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A STUDY OF NEW ENGLAND SEISMICITY

Quarterly Earthquake Report
April-June, 2004

New England
Seismic Network



Weston Observatory

381 Concord Road

Weston, MA 02493





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@bc.edu

Award # 04HQAG0020

Prepared by Anastasia Macherides Moulis

Email: macherid@bc.edu

July 1, 2004

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 04HQAG0020. The views and conclusions contained in this document are those of the authors andshould not be interpreted as necessarily representing the official policies,either expressed or implied, of the U.S. Government.

Quarterly Earthquake Report

April-June, 2004

Table of Contents

Introduction

The New England Seismic Network (NESN) is operated by the Weston Observatory (WES) of Boston College. 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 ofthe 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 April-June, 2004. 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 2 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 of Weston Observatory of Boston College currently consists of 11 broadband three-component and 8 analog 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. The 11 stations consist 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 also maintains 8 SMA-1 strong-motion instruments in New England.

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Seismicity

There were 2 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. Accordingly, the epicenter is plotted on the maps using the entry from Table 3.

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Data Management

Recent event locations are available at http://aki.bc.edu/cgi-bin/NESN/recent_events.pl. Waveform data are saved in Nanometrics, ASCII, and SEED formats and are available by contacting, Anastasia Macherides Moulis, via email. Earthquake lists can be found at www.bc.edu/research/westonobservatory/northeast/eqcatalogs/. Currently available on the Weston Observatory web page is the full catalog of northeastern U.S. earthquake activity to the present time. This will be updated as new Northeastern U.S. Seismic Network Quarterly Earthquake Reports are produced.

For more information on matters discussed in this report or general earthquake information (reports, maps, catalogs, etc.) consult our web site www.bc.edu/westonobservatory or contact:

Anastasia Macherides Moulis

Weston Observatory

381 Concord Road

Weston, MA 02493

Voice: 617-552-8325 / FAX: 617-552-8388 / Email: anastasia.macherides.1@bc.edu

Dina Smith

Weston Observatory

381 Concord Road

Weston, MA 02493

Voice: 617-552-8335 / FAX: 617-552-8388 / Email: dina.smith.1@bc.edu

Prof. John Ebel

Weston Observatory

381 Concord Road

Weston, MA 02493

Voice: 617-552-8319 / FAX: 617-552-8388 / Email: ebel@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

  • Code = station name
  • Lat = station latitude, degrees north
  • Long = station longitude, degrees west
  • Elev = station elevation in meters
  • Location = geographic location
  • Operator = network operator
  • Table 3: Earthquake Hypocenter List

  • D ate = date event occurred, Yr (year)/Mo (month)/Dy (day)
  • Time = origin time of event, Hr (hour):Mn (minute):Sec (second)

    in UCT (Universal Coordinated Time, same as Greenwich Mean Time)
  • Lat = event location, latitude north in degrees
  • Long = event location, longitude west in degrees
  • Depth = event depth in kilometers
  • Mag = event magnitude
  • Int = event epicentral intensity
  • Location = event geographic location
  • Table 4: Earthquake detailed hypocenter and phase data list

    Table Header: detailed hypocenter data

  • Geographic location
  • DATE = date event occurred, yr/mo/dy (year/month/day)
  • ORIGIN = event origin time (UCT) in hours, minutes, and seconds
  • LAT N = latitude north in degrees and minutes
  • LONG W = longitude west in degrees and minutes
  • DEPTH = event depth in kilometers
  • MN = Nuttli Lg phase magnitude with amplitude divided by period
  • 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)
  • ML = local magnitude
    WES: calculated from Wood-Anderson seismograms (Ebel, 1982)
    GSC (Geological Survey of Canada): Richter Lg magnitude
  • GAP = largest azimuthal se paration, in degrees, between stations
  • RMS = root mean square error of travel time residual in seconds
  • ERH = standard error of epicenter in kilometers
  • ERZ = standard error of event depth in kilometers
  • Q = solution quality of hypocenter
    A = excellent
    B = good
    C = fair
    D = poor
  • Table Body: earthquake phase data

  • STN = station name
  • DIST = epicentral distance in kilometers
  • AZM = azimuthal angle in degrees measured clockwise between true north and vector pointing from epicenter to station
  • Description of onset of phase arrival
    I = impulsive
    E = emergent
  • R = phase
    P = first P arrival
    S = first S arrival
  • M = first motion direction of phase arr ival
    U = up or compression
    D = down or dilatation
  • 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)
  • HRMN = hour and minute of phase arriva l
  • SEC = second of phase arrival
  • TCAL = calculated travel time of phase in seconds
  • RES = travel time residual (error) of phase arrival
  • WT = weight of phase used in hypocentral solution
  • AMX = peak-to-peak ground motion, in millimicrons, of the maximum envelope amplitude of vertical-component signal, corrected for system response
  • PRX = period in seconds of the signal from which amplitude was measured
  • XMAG = Nuttli magnitude recorded at station
  • FMP = sign al duration (coda), in seconds, measured from first P arrival
  • FMAG = coda magnitude recorded at station
  • Table 5: Microearthquakes and other non-locatable events

  • Date = date event occurred, Yr (year)/Mo (month)/Dy (day)
  • Sta = neares t station recording event
  • Arrival Time = phase arrival time, Hr (hour):Mn (minute):Sec (second)

  • Return to Table of Contents

    TABLE 1



    WESTON OBSERVATORY PERSONNEL

    Name Network Position voice phone email address
    John E. Ebel Principal Investigator 617-552-8319 ebel@bc.edu
    Alan Kafka Research Seismologist 617-552-8300 kafka@bc.edu
    Anastasia Macherides Moulis Seismic Analyst 617-552-8325 macherid@bc.edu
    Edward Johnson Project Engineer 617-552-8332 johnson@bc.edu
    Dina Smith Assistant to the Director 617-552-8335 dina.smith.1@bc.edu
    Weston Observatory
    617-552-8300

    617-552-8388 (FAX)



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    TABLE 2

    
              

    SEISMIC STATIONS OF THE NEW ENGLAND SEISMIC NETWORK

    WES 43.7050 -72.3525 Belchertown, MATroy, NY WES UMM WES 42.3850 WES YLE PQI 46.6710
    Code Lat Long Elev (m) Location Operator
    BCX 42.3350 -71.1705 61.0 Chestnut Hill, MA WES
    BRYW 41.9178 -71.5388 380.0 Smithfield, RI WES
    FFD 43.4702 -71.6533 131.0 Franklin Falls Dam, NH
    HNH -72.2860 180.0 Hanover, NH WES
    QUA2 42.2789 168.0 WES
    TRY * 42.7311 -73.6669 131.0
    44.7100 -67.4583 35.0 Machias, ME WES
    VT1 44.3317 -72.7536 410.0 Waterbury, VT WES
    -71.3220 60.0 Weston, MA WES
    WVL 44.5648 -69.6575 85.0 Waterville, ME
    41.3100 -72.9269 10.0 New Haven, CT WES
    -68.0168 175.0 Presque Isle, ME WES

    * = not in operation during this quarter

    
              

    STRONG MOTION STATIONS OF THE NEW ENGLAND SEISMIC NETWORK

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


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    TABLE 3



    
              

    NEW ENGLAND AND ADJACENT REGIONS

    April-June, 2004


    Date

    M/D/Y
    Time (UTC)

    Hr:Mn:Sec
    Lat Long Depth

    (km)
    Mag Int Location
    05/24/2004 08:58:28.88 43.5055 -70.9663 2.80 1.9
    NH-ME BORDER, 15KM NE OF FARMINGTON, NH
    06/22/2004 10:17:52.95 45.175 -69.1236 9.47 2.0
    ME, 9.65KM (6MI) NE OF DOVER-FOXCROFT
    * indicates Mc rather than Mn.

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    TABLE 4

    EARTHQUAKE PHASE DATA LIST
    NEW ENGLAND AND ADJACENT REGIONS
    April-June, 2004

    B4524A.XX
     SOUTHEAST MAINE CRUSTAL MODEL
     04MAY24 NH-ME BORDER, 15KM (24.14MI) NE OF FARMINGTON, NH
      DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
      40524  858 28.88 43-30.33  70-57.98   2.80  1.9  .0     145   .24  1.2  1.9 B
      STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
      HNH 108.8 282 EP 0  858 46.64  17.76  17.61   .12 1.33
                    ES 0  858 60.12  31.24  31.35  -.16 1.32
      HRV 121.0 204 EP 1  858 48.85  19.97  19.55   .39  .87
                    ES 0  858 63.54  34.66  34.80  -.20 1.28
      WES 127.9 193 EP 1  858 49.74  20.86  20.63   .22  .93
                    ES 1  858 65.42  36.54  36.73  -.21  .94
      BCX 131.1 187 EP 1  858 50.36  21.48  21.15   .30  .91  18 .14  1.7
                    ES 1  858 66.12  37.24  37.64  -.46  .80
      WVL 154.4  42 EP 1  858 53.48  24.60  24.84  -.25  .87  25 .14  2.0
                    ES 4  858 71.25  42.37  44.22 -1.86  .00
     QUA2 177.2 220 EP 1  858 57.02  28.14  27.88   .23  .82
                    ES 0  858 78.45  49.57  49.62  -.10 1.12
      BRY 182.5 195 ES 1  858 80.01  51.13  50.79   .23  .81
      UMM 311.2  65 EP 4  859 18.09  49.21  44.42  4.78  .00   4 .12  2.0
                    ES 4  859 53.35  84.47  79.06  5.39  .00
     B4622A.XX
     SOUTHEAST MAINE CRUSTAL MODEL
    ME, 9.65 KM (6 MI) NE OF DOVER-FOXCROFT
      DATE     ORIGIN    LAT N    LONG W   DEPTH   MN  MC  ML GAP   RMS  ERH  ERZ Q
      40622 1017 52.95 45-13.05  69- 7.42   9.47  2.0  .0      96   .73  4.3  7.4 D
      STN  DIST AZM  RMK HRMN   SEC   TOBS   TCAL   RES   WT AMX PRX XMAG FMP FMAG
      WVL  87.6 209 EP 0 1018  6.17  13.22  14.19  -.98 3.00  52 .17  1.9
                    ES 2 1018 18.38  25.43  25.25   .16 1.57
      UMM 142.9 113 EP 0 1018 16.64  23.69  22.96   .72 2.70  29 .16  2.0
                    ES 2 1018 34.40  41.45  40.86   .57 1.36
      GGN 181.2  94  P 4 1018 20.90  27.95  27.69   .25  .00
                     S 4 1018 42.58  49.63  49.28   .33  .00
      PQI 183.0  28 EP 0 1018 20.43  27.48  27.91  -.46 2.49  26 .15  2.1
                    ES 2 1018 41.23  48.28  49.67 -1.45 1.05
      A11 239.9 340  P 1 1018 28.45  35.50  34.93   .56 1.56
                     S 1 1018 55.38  62.43  62.18   .24 1.58
      MOQ 245.8 272  P 3 1018 30.60  37.65  35.66  1.85  .32
                     S 3 1018 56.51  63.56  63.47  -.16  .52
      A54 268.0 338  P 3 1018 31.68  38.73  38.41   .26  .48
                     S 3 1018 61.03  68.08  68.36  -.39  .48
      A21 279.7 351  P 3 1018 33.59  40.64  39.85   .78  .44
                     S 3 1018 63.88  70.93  70.94  -.03  .46
      A64 296.0 349  P 3 1018 35.61  42.66  41.86   .78  .42
                     S 3 1018 67.57  74.62  74.52   .07  .43
      HNH 302.4 236 EP 4 1018 45.73  52.78  42.65 10.10  .00
                    ES 4 1018 81.33  88.38  75.92 12.40  .00
      DPQ 326.9 300  P 3 1018 39.47  46.52  45.67   .85  .37
                     S 3 1018 74.97  82.02  81.29   .73  .37
      LMN 344.8  78  P 3 1018 40.47  47.52  47.88  -.42  .35
                     S 3 1018 75.97  83.02  85.23 -2.32  .08
      WES 361.1 209 EP 4 1018 35.93  42.98  49.89 -6.92  .00
                    ES 4 1018 87.17  94.22  88.81  5.39  .00
      GSQ 438.5  20  P 4 1018 52.55  59.60  59.45   .14  .00
                     S 4 1018 95.56 102.61 105.82 -3.23  .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 period.


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    NESN Station Map

    Figure 1: Map of stations of the New England Seismic Network (NESN) in operation during the period of this report. Also included are other Northeast U.S. and Canadian seismic stations in operation 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 the period of this report.

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    NESN Quarterly Seismicity Map

    Figure 3: Earthquake epicenters located by the NESN during the period of this report.

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    NESN Cumulative Seismicity Map

    Figure 4: Seismicity for period October, 1975 - June, 2004.

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    Acknowledgments

    Our map database has been developedin-house using ArcView and in part basemap data provided byESRI, 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 lengthmagnitude scale for New England, Earthquake Notes, 51, 15-22.

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

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

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