD. DEV. MEAN STD. DEV MEAN Table 1

10 t.o ~+- } tm EVENT ^ s'^*... s ^"^\.-»-* EVENT tf± r 1 1 F4I F4 Subarray Normalzed Ampltudes for Kurle Events "^S^ EVENT # ^ ^ y,/v ^>^ ' V r / r EVENT #2^ / * «** V B2I B2 Subarray Normalzed Ampltudes for Kurle Events r.o EVENT #1 "~ \ \^ > <» w ^' ^ m <v f..v EVENT #Z ^ ^>^» A0I AO Subarray Normalzed Ampltudes for Kurle Events EVEN! ' #1 " "">! / /~~ EVENT L, #2 r-^ Zl Z2 Z3 Z4 Z3 Z6 Z7 Z8 Z9 ZI0 ÜBS0 Array Normalzed Ampltudes for Kurle Events Fgure 2

11 e.o F4I0 El SI F4 Subarray Normalzed Ampltudes for Mexcan Events B2I B2 Subarray Normalzed Ampltudes for Mexcan Events 2.0 r- EVENT #3 L\ 1 I * EVENT #5 k! \ \ N ^~ f > v N > A- Ty n / \ 9 e.7 6 -=^ 'S A0I AO Subarray Normalzed Ampltudes for Mexcan Events EVENT # "'S ^^> <^/r ^ "^*^_ fy \ tvüwt =ffj Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 ZIO UBSO Normalzed Ampltudes for Mexcan Events MEX] CCO E\ 'ENTS Fgure 3

12 TFSO AMPLITUDES (MILLIMICRONS) STD. DEV. EVENT EVENT EVENT EVENT EVENT EVENT EVENT OF NORM. STATION #1 #2 #3 #4 #5 #6 #7 AMPLITUDE Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z SG-AZ JR-AZ LG-AZ GE-AZ SN-AZ HR-AZ WO-AZ NL2AZ Z MEAN STD. DEV STD. DEV. MEAN Table 2A

13 LASA AMPLITUDES (MILLIMICRONS) STD. DEV. EVENT EVENT EVENT EVENT EVENT EVENT EVENT OF NORM. STATION #1 #2 #3 #4 #5 #6 #7 AMPLITUDE Bl B B B Cl C C C Dl D D D El E E E Fl F F F AO MEAN STD. DEV STD. DEV. MEAN Table 2B

14 > > * > > > l I ( ' 7 7 f ' 1! ' r * 7 f F r 7. f ILL.11 k» E! T k 1 k 1 k 1 ' 7 > Bl B2 B3 B4 Cl C2 C3 C4 Dl D2 03 D4 El E2 E3 E4 Fl F2 F3 F4 A0 k LASA Normalzed Ampltudes for Seven Aleutan Events > > [»»» < I \ t : > 4 < : ' 1! I 1 <U,1 1! t \ a 1 > «\ t 1.7 \ '} -\ 7 ;f T 1 7 > <\ f I* c.4 T t,1 I <> 3 ZI7 ZIO ZI5 Z23 Z5 Z20 Z29 ZI3 Z2 Z60 Z25 Z7I Z64 Z6I Z68 Z69 Z73 Z66 Z63 Z70 SG JR L6 GE SN HR WO NL2 ZI6 TFSO Normalzed Ampltudes for Seven Aleutan Events Fgure 4

15 ths plot that LASA ampltude scatter s no greater than TFSO ampltude scatter, CONCLUSIONS Sesmc sgnal ampltude scatter s not a unque characterstc of LASA but s a common property of sesmc arrays

16 APPENDIX A Normalzed ampltudes are used to reduce events of dfferent average sgnal levels to a common scale» The normalzed ampltude Y for Staton I and Event J s defned I / J as "I,J X I,J GEOMEAN. where X s the observed ampltude and geomean s the geo- metrc mean of the observed ampltudes for event J and Geomean = Log ) Log X J L N I,JJ 1=1 N where N s the number of observed ampltudes for event J

17 UNCLASSIFIED Securty Classfcaton DOCUMENT CONTROL DATA - R&D (Securty classfcaton of ttle, body of abstract and Indexng annotaton must be entered when the overall report la classfed) 1. ORIGINATING ACTIVITY (Corporate author) Earth Scences, a Teledyne Company, under P.O. No. BB-246 to Lncoln Laboratory, M.I.T. 3. REPORT TITLE 2a. REPORT SECURITY CLASSIFICATION Unclassfed 2b. GROUP None LASA Ampltude Scatter 1 4. DESCRIPTIVE NOTES (Type of report and nclusve datea) Progress Report 5. AUTHOR(S) (Last name, frst name, ntal) Frankowsk, D. E. 6. REPORT DATE 2 November a. TOTAL NO. OF PAGES 16 7b. NO. OF REFS None 8a. CONTRACT OR GRANT NO. AF 19(628)-5167 b. PROJECT NO. ARPA Order 512 c. d. 10. AVAILABILITY/LIMITATION NOTICES 9a. ORIGINATOR'S REPORT NUMBER(S) Report No. LL-2 9b. OTHER REPORT NO(S) (Any other numbers that may be assgned ths report) ESD-TR Dstrbuton of ths document s unlmted. 11. SUPPLEMENTARY NOTES None 12. SPONSORING MILITARY ACTIVITY Advanced Research Projects Agency, Department of Defense 13. ABSTRACT Sesmc sgnal ampltude scatter s shown by demonstraton to be characterstc of present sesmc arrays rather than a unque characterstc of LASA. 14. KEY WORDS LASA sesmology* ampltude scatter - UNCLASSIFIED Securty Classfcaton.

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