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A STUDY OF NEW ENGLAND SEISMICITY

Quarterly Earthquake Report

July - September 1998



New England
Seismic Network

    

Weston Observatory
381 Concord Road
Weston, MA 02493
Earth Resources Lab
Massachusetts Institute of Technology
42 Carleton Street
Cambridge, MA 02142



NEW ENGLAND SEISMIC NETWORK

John E. Ebel, Principal Investigator
Weston Observatory
Dept. of Geology and Geophysics
Boston College
381 Concord Road
Weston, MA 02493
Email: ebel@bcvms.bc.edu
Award # 1434-HQ-98-AG-01943
M. Nafi Toksöz, Principal Investigator
Earth Resources Lab
Dept. of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology
42 Carleton Street
Cambridge, MA 02142
Email: nafi@erl.mit.edu
Award # 1434-HQ-98-AG-01926

Prepared by Charles Doll, Jr.
Email: doll@erl.mit.edu
and Susan O'Connor
Email: dannolfo@bcvms.bc.edu
March 2000

for
United States Geological Survey
905 National Center
12201 Sunrise Valley Drive
Reston, Virginia 20192

Notice

Network operation supported by the U.S. Geological Survey (USGS), Department of the Interior, under USGS award number 1434-HQ-98-AG-01943 and award number 1434-HQ-98-AG-01926. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.

Quarterly Earthquake Report
July - September 1998


     

Table of Contents

Introduction

The New England Seismic Network (NESN) is operated collaboratively by the Weston Observatory (WES) of Boston College and the Earth Resources Lab (ERL) of the Massachusetts Institute of Technology. The mission of the NESN is to operate and maintain a regional seismic network with digital recording of seismic ground motions for the following purposes: 1) to determine the location and magnitude of earthquakes in and adjacent to New England and report felt events to public safety agencies, 2) to define the crust and upper mantle structure of the northeastern United States, 3) to derive the source parameters of New England earthquakes, and 4) to estimate the seismic hazard in the area.

This report summarizes the work of the NESN for the period July - September 1998. It includes a brief summary of the network's equipment and operation, and a short discussion of data management procedures. A list of participating personnel is given in Table 1. There were 8 earthquakes that occurred within or near the network during this reporting period. Phase information for these earthquakes is included in this report.

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Current Network Operation and Status

The New England Seismic Network currently consists of 11 broadband three-component, 4 short-period vertical, and 8 strong-motion stations. The coordinates of the stations are given in Table 2, and maps of the weak- and strong-motion networks are shown in Figures 1 and 2, respectively.

WES operates 11 stations with broadband instruments consisting of Guralp CMG-40T three-component sensors. Ground motions recorded by these sensors are digitized at 100 sps with 16-bit resolution. Additional gain-ranging provides 126 dB dynamic range. These stations are operated in dialup mode with waveform segments of suspected events transmitted in digital mode to Weston Observatory for analysis and archiving. WES is continuing to upgrade its recording stations with 4 more broadband instruments scheduled for installation in 1999. WES also maintains 8 SMA-1 strong-motion instruments in New England.

ERL at MIT currently operates 4 short-period stations, all located within 100 km of Boston. The short- period instruments have 1.0 Hz L4C vertical seismometers. Data recorded by these seismometers is transmitted continuously in analog mode to ERL and digitized (12-bit) into a PC at 50 sps. Personnel at ERL are in the process of installing a new three-component, high dynamic range instrument at Station WFM. The instrument has a CMG-40T sensor and transmits 3-channel, 24-bit data at 100 sps continuously to a central processor (Pentium PC) at ERL. Waveform windows of suspected events are extracted from the data stream, analyzed and archived. WES and ERL record some stations in analog format on helicorders to provide additional data for analysis.

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Seismicity

There were 8 earthquakes that occurred in or adjacent to the NESN during this reporting period. A summary of the location data is given in Table 3. Figure 3 shows the locations of these events. Figure 4 shows the locations of all events since the beginning of network operation in October, 1975.

Table 4 gives the station phase data and detailed hypocenter data for each event listed in Table 3. In addition to NESN data, arrival time and magnitude data sometimes are contributed for seismic stations operated by the Geological Survey of Canada (GSC), the Lamont-Doherty Cooperative Seismographic Network., and the US National Seismic Network. Final locations for this section were computed using the program HYPO78. For regional events (those too far from the NESN to obtain accurate locations and magnitudes) phase data are given for NESN stations, but the entry in Table 3 lists the hypocenter and geographic location information adopted from the authoritative network.

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Data Management

Recent event locations are available via FTP at: SEISMOEAGLE.BC.EDU. Waveform data are saved in Nanometrics, ASCII, and SEED formats and are available via SEISMOEAGLE.BC.EDU or through personal contact. Earthquake lists can be fingered at QUAKE@SEISMOEAGLE.BC.EDU. Weston Observatory maintains two web pages with information about local earthquakes: "http://www.bc.edu:80/bc_org/avp/cas/wesobs/" and "http://seismoeagle.bc.edu/". The latter page is still under contruction. Currently available on the seismoeagle web page is the full catalog of northeastern earthquake activity to 1991. This will be updated as new Northeastern U.S. Seismic Network Bulletins are produced.

The entire MIT/ERL earthquake database can be accessed through the World Wide Web using the address "http://www-erl.mit.edu/NESN/homepage.html". For extraction of waveforms (recorded by the MIT stations of the NESN through March 1995) and hypocenter data, use our database search engine. Link to "Seismic Event Server at MIT ERL (SESAME)" and then click on "Interactive query form" under the heading "Custom Materials". Alternatively, the more recent local earthquake data, recorded by the MIT stations, may be accessed by logging in to our anonymous FTP directory ("ftp sunda.mit.edu"). To be added to the list of users permitted to access this FTP directory, contact Charles Doll. The waveform files are in SAC format at both sites. Waveforms are downloaded as a Unix-compressed tar volume from our web-site and as individual, Unix-compressed, station files from our FTP site.

For more information on matters discussed in this report or general earthquake information (reports, maps, catalogs, etc.) consult our web-sites www-erl.mit.edu/NESN and www.bc.edu:80/bc_org/avp/cas/wesobs/ or contact:

Charles Doll
MIT Earth Resources Lab
42 Carleton Street
Cambridge, MA 02142


Voice: 617-253-7863 / FAX: 617-253-6385 / Email: doll@erl.mit.edu


Prof. John Ebel
Weston Observatory
381 Concord Road
Weston, MA 02493


Voice: 617-552-8319 / FAX: 617-552-8388 / Email: ebel@bcvms.bc.edu

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Explanation of Tables

Table 1: List of personnel operating the NESN

Table 2: List of Seismic and Strong Motion Stations

  1. Code = station name
  2. Lat = station latitude, degrees north
  3. Long = station longitude, degrees west
  4. Elev = station elevation in meters
  5. Location = geographic location
  6. Operator = network operator

Table 3: Earthquake Hypocenter List

  1. Date = date event occurred, Yr (year)/Mo (month)/Dy (day)
  2. Time = origin time of event, Hr (hour):Mn (minute):Sec (second)
    in UCT (Universal Coordinated Time, same as Greenwich Mean Time)
  3. Lat = event location, latitude north in degrees
  4. Long = event location, longitude west in degrees
  5. Depth = event depth in kilometers
  6. Mag = event magnitude
  7. Int = event epicentral intensity
  8. Location = event geographic location

Table 4: Earthquake detailed hypocenter and phase data list

Table Header: detailed hypocenter data

  1. Geographic location
  2. DATE = date event occurred, yr/mo/dy (year/month/day)
  3. ORIGIN = event origin time (UCT) in hours, minutes, and seconds
  4. LAT N = latitude north in degrees and minutes
  5. LONG W = longitude west in degrees and minutes
  6. DEPTH = event depth in kilometers
  7. MN = Nuttli Lg phase magnitude with amplitude divided by period
  8. MC = signal duration (coda) magnitude
    WES: 2.23 Log(FMP) + 0.12Log(Dist) - 2.36 (Rosario, 1979)
    MIT: 2.21 Log(FMP) - 1.7 (Chaplin et al., 1980)
  9. ML = local magnitude
    WES: calculated from Wood-Anderson seismograms (Ebel, 1982)
    GSC (Geological Survey of Canada): Richter Lg magnitude
  10. GAP = largest azimuthal separation, in degrees, between stations
  11. RMS = root mean square error of travel time residual in seconds
  12. ERH = standard error of epicenter in kilometers
  13. ERZ = standard error of event depth in kilometers
  14. Q = solution quality of hypocenter
    A = excellent
    B = good
    C = fair
    D = poor

Table Body: earthquake phase data

  1. STN = station name
  2. DIST = epicentral distance in kilometers
  3. AZM = azimuthal angle in degrees measured clockwise between true north and vector pointing from epicenter to station
  4. Description of onset of phase arrival
    I = impulsive
    E = emergent
  5. R = phase
    P = first P arrival
    S = first S arrival
  6. M = first motion direction of phase arrival
    U = up or compression
    D = down or dilatation
  7. K = weight of arrival
    0 = full weight (1.0)
    1 = 0.75 weight
    2 = 0.50 weight
    3 = 0.25 weight
    4 = no weight (0.0)
  8. HRMN = hour and minute of phase arrival
  9. SEC = second of phase arrival
  10. TCAL = calculated travel time of phase in seconds
  11. RES = travel time residual (error) of phase arrival
  12. WT = weight of phase used in hypocentral solution
  13. AMX = peak-to-peak ground motion, in millimicrons, of the maximum envelope amplitude of vertical-component signal, corrected for system response
  14. PRX = period in seconds of the signal from which amplitude was measured
  15. XMAG = Nuttli magnitude recorded at station
  16. FMP = signal duration (coda), in seconds, measured from first P arrival
  17. FMAG = coda magnitude recorded at station

Table 5: Microearthquakes and other non-locatable events

  1. Date = date event occurred, Yr (year)/Mo (month)/Dy (day)
  2. Sta = nearest station recording event
  3. Arrival Time = phase arrival time, Hr (hour):Mn (minute):Sec (second)

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TABLE 1



     

WESTON OBSERVATORY PERSONNEL

Name Network Position voice phone email address
John E. Ebel Principal Investigator 617-552-8319 ebel@bcvms.bc.edu
Alan Kafka Research Seismologist 617-552-8300 kafka@bcvms.bc.edu
Susan O'Connor Seismic Analyst 617-552-8337 dannolfo@bcvms.bc.edu
Edward Johnson Project Engineer 617-552-8332 johnson@bcvms.bc.edu
Patricia Tassia Administrative Secretary 617-552-8311 tassia@bcvms.bc.edu
W. Richard Ott, S.J. Assistant to the Director 617-552-8335 ottwi@mail1.bc.edu
Weston Observatory
617-552-8300
617-552-8388 (FAX)



     

MIT/ERL PERSONNEL

Name

Network Position voice phone email address
M. Nafi Toksöz Principal Investigator 617-253-7852 nafi@erl.mit.edu
Charles Doll Research Seismologist 617-253-7863 doll@erl.mit.edu
Charles Doll Seismic Analyst 617-253-6290 doll@erl.mit.edu
Sara Brydges Administrator 617-253-7797 sara@erl.mit.edu
Earth Resources Lab
617-253-8027
617-253-6385 (FAX)



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TABLE 2



     

SEISMIC STATIONS OF THE NEW ENGLAND SEISMIC NETWORK

Code Lat Long Elev (m) Location Operator
BCX 42.3350 -71.1705 61.0 Chestnut Hill, MA WES
BRY 41.9178 -71.5388 380.0 Smithfield, RI WES
DNH 43.1225 -70.8948 24.0 Durham, NH MIT
DXB 42.0610 -70.6992 8.0 Duxbury, MA MIT
GLO 42.6403 -70.7272 15.2 Gloucester, MA MIT
HNH 43.7050 -72.2860 180.0 Hanover, NH WES
MIM 45.2436 -69.0403 140.0 Milo, ME WES
NH1 43.5473 -71.5743 402.0 Sanbornton, NH WES
QUA2 42.2789 -72.3525 168.0 Belchertown, MA WES
TRY 42.7311 -73.6669 131.0 Troy, NY WES
VT1 44.3317 -72.7536 410.0 Waterbury, VT WES
WES 42.3850 -71.3220 60.0 Weston, MA WES
WFM 42.6106 -71.4906 87.5 Westford, MA MIT
WVL 44.5648 -69.6575 85.0 Waterville, ME WES
YLE 41.3100 -72.9269 9.14 New Haven, CT WES

     

STRONG MOTION STATIONS OF THE NEW ENGLAND SEISMIC NETWORK

Code Lat Long Location Operator
SM1 44.90 -67.25 Dennysville, ME WES
SM2 44.49 -73.10 Essex Junction, VT WES
SM3 41.45 -71.33 Newport, RI WES
SM4 42.38 -71.32 Weston, MA WES
SM5 42.66 -71.30 Lowell, MA WES
SM6 42.30 -71.34 Natick, MA WES
SM7 42.39 -71.54 Hudson, MA WES
SM8 44.48 -69.61 North Vassalboro, ME WES

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TABLE 3



     

EARTHQUAKE HYPOCENTER LIST
NEW ENGLAND AND ADJACENT REGIONS
July - September 1998

Date
Yr/Mo/Dy
Time
Hr:Mn:Sec
Lat Long Depth
(km)
Mag Int Location
1998/07/07 09:41:42.44 43.2115 -71.6683 .17 2.1
NH, W of Concord
1998/07/09 01:52:15.30 44.6763 -73.6460 .17 2.3
NY, W of Plattsburgh
1998/07/15 07:08:05.13 47.0000 -66.6463 5.0 4.3
NB, Miramichi Region
1998/07/30 08:57:24.22 46.2171 -74.7200 34.96 4.0
PQ, Ste Agathe-des Monts
1998/08/24 19:27:35.71 44.0405 -75.8023 1.56 2.9
NY, Near Watertown
1998/09/05 05:19:56.12 44.3475 -68.6405 5.0 2.3
ME, Near Blue Hill Falls
1998/09/16 07:49:10.63 44.9258 -67.2036 5.0 2.6
ME, Approx 30 km NE of Machias < /td>
1998/09/25 19:52:52.48 41.471 -80.483 5.0 5.2
OH,30 km N of Sharon (USGS location )

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TABLE 4

EARTHQUAKE PHASE DATA LIST
NEW ENGLAND AND ADJACENT REGIONS
July - September 1998

 HUGHES AND LUETGERT NH
 98JUL07 NH, W OF CONCORD
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980707  941 42.44 43-12.69  71-40.10   0.17  2.1 2.2      87  0.37  1.8  5.8 C
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  NH1  38.1  12 IP 0  941 49.23   6.79   6.57  0.22 1.52 303 .16  2.3
                 S 0  941 53.92  11.48  11.70 -0.22 1.52
  DNH  63.6  99  P 0  941 53.20  10.76  10.91 -0.15 1.46               98  2.4
                 S 4  941 59.20  16.76  19.41 -2.65 0.00
  WFM  68.3 168  P 0  941 54.10  11.66  11.70 -0.05 1.44               59  2.0
                 S 4  941 60.80  18.36  20.83 -2.49 0.00
  HNH  74.2 318 IPU1  941 54.62  12.18  12.69 -0.54 0.99  60 .11  1.9
                 S 4  941 63.71  21.27  22.58 -1.37 0.00
  WES  96.1 163 EPU0  941 58.75  16.31  16.26  0.04 1.36  51 .15  2.0
                 S 4  941 70.06  27.62  28.94 -1.33 0.00
  BCX 105.5 157 EPU2  941 60.91  18.47  17.79  0.68 0.56  65 .21  2.1
                 S 4  941 73.70  31.26  31.66 -0.40 0.00
 QUA2 117.8 208 EPU2  941 61.52  19.08  19.78 -0.73 0.52  50 .14  2.1
                 S 4  941 75.58  33.14  35.21 -2.13 0.00
  BRY 144.1 176 EPU3  941 66.69  24.25  23.94  0.31 0.30  39 .17  2.1
                 S 4  941 83.05  40.61  42.61 -2.00 0.00
  DXB 150.5 148  P 4  941 69.30  26.86  24.93  1.93 0.00               49  2.1
                 S 4  941 84.50  42.06  44.38 -2.32 0.00
  VT1 152.1 325  S 0  941 87.92  45.48  44.80  0.65 1.04
  TRY 171.5 252 EP 3  941 70.62  28.18  28.18  0.00 0.28  37 .15  2.2
                 S 4  941 89.55  47.11  50.16 -3.05 0.00
  WVL 217.5  48 EPU4  941 78.89  36.45  34.17  2.27 0.00  32 .29  2.2
 NORTHERN NY AND ADIRONDACKS
 98JUL09 NY, W OF PLATTSBURG
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980709  152 15.30 44-40.58  73-38.76   0.17  2.3         298  0.13  1.5  1.3 B
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  VT1  80.6 118 EPC1  152 27.79  12.49  12.71 -0.24 1.19 181 .14  2.4
                 S 1  152 38.04  22.74  22.62  0.09 1.20
  HNH 153.2 135 EPC1  152 38.93  23.63  23.70 -0.10 1.02  31 .15  2.1
                 S 1  152 57.49  42.19  42.19 -0.05 1.02
  NH1 208.0 127 EPC0  152 47.42  32.12  31.97  0.16 1.17  40 .16  2.4
                 S 0  152 72.29  56.99  56.90  0.09 1.17
  TRY 216.2 180 EPC3  152 50.26  34.96  32.98  1.99 0.00  35 .17  2.3
                 S 2  152 74.15  58.85  58.70  0.16 0.57
 QUA2 286.1 159 EP 1  152 56.86  41.56  41.62 -0.08 0.68   9 .12  2.2
                 S 4  152 91.89  76.59  74.08  2.46 0.00
 NORTHWEST MAINE CRUSTAL STRUCTURE
 98JUL15 NB, MIRAMICHI REGION
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980715  7 8  5.13 47- 0.00  66-38.78   5.00  4.3         133  0.33  2.1 **** C
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  LMN 190.6 132  P 0  7 8 35.07  29.94  29.99 -0.05 1.79
  GSQ 215.6 351  P 0  7 8 38.86  33.73  33.08  0.63 1.40
                 S 0  7 8  1.99  -3.14  58.89-62.05 0.00
  A21 242.7 289  P 0  7 8 41.98  36.85  36.43  0.42 1.47
                 S 0  7 8  9.88   4.75  64.84-60.09 0.00
  A11 271.0 276  P 0  7 8 44.77  39.64  39.91 -0.29 1.38
  A61 271.7 286  P 0  7 8 44.82  39.69  40.01 -0.33 1.36
                 S 0  7 8 15.78  10.65  71.21-60.58 0.00
  CNQ 277.1 337  P 0  7 8 45.70  40.57  40.67 -0.14 1.36
                 S 0  7 8 18.44  13.31  72.40-59.15 0.00
  ICQ 284.2 351  P 0  7 8 46.68  41.55  41.55 -0.01 1.32
                 S 0  7 8 22.38  17.25  73.96-56.73 0.00
  LMQ 285.0 282  P 0  7 8 47.00  41.87  41.64  0.16 1.32
  A54 289.9 280  P 0  7 8 47.57  42.44  42.25  0.12 1.30
  SMQ 358.4 359  P 0  7 8 55.51  50.38  50.71 -0.39 0.92
  WVL 361.3 221  S 0  7 9 47.47 102.34  90.89 11.43 0.00
  MNQ 422.4 338  P 0  7 9  2.93  57.80  58.62 -0.82 0.39
  DPQ 469.4 266  P 0  7 9  9.14  64.01  64.41 -0.41 0.39
                 S 0  7 9 58.15 113.02 114.66 -1.64 0.00
  MOQ 471.8 247  P 0  7 9 10.26  65.13  64.70  0.28 0.39
                 S 0  7 9 57.37 112.24 115.17 -3.19 0.00
 LBNH 513.6 233 EP 0  7 9 15.05  69.92  69.87 -0.02 0.18
  NH1 544.6 225 EPC0  7 9 19.32  74.19  73.70  0.48 0.02 667 .28  4.3
  VT1 560.6 238 EPC0  7 9 39.10  93.97  75.67 18.28 0.00
  MNT 562.7 253  P 0  7 9 20.74  75.61  75.93 -0.33 0.00
                 S 0  7 9 77.76 132.63 135.16 -2.53 0.00
  HNH 573.6 230 EP 0  7 9 22.21  77.08  77.28 -0.23 0.00 593 .28  4.3
  TRQ 612.2 262  P 0  7 9 26.19  81.06  82.04 -0.99 0.00
  BCX 630.4 215 EPC0  7 9 29.34  84.21  84.28 -0.08 0.00 765 .41  4.3
  WES 632.8 216 EPC0  7 9 29.36  84.23  84.58 -0.37 0.00 661 .38  4.3
  HRV 632.8 218 EP 0  7 9 29.72  84.59  84.59  0.00 0.00
 QUA2 693.2 221 EPC0  7 9 58.35 113.22  92.04 21.14 0.00 568 .40  4.3
  GRQ 704.8 266  P 0  7 9 37.61  92.48  93.47 -0.99 0.00
  EEO 949.6 268  P 0  7 9 65.65 120.52 123.69 -3.18 0.00
 NORTHWEST MAINE CRUSTAL STRUCTURE
 98JUL30 PQ, STE AGATHE-DES-MONTS
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980730  857 24.22 46-13.03  74-43.20  34.96  4.0         125  0.56  2.7  4.4 D
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  VT1 260.2 144 EPC1  858  0.82  36.60  35.81  0.78 1.20
                 S 4  858 34.48  70.26  63.74  6.49 0.00
  DAQ 327.8  54  P 0  858  8.54  44.32  44.15  0.01 1.46
                 S 1  858 43.70  79.48  78.59  0.61 1.08
  EEO 338.1 278  P 1  858 10.22  46.00  45.43  0.58 1.06
  HNH 338.8 145 EPC2  858 11.50  47.28  45.51  1.74 0.401144 .42  3.9
                 S 4  858 56.32  92.10  81.01 11.04 0.00
  A54 356.5  67  P 0  858 11.98  47.76  47.71  0.00 1.38
                 S 1  858 50.17  85.95  84.92  0.93 0.98
  A11 364.2  72  P 0  858 12.89  48.67  48.65  0.02 1.36
                 S 1  858 50.24  86.02  86.60 -0.59 1.00
  LMQ 366.0  66  P 0  858 13.10  48.88  48.88 -0.06 1.35
                 S 0  858 50.80  86.58  87.00 -0.54 1.32
  A16 385.5  69  P 0  858 15.61  51.39  51.29  0.11 1.30
  NH1 387.0 140 IPC2  858 17.21  52.99  51.47  1.53 0.47 884 .35  4.0
                 S 4  858 68.44 104.22  91.61 12.61 0.00
  A61 388.5  65  P 0  858 15.86  51.64  51.65 -0.01 1.29
                 S 1  858 55.50  91.28  91.93 -0.66 0.94
  TRY 396.3 168 EPC1  858 16.32  52.10  52.62 -0.51 0.941713 .79  4.1
                 S 4  858 67.68 103.46  93.66  9.81 0.00
  A64 408.6  64  P 0  858 18.20  53.98  54.13 -0.17 1.23
                 S 0  858 60.68  96.46  96.35  0.08 1.23
  A21 416.8  67  P 0  858 19.41  55.19  55.14  0.05 1.21
                 S 1  858 61.51  97.29  98.15 -0.86 0.86
  WVL 437.8 115 EPC4  858 18.95  54.73  57.74 -3.02 0.00 845 .44  4.0
                 S 4  858 82.28 118.06 102.78 15.26 0.00
  MIM 455.4 104  PC0  858 24.20  59.98  59.91  0.05 1.10
                 S 4  858 87.92 123.70 106.64 17.03 0.00
  WFM 476.2 147 EP 3  858 30.40  66.18  62.48  3.69 0.00
                 S 4  858 91.30 127.08 111.22 15.85 0.00
 QUA2 476.8 157 EPC0  858 27.35  63.13  62.55  0.56 1.03 385 .43  3.8
                 S 4  858 92.11 127.89 111.34 16.50 0.00
  EFO 503.1 226  P 1  858 29.25  65.03  65.80 -0.76 0.70
                 S 1  858 80.48 116.26 117.12 -0.86 0.69
  WES 504.9 148 EPC1  858 29.53  65.31  66.02 -0.71 0.70 561 .45  3.9
                 S 4  858 99.89 135.67 117.51 18.15 0.00
  BCX 516.0 147 EPC4  858 48.16  83.94  67.40 16.55 0.00
  DXB 563.0 145 EP 4  858 54.10  89.88  73.19 16.69 0.00
  MNQ 651.2  43  P 0  858 47.75  83.53  84.09 -0.55 0.54
  LMN 769.1  93  P 1  858 62.05  97.83  98.64 -0.80 0.16
 NORTHERN NY AND ADIRONDACKS
 98AUG24 NY, NEAR WATERTOWN
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980824 1927 35.71 44- 2.43  75-48.14   1.56  2.9         193  0.62  5.5  8.3 D
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  TRQ 261.6  22  P 3 1928 13.26  37.55  38.43 -0.88 0.49
                 S 4 1928 47.35  71.64  68.41  3.23 0.00
  HNH 285.0  98 EPC3 1928 15.58  39.87  41.33 -1.49 0.34  52 .16  2.8
                 S 0 1928 49.91  74.20  73.56  0.58 1.85
  GRQ 285.2 359  P 4 1928 19.78  44.07  41.35  2.71 0.00
  MOQ 314.7  63  P 0 1928 20.57  44.86  45.00 -0.28 1.68
                 S 1 1928 55.92  80.21  80.10 -0.14 1.26
 QUA2 341.9 125 EP 0 1928 23.96  48.25  48.36 -0.14 1.49  91 .31  2.9
                 S 2 1928 60.28  84.57  86.07 -1.56 0.46
  NH1 344.6  99 EP 1 1928 25.09  49.38  48.69  0.69 1.07  93 .20  3.1
                 S 2 1928 63.33  87.62  86.67  0.95 0.67
  DPQ 377.0  39  P 0 1928 28.33  52.62  52.69 -0.07 1.24
                 S 3 1928 68.55  92.84  93.79 -0.95 0.29
  EEO 386.5 318  P 0 1928 29.94  54.23  53.85  0.37 1.16
                 S 4 1928 68.24  92.53  95.86 -3.33 0.00
  WES 408.0 117  S 4 1928 82.22 106.51 100.58  5.90 0.00  91 .55  2.9
 SOUTHEAST MAINE CRUSTAL MODEL
 98SEP05 ME, NEAR BLUE HILL FALLS
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980905  519 56.12 44-20.85  68-38.43   5.00  2.3 2.7     164  0.52  3.9  6.2 D
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  WVL  84.2 284 EP 0  520 10.36  14.24  13.62  0.60 1.79  67 .13  2.0
                 S 0  520 19.79  23.67  24.25 -0.60 1.75
  MIM 104.5 342 IP 0  520 12.70  16.58  16.84 -0.28 1.71  60 .14  2.1 127  2.7
                 S 0  520 26.49  30.37  29.97  0.36 1.71
  NH1 251.9 249 EPC1  520 36.00  39.88  36.87  3.01 0.10  31 .18  2.4
                 S 4  520 65.77  69.65  65.62  4.03 0.00
  HNH 301.0 256 EPC4  520 46.17  50.05  42.92  7.10 0.00  20 .20  2.3
                 S 4  520 81.57  85.45  76.39  9.00 0.00
  MOQ 305.4 291  P 0  520 39.71  43.59  43.46 -0.02 0.94
  WES 307.8 225 EPC0  520 39.91  43.79  43.76  0.02 0.93  13 .15  2.3
                 S 4  520 74.20  78.08  77.90  0.16 0.00
  LMN 345.0  61  P 0  520 43.85  47.73  48.36 -0.63 0.77
                 S 4  520 79.95  83.83  86.08 -2.25 0.00
 QUA2 378.9 233  P 4  520 42.11  45.99  52.54 -6.58 0.00  25 .32  2.5
                 S 4  520 60.18  64.06  93.52-29.51 0.00
  A21 381.8 348  P 0  520 48.73  52.61  52.90 -0.29 0.65
                 S 4  520 89.72  93.60  94.16 -0.56 0.00
  DPQ 414.5 309  P 0  520 53.42  57.30  56.93  0.36 0.52
                 S 4  520 94.37  98.25 101.34 -3.09 0.00
  GSQ 521.0  13  P 0  520 66.45  70.33  70.09  0.23 0.11
 SOUTHEAST MAINE CRUSTAL MODEL
 98SEP16 ME, APPROX 30 KM NE OF MACHIAS
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980916  749 10.63 44-55.55  67-12.22   5.00  2.6 3.0     168  0.66  3.9  4.4 D
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  MIM 148.8 284 IPC0  749 34.24  23.61  23.88 -0.29 2.97  82 .14  2.5 132  2.8
                 S 0  749 53.18  42.55  42.50  0.02 2.97
  WVL 200.1 257 EPC3  749 43.14  32.51  30.47  2.03 0.50  64 .17  2.5 167  3.0
                 S 3  749 60.01  49.38  54.23 -4.87 0.00
  LMN 214.1  61  P 0  749 42.58  31.95  32.20 -0.25 2.49
  A11 346.3 318  P 1  749 59.90  49.27  48.52  0.74 1.12
  A21 363.4 328  P 1  749 61.81  51.18  50.62  0.56 1.02
  A54 374.9 319  P 0  749 63.09  52.46  52.04  0.36 1.30
  A61 379.7 324  P 0  749 63.42  52.79  52.64  0.14 1.26
  NH1 381.5 246 EPC2  750  2.35  51.72  52.86 -1.14 0.61  34 .16  2.9 144  3.1
                 S 4  750 53.65 103.02  94.09  8.93 0.00
  MOQ 399.9 276  P 0  750  5.58  54.95  55.13 -0.32 1.11
                 S 3  750 46.64  96.01  98.13 -2.37 0.21
  HNH 427.6 252 EPC3  750 11.39  60.76  58.56  2.17 0.16  25 .21  2.8
                 S 4  750 68.71 118.08 104.23 13.80 0.00
  WES 435.8 230 EPC2  750 11.19  60.56  59.57  0.98 0.41  17 .25  2.5
                 S 4  750 50.94 100.31 106.03 -5.74 0.00
  GSQ 443.5   1  P 1  750 11.90  61.27  60.51  0.75 0.58
                 S 0  750 58.18 107.55 107.71 -0.18 0.79
  VT1 445.6 261 EPC4  749 22.34  11.71  60.77-49.08 0.00
                 S 4  749 49.05  38.42 108.18-69.79 0.00
  DAQ 458.9 317  P 1  749 72.32  61.69  62.41 -0.88 0.50
  DPQ 475.2 294  P 0  750 14.54  63.91  64.43 -0.52 0.55
                 S 3  750 63.24 112.61 114.68 -2.07 0.12
  CNQ 491.0 352  P 1  749 76.51  65.88  66.38 -0.53 0.33
 QUA2 509.3 235  S 4  751 69.90 179.27 122.17 57.04 0.00
  MNQ 634.1 349  P 0  749 94.47  83.84  84.05 -0.21 0.00
 SOUTH & COASTAL NEW ENGLAND, CHIBURIS, 1979
 98SEP25 OH, OHIO-PENNSYLVANIA BORDER (NESN LOCATION POOR)
  DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
 980925 1952 25.78 40-33.17  82-54.98   5.00  5.4 4.7     326  0.18 74.9 **** D
  STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
  EEO 744.3  25  P 4 1954 11.88 106.10  98.03  8.07 0.00
                 S 4 1954 69.30 163.52 174.49-10.97 0.00
  TRY 808.2  73 IPU0 1954 11.87 106.09 105.92  0.17 2.78
  YLE 846.0  84 EP 4 1954 17.12 111.34 110.58  0.76 0.00              668  4.4
  TRQ 924.9  47  P 0 1954 26.08 120.30 120.33 -0.03 1.10
                 S 4 1954 98.26 192.48 214.18-21.70 0.00
  VT1 936.1  63 EPD4 1954  2.34  96.56 121.71-25.17 0.00
  MNT 936.3  54  P 0 1954 27.39 121.61 121.74 -0.13 0.92
  HNH 946.6  68 IPD0 1954 28.62 122.84 123.00 -0.19 0.76
  BRY 966.3  81 IPD0 1954 30.85 125.07 125.44 -0.37 0.41
  WES 989.2  78 IPD0 1954 33.46 127.68 128.27 -0.60 0.032659 .44  5.4   0  4.9
  NH1 995.5  70 IPD0 1954 34.94 129.16 129.04  0.12 0.00
  BCX1002.0  79 IPU0 1954 35.24 129.46 129.85 -0.39 0.004283 .66  5.4   0  4.6
  DPQ1064.8  50  P 0 1954 42.29 136.51 137.60 -1.09 0.00
  WVL1175.4  68 IPU0 1954 56.52 150.74 151.25 -0.52 0.00              855  4.7
  A111263.6  54  P 0 1954 67.36 161.58 162.14 -0.57 0.00

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TABLE 5



     

MICROEARTHQUAKES AND OTHER NON-LOCATABLE EVENTS

Date
Yr/Mo/Dy
Sta Arrival Time
Hr:Mn:Sec
None recorded this quarter


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NESN Station Map

Figure 1: Map of stations of the New England Seismic Network (NESN) in operation during period July - September, 1998. Also included are the US National Seismic Network stations operating in New England during this period.

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NESN Strong-Motion Station Map

Figure 2: Map of strong-motion stations of the New England Seismic Network (NESN) in operation during period July - September, 1998.

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NESN Quarterly Seismicity Map

Figure 3: Earthquake epicenters located by the NESN during period July - September, 1998.

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NESN Cumulative Seismicity Map

Figure 4: Seismicity for period October, 1975 - September, 1998.

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Acknowledgments

We would like to thank the Undergraduate Research Opportunities Program (UROP) of MIT for its support to the network. Our map database has been developed in-house using ARCINFO and in part basemap data provided by ESRI, Inc. (Arcdata Online), USGS GTOPO30 Elevation Data, and TIGER/Line '94, '95, and '97 (US Census Bureau) spatial data.

References

Chaplin, M.P., Taylor, S.R., and Toksöz, M.N. (1980), A coda length magnitude scale for New England, Earthquake Notes, 51, 15-22.

Ebel, J.E. (1982), ML measurements for northeastern United States earthquakes, Bull. Seism. Soc. Am., 72, 1367-1378.

Rosario, M. (1979), A coda duration magnitude scale for the New England Seismic Network, Master's Thesis, Boston College, 82 pp.

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