Since 1984, we have issued quarterly bulletins for all of Washington and Oregon. These include catalogs of earthquakes and blasts located in Washington and Oregon, providing up-to-date coverage of seismic and volcanic activity. Appendix 1 contains quarterly bulletins covering 1998.
The PNSN is currently in the process of upgrading operations, including extensive changes to data recording, exchange, and processing systems. Upgrades include enhancement of the emergency information distribution system, installation of seismic sensors that can accurately capture the full range of earthquake amplitudes and frequencies, implementation of a data recording system that fully supports multi-component data, and near-real-time data exchange with neighboring networks.
The USGS/NOAA CREST (Consolidated Reporting of EarthquakeS and Tsunamis) project is designed to improve NOAA's ability to assess the likelihood of a tsunami and issue timely warnings in the event of a west coast subduction earthquake. CREST calls for upgrades to regional networks to enable them to provide very rapid and reliable information to the Alaska and Pacific Tsunami Warning Centers. While recent PNSN station upgrades have been in urban areas, our updating effort is fully compatible with the USGS/NOAA CREST project. The EARTHWORM data reporting system, already in use at the PNSN, has been selected for use by CREST. At the end of 1998 we had three CREST-compatible stations (real-time, broadband, and strong-motion) installed and two more will be installed early in the next year.
Near the end of the year we received some additional funding to support the development of a lahar notification system using the conventional seismic network to supplement the development by CVO for using Acoustic Flow Monitors even mudflow events at Mount Rainier generate seismic signals at PNSN seismographs on and near the mountain. The EARTHWORM realtime monitoring system has the capability to easily add modules for special purposes. Near the end of 1998 we developed and tested an algorithm using a Realtime Seismic Amplitude Monitor (RSAM) scheme to both detect and provide a crude location for any type of large seismic event source. This algorithm will be installed and tested in the EARTHWORM system during the next year.
In May of 1996 the US Geological Survey (USGS) funded the Pacific Northwest Seismograph Network (PNSN) to begin a pilot project of modern strong-motion instrumentation in the Puget Sound urban area. Six sites were installed earlier under USGS special contract 1434-HQ-96-GR-02714. Six additional instruments were purchased by the USGS, and five of them were installed during 1998. Plans exist for installation of another 6-8 instruments, in cooperation with the Bonneville Power Administration (BPA). Table 1C gives locations, instrumentation, and telemetry methods used for each of the current strong-motion stations. Several of the strong-motion sites also have broad-band three-component sensors.
RACE is an earthquake notification system for emergency managers and others who need very rapid pager-based notification of earthquake activity. The RACE system is based on the CUBE system developed at Caltech for the Southern California Seismic Network. The RACE system is operating in prototype mode at five emergency management agencies in Washington and Oregon. An article on the development and future potential of rapid notification systems appeared in the December, 1997 issue of Washington Geology Vol. 25, No. 4, pp. 33-36. The article is entitled "Rapid Earthquake Notification in the Pacific Northwest" by A. Qamar, S.D. Malone, and R.S. Ludwin
The PNSN has implemented a earthquake notification distribution system using the NOAA National Weather Service "National Weather Warning System" (NWWS). After an alert-level (M >= 3) earthquake has been reviewed by a seismologist, a special message is sent via Internet to the Seattle NOAA facility and broadcast on their NWWS satellite system.
As of January 1, 1998, the PNSN switched routine data processing from the SUNWORM system to a hybrid EARTHWORM/SUNWORM system. PNSN programmer Pete Lombard assisted with EARTHWORM development. Specific recent accomplishments include:
The PNSN now maintains a comprehensive set of EARTHWORM documentation on the CNSS (Council for the National Seismic System) Web-site: "http://www.cnss.org/EWAB"
One of the PIs (SDM) of this contract was elected Chairman of the Council of the National Seismic System (CNSS) in 1997. His duties as chairman are considered related to this cooperative agreement and thus are partially supported by this agreement. During this year the CNSS Chairman managed a set of master CNSS WEB pages, including national meeting summaries and EarthWorm Advisory Board pages, as well as other routine CNSS business. He also coordinated a review and documentation of the "Inventory of the National Seismic System" (http://www.cnss.org/NETS) and provided material and editorial review of the USGS assessment report to Congress.
At the end of 1998, the PNSN was digitally recording 198 channels of real-time seismic data in triggered mode and receding a possible additional 42 channels via dial-up or Internet request for individual special events. Stations available include a total of 137 short-period analog stations, 15 broad-band and 11 strong-motion stations. The operation of 106 sites (some with multiple components) were supported under this contract, JOA 1434-HQ-98-AG-01937 The majority of stations consist of a single, short-period vertical, component which is telemetered continuously in analog form to the UW. In addition, JOA 1434-HQ-98-AG-01937 supports operation of the 11 strong motion stations and 8 of the broad-band stations, plus horizontal seismometers with Wood-Anderson-response at station SEA on the campus of the University of Washington. The supported stations cover much of western Washington and Oregon, including the volcanos of the central Cascades.
Additional stations funded by other contracts are also used in event locations. The locations of all stations operating at the end of 1998 are given in Tables 1A (short-period), 1B (broad-band), and 1C (strong motion) and shown in Fig. 1. Quarterly reports provide additional details of station operation. Quarterly reports from January 1, 1998 through December, 1998 are included as Appendix 1.
Aside from station outages, normal maintenance includes a visit to each site at least once every two years to replace batteries and do preventive maintenance. In addition seismometers must be replaced every 4-6 years. More than 30 radio telemetry relay sites are also maintained independently of the seismograph stations.
Table 1A lists short-period stations with continuous telemetry to the PNSN lab which were operated by the PNSN at the end of the reporting period. Table 1B lists broad-band stations in the Pacific Northwest, and Table 1C lists strong-motion, three component stations. The first column in Tables 1A and 1B gives the 3-letter station designator. Column 2 designates the funding agency; operations of stations marked by a % symbol were fully supported by USGS joint operating agreement 1434-HQ-98-AG-01937 Stations designated # were installed or are maintained by the USGS, but are telemetered to the PNSN lab. Stations from the Northern California network, received over internet, are marked "C". Data from some of the broad-band stations operated under other support are archived at the PNSN. Remaining columns give station north latitude and west longitude (in degrees, minutes and seconds), station elevation in km, and comments indicating landmarks for which stations were named.
TABLE 1A Short-period Stations operating during the fourth quarter 1998 STA F LAT LONG EL NAME ASR % 46 09 09.9 121 36 01.6 1.357 Mt. Adams - Stagman Ridge AUG % 45 44 10.0 121 40 50.0 0.865 Augspurger Mtn BBO % 42 53 12.6 122 40 46.6 1.671 Butler Butte, Oregon BHW % 47 50 12.6 122 01 55.8 0.198 Bald Hill BLN % 48 00 26.5 122 58 18.6 0.585 Blyn Mt. BOW % 46 28 30.0 123 13 41.0 0.870 Boistfort Mt. BPO % 44 39 06.9 121 41 19.2 1.957 Bald Peter, Oregon BRV + 46 29 07.2 119 59 28.2 0.920 Black Rock Valley BVW + 46 48 39.6 119 52 59.4 0.670 Beverly CBS + 47 48 17.4 120 02 30.0 1.067 Chelan Butte, South CDF % 46 07 01.4 122 02 42.1 0.756 Cedar Flats CMW % 48 25 25.3 122 07 08.4 1.190 Cultus Mtns. CPW % 46 58 25.8 123 08 10.8 0.792 Capitol Peak CRF + 46 49 30.0 119 23 13.2 0.189 Corfu DBO 43 07 09.0 123 14 34.0 0.984 Dodson Butte, Oregon DPW + 47 52 14.3 118 12 10.2 0.892 Davenport DY2 + 47 59 06.6 119 46 16.8 0.890 Dyer Hill 2 EDM # 46 11 50.4 122 09 00.0 1.609 East Dome, Mt. St. Helens ELK % 46 18 20.0 122 20 27.0 1.270 Elk Rock ELL + 46 54 34.8 120 33 58.8 0.789 Ellensburg EPH + 47 21 22.8 119 35 45.6 0.661 Ephrata ET3 + 46 34 38.4 118 56 15.0 0.286 Eltopia (replaces ET2) ETW + 47 36 15.6 120 19 56.4 1.477 Entiat FBO % 44 18 35.6 122 34 40.2 1.080 Farmers Butte, Oregon FL2 % 46 11 47.0 122 21 01.0 1.378 Flat Top 2 FMW % 46 56 29.6 121 40 11.3 1.859 Mt. Fremont GBL + 46 35 54.0 119 27 35.4 0.330 Gable Mountain GHW % 47 02 30.0 122 16 21.0 0.268 Garrison Hill GL2 + 45 57 35.0 120 49 22.5 1.000 New Goldendale GLK % 46 33 27.6 121 36 34.3 1.305 Glacier Lake GMO % 44 26 20.8 120 57 22.3 1.689 Grizzly Mountain, Oregon GMW % 47 32 52.5 122 47 10.8 0.506 Gold Mt. GSM % 47 12 11.4 121 47 40.2 1.305 Grass Mt. GUL % 45 55 27.0 121 35 44.0 1.189 Guler Mt. HAM % 42 04 08.3 121 58 16.0 1.999 Hamaker Mt., Oregon HBO % 43 50 39.5 122 19 11.9 1.615 Huckleberry Mt., Oregon HDW % 47 38 54.6 123 03 15.2 1.006 Hoodsport HOG % 42 14 32.7 121 42 20.5 1.887 Hogback Mtn., Oregon HSO % 43 31 33.0 123 05 24.0 1.020 Harness Mountain, Oregon HSR % 46 10 28.0 122 10 46.0 1.720 South Ridge, Mt. St. Helens HTW % 47 48 14.2 121 46 03.5 0.833 Haystack Lookout JBO + 45 27 41.7 119 50 13.3 0.645 Jordan Butte, Oregon JCW % 48 11 42.7 121 55 31.1 0.792 Jim Creek JUN % 46 08 50.0 122 09 04.4 1.049 June Lake KEB C 42 52 20.0 124 20 03.0 0.818 CAL-NET KMO % 45 38 07.8 123 29 22.2 0.975 Kings Mt., Oregon KOS % 46 27 46.7 122 11 41.3 0.610 Kosmos KSX C 41 49 51.0 123 52 33.0 CAL-NET KTR C 41 54 31.2 123 22 35.4 1.378 CAL-NET LAB % 42 16 03.3 122 03 48.7 1.774 Little Aspen Butte, Oregon LAM C 41 36 35.2 122 37 32.1 1.769 CAL-NET LCW % 46 40 14.4 122 42 02.8 0.396 Lucas Creek LMW % 46 40 04.8 122 17 28.8 1.195 Ladd Mt. LNO + 45 52 18.6 118 17 06.6 0.771 Lincton Mt., Oregon LO2 % 46 45 00.0 121 48 36.0 0.853 Longmire LOC + 46 43 01.2 119 25 51.0 0.210 Locke Island LON % 46 45 00.0 121 48 36.0 0.853 Longmire (BB,LONLZ) LVP % 46 04 06.0 122 24 30.0 1.170 Lakeview Peak MBW % 48 47 02.4 121 53 58.8 1.676 Mt. Baker MCW % 48 40 46.8 122 49 56.4 0.693 Mt. Constitution MDW + 46 36 47.4 119 45 39.6 0.330 Midway MEW % 47 12 07.0 122 38 45.0 0.097 McNeil Island MJ2 + 46 33 27.0 119 21 32.4 0.146 May Junction 2 MOX + 46 34 38.4 120 17 53.4 0.501 Moxie City MPO % 44 30 17.4 123 33 00.6 1.249 Mary's Peak, Oregon MTM % 46 01 31.8 122 12 42.0 1.121 Mt. Mitchell NAC + 46 43 59.4 120 49 25.2 0.728 Naches NCO % 43 42 14.4 121 08 18.0 1.908 Newberry Crater, Oregon NEL + 48 04 12.6 120 20 24.6 1.500 Nelson Butte NLO % 46 05 21.9 123 27 01.8 0.826 Nicolai Mt., Oregon OBC % 48 02 07.1 124 04 39.0 0.938 Olympics - Bonidu Creek OBH % 47 19 34.5 123 51 57.0 0.383 Olympics - Burnt Hill OCP % 48 17 53.5 124 37 30.0 0.487 Olympics - Cheeka Peak OD2 + 47 23 15.6 118 42 34.8 0.553 Odessa site 2 OFR % 47 56 00.0 124 23 41.0 0.152 Olympics - Forest Resource Center OHW % 48 19 24.0 122 31 54.6 0.054 Oak Harbor ONR % 46 52 37.5 123 46 16.5 0.257 Olympics - North River OOW % 47 44 03.6 124 11 10.2 0.561 Octopus West OSD % 47 48 59.2 123 42 13.7 2.008 Olympics - Snow Dome OSR % 47 30 20.3 123 57 42.0 0.815 Olympics Salmon Ridge OT3 + 46 40 08.4 119 13 58.8 0.322 New Othello OTR % 48 05 00.0 124 20 39.0 0.712 Olympics - Tyee Ridge PAT + 45 52 55.2 119 45 08.4 0.262 Paterson PGO % 45 27 42.6 122 27 11.5 0.253 Gresham, Oregon PGW % 47 49 18.8 122 35 57.7 0.122 Port Gamble PRO + 46 12 45.6 119 41 08.4 0.553 Prosser RC1 + 46 56 42.6 119 26 39.6 0.485 Royal City RCM % 46 50 08.9 121 43 54.4 3.085 Mt. Rainier, Camp Muir RCS % 46 52 15.6 121 43 52.0 2.877 Mt. Rainier, Camp Schurman RER % 46 49 09.2 121 50 27.3 1.756 Mt. Rainier, Emerald Ridge RMW % 47 27 35.0 121 48 19.2 1.024 Rattlesnake Mt. (West) RNO % 43 54 58.9 123 43 25.5 0.850 Roman Nose, Oregon RPW % 48 26 54.0 121 30 49.0 0.850 Rockport RSW + 46 23 40.2 119 35 28.8 1.045 Rattlesnake Mt. (East) RVC % 46 56 34.5 121 58 17.3 1.000 Mt. Rainier - Voight Creek RVN % 47 01 38.6 121 20 11.9 1.885 Raven Roost (former NEHRP temp) RVW % 46 08 53.2 122 44 32.1 0.460 Rose Valley SAW + 47 42 06.0 119 24 01.8 0.701 St. Andrews SEP # 46 12 00.7 122 11 28.1 2.116 September lobe, Mt. St. Helens Dome SHW % 46 11 37.1 122 14 06.5 1.425 Mt. St. Helens SLF % 47 45 32.0 120 31 40.0 1.750 Sugar Loaf SMW % 47 19 10.7 123 20 35.4 0.877 South Mtn. SND % 46 12 45.0 122 11 09.0 1.800 St. Helens Microphone, unrectified SOS % 46 14 38.5 122 08 12.0 1.270 Source of Smith Creek SSO % 44 51 21.6 122 27 37.8 1.242 Sweet Springs, Oregon STD % 46 14 16.0 122 13 21.9 1.268 Studebaker Ridge STW % 48 09 03.1 123 40 11.1 0.308 Striped Peak TBM + 47 10 12.0 120 35 52.8 1.006 Table Mt. TCO % 44 06 27.6 121 36 02.1 1.975 Three Creek Meadows, Oregon TDH % 45 17 23.4 121 47 25.2 1.541 Tom,Dick,Harry Mt., Oregon TDL % 46 21 03.0 122 12 57.0 1.400 Tradedollar Lake TKO % 45 22 16.7 123 27 14.0 1.024 Trask Mtn, Oregon TRW + 46 17 32.0 120 32 31.0 0.723 Toppenish Ridge TWW + 47 08 17.4 120 52 06.0 1.027 Teanaway VBE % 45 03 37.2 121 35 12.6 1.544 Beaver Butte, Oregon VCR % 44 58 58.2 120 59 17.4 1.015 Criterion Ridge, Oregon VFP % 45 19 05.0 121 27 54.3 1.716 Flag Point, Oregon VG2 % 45 09 20.0 122 16 15.0 0.823 Goat Mt., Oregon VGB + 45 30 56.4 120 46 39.0 0.729 Gordon Butte, Oregon VIP % 44 30 29.4 120 37 07.8 1.731 Ingram Pt., Oregon VLL % 45 27 48.0 121 40 45.0 1.195 Laurance Lk., Oregon VLM % 45 32 18.6 122 02 21.0 1.150 Little Larch, Oregon VRC % 42 19 47.2 122 13 34.9 1.682 Rainbow Creek, Oregon VSP % 42 20 30.0 121 57 00.0 1.539 Spence Mtn, Oregon VT2 + 46 58 02.4 119 59 57.0 1.270 Vantage2 VTH % 45 10 52.2 120 33 40.8 0.773 The Trough, Oregon WA2 + 46 45 19.2 119 33 56.4 0.244 Wahluke Slope WAT + 47 41 55.2 119 57 14.4 0.821 Waterville WG4 + 46 01 49.2 118 51 21.0 0.511 Wallula Gap WIB % 46 20 34.8 123 52 30.6 0.503 Willapa Bay WIW + 46 25 45.6 119 17 15.6 0.128 Wooded Island WPO % 45 34 24.0 122 47 22.4 0.334 West Portland, Oregon WPW % 46 41 55.7 121 32 10.1 1.280 White Pass WRD + 46 58 12.0 119 08 41.4 0.375 Warden WRW % 47 51 26.0 120 52 52.0 1.189 Wenatchee Ridge YA2 + 46 31 36.0 120 31 48.0 0.652 Yakima YEL # 46 12 35.0 122 11 16.0 1.750 Yellow Rock, Mt. St. Helens
Table 1B lists broad-band, three-component stations operating in Washington and Oregon that provide data to the PNSN. Stations are operated by the University of Washington (UW), Oregon State University (OSU), the University of Oregon (UO), or the US Geological Survey US National Seismograph Network (USGS-USNSN).
TABLE 1B Broad-band three-component stations operating at the end of the fourth quarter 1998. Symbols are as in Table 1A. STA F LAT LONG EL NAME CHE 45 21 16.0 122 59 19.0 0.436 Chehalem, Oregon (Operated by UO) COR 44 35 08.5 123 18 11.5 0.121 Corvallis, Oregon (IRIS station, Operated by OSU) ELW % 47 29 38.8 121 52 21.6 0.267 Echo Lake, WA (operated by UW) ERW % 48 27 14.4 122 37 30.2 0.389 Mt. Erie, WA (operated by UW) GNW % 47 33 51.8 122 49 31.0 0.165 Green Mountain, WA (operated by UW) LON % 46 45 00.0 121 48 36.0 0.853 Longmire, WA (operated by UW) LTY % 47 15 21.2 120 39 53.3 0.970 Liberty, WA (operated by UW) NEW 48 15 50.0 117 07 13.0 0.760 Newport Observatory (USGS-USNSN) OCWA 47 44 56.0 124 10 41.2 0.671 Octopus Mtn. (USGS-USNSN) PIN 43 48 40.0 120 52 19.0 1.865 Pine Mt. Oregon (operated by UO) RAI 46 02 25.1 122 53 06.4 1.520 Trojan Plant, Oregon (OSU) RWW % 46 57 50.1 123 32 35.9 0.015 Ranney Well (operated by UW) SPW % 47 33 13.3 122 14 45.1 0.008 Seward Park, Seattle (operated by UW) TTW % 47 41 40.7 121 41 20.0 0.542 Tolt Reservoir, WA (operated by UW) WVOR 42 26 02.0 118 38 13.0 1.344 Wildhorse Valley, Oregon (USGS-USNSN)
Table 1C lists strong-motion, three-component stations operating in Washington and Oregon that provide data in real or near-real time to the PNSN. Several of these stations also have broad-band instruments, as noted. The "SENSOR" field designates what type of seismic sensor is used; A = Terra-Tech SSA-320 SLN triaxial accelerometer, BB = Guralp CMG-40T 3-D broadband velocity sensor. The "TELEMETRY" field indicates the type of telemetry used to recover the data. C = continuously telemetered via dedicated telephone lines, D = dial-up.
TABLE 1C Strong-motion three-component stations operating at the end of the fourth quarter 1998. Symbols are as in Table 1A. STA F LAT LONG EL NAME SENSORS TELEMETRY ERW % 48 27 14.4 122 37 30.2 0.389 Mt. Erie, WA A,BB C ELW % 47 29 38.8 121 52 21.6 0.267 Echo Lake, WA A,BB C MBPA % 47 53 56.6 121 53 20.2 0.186 Monroe BPA A20 C,D MPL % 47 28 08.2 122 11 06.2 0.122 Maple Valley A C,D NOWS % 47 41 12.0 122 15 21.2 0.00 NOAA, Bldg 3 A20 I QAW % 47 37 53.2 122 21 15.0 0.140 Queen Anne A C RAW % 47 20 14.0 121 55 57.6 0.208 Raver BPA A C,D SEA % 47 39 18.0 122 18 30.0 0.030 Seattle A,BB C,D SPW % 47 33 13.3 122 14 45.1 0.008 Seward Park, Seattle A,BB C TBPA % 47 15 28.1 122 22 05.9 0.002 Tacoma WA BPA A C,D UPS % 47 15 56.1 122 28 58.4 0.113 U. Puget Sound A D,I
The seismograph network operated by the University of Washington consists of small numbers of broad-band and strong-motion sensors, plus over 130 short-period, vertical component, real-time-telemetered seismographic stations. Using real-time-telemetry data, the PNSN seismic recording system operates in an `event triggered' mode, recording data at 100 samples per sec. per channel. Data from stations with other telemetry systems are retrieved and integrated with the event-triggered data. Arrival times, first motion polarities, signal durations, signal amplitudes, locations and focal mechanisms (when possible) are determined in post-processing. Digital data are processed for all teleseisms, regional events, and all locatable local events. Each trace data file has an associated `pickfile' which includes arrival times, polarities, coda lengths, and other data.
In 1998, EARTHWORM replaced the SUNWORM system as the main PNSN data-acquisition system. The SUNWORM system continues to operate as a backup system. Data processing continues to use our UW2 format data and the same analysis tools in place for the past several years.
Most PNSN broad-band stations record continuously, as well as having the ability to trigger and record on-site. Stations LTY, RWW, LON, and GNW record digitally on-site, and data are retrieved via dial-up modem. We also receive data for selected events via Auto-DRM from U.S. National Seismograph Network (USNSN) stations NEW; in north-eastern Washington, and WVOR; in south-eastern Oregon. Data for specific events are provided to the PNSN from broad-band stations PIN, DBO, COR, and RAI (operated by Oregon State University and the University of Oregon).
Broad-band data in "raw" formats are stored on ongoing "network-archive" backups along with all unedited network-trigger trace data. Broadband data are also archived in merged and edited UW2 format on our "Master Event" tapes along with data from the PNSN short-period network, Our "Master Event" files are also translated to IRIS-SEED format and submitted to the IRIS Data Management Center for archive and distribution. All of our "Master Event" tapes of seismic trace data from 1980-1998 have now been reformatted to the IRIS-SEED format and submitted to the IRIS Data Management Center, where they are made available through the standard request mechanisms of the IRIS data-base system.
PNSN Quarterly Reports since 1994 have included moment-tensor focal mechanisms for earthquakes larger than magnitude 3.5. These have been provided to us by Dr. John Nabelek of Oregon State University (OSU) under support from USGS NEHRP Grant 1434-93-G-2326. OSU also provides broad-band data for some events from stations COR and RAI. The University of Oregon (UO) provides broad-band data for some events (from stations PIN and DBO. Phase data for earthquakes in northern Washington and southern British Columbia are exchanged with the Canadian Pacific Geoscience Centre promptly for significant events. We also exchange data occasionally with the Montana Bureau of Mines, Boise State University, and CALNET. The entire PNSN catalog has been contributed to the CNSS composite catalog located at the Northern California Earthquake Data Center. The PNSN section of the CNSS catalog is updated daily.
Publications wholly or partly supported under this operating agreement are listed in Appendix 2.
Figure 2 shows earthquakes of magnitude 2.0 or larger located in Washington and Oregon during this reporting period. Table 2 lists earthquakes recorded by the PNSN during 1998 which were reported felt. For comparison purposes, Table 3 gives information on seismic activity recorded at the PNSN annually since 1980. During this reporting period there were 9 earthquakes reported felt west of the Cascades in Washington, ranging in magnitude from 1.7 to 4.0. Two earthquake were felt east of the Cascades. In Oregon, no earthquakes were reported felt.
TABLE 2 Felt Earthquakes during 1998 DATE-(UTC)-TIME LAT(N) LON(W) DEPTH MAG COMMENTS yy/mm/dd hh:mm:ss deg. deg. km 98/01/22 23:37:03 47.18N 121.93W 16.5 2.0 3.1 km ESE of Enumclaw, WA 98/02/12 00:15:39 47.66N 122.48W 29.8 3.0 13.1 km ESE of Poulsbo, WA 98/02/15 15:14:53 46.85N 121.96W 9.3 3.2 16.2 km W of Mount Rainier 98/03/03 04:19:02 49.15N 118.35W 0.6 4.0 76.4 km NNW of Colville, WA 98/04/27 07:00:16 48.73N 123.16W 57.8 3.0 26.1 km NNW of Friday Harbor, WA 98/06/24 15:53:17 47.75N 121.88W 4.0 2.5 7.9 km ENE of Duvall, WA 98/06/29 01:36:42 47.56N 120.81W 8.4 2.4 41.9 km WNW of Wenatchee, Wa 98/10/10 07:55:12 48.90N 122.18W 0.1 1.7 9.4 km N of Deming, WA 98/10/21 05:25:24 45.93N 122.06W 9.4 3.1 30.0 km SSE of Mount St. Helens 98/11/03 22:40:48 47.51N 122.76W 23.4 3.1 11.4 km WSW of Bremerton, WA 98/11/20 17:39:20 48.83N 122.18W 1.6 2.0 3.3 km NE of Deming, WA
During May through July of 1998, activity beneath the cone Mt. St. Helens increased greatly. Though still several orders of magnitude below the number of earthquakes and energy release during the 1980s' eruptive period, the activity was the highest seen since 1987. In 1998, the PNSN located over 4000 earthquakes, more than in any other year of the PNSN's operation. The large number of events in 1998 was due to the vigorous activity at Mount St. Helens, combined with an ability to record more data, and a much more sensitive triggering configuration than existed in the 1980s.
Table 3 includes the total number of events processed, including both locatable and unlocatable earthquakes and explosions (blasts), both within and outside the Pacific Northwest Seismograph Network area. The total number of events is approximately equal to the sum of the number of events outside the network, inside the network, and unlocated. It is not exact because a few earthquakes or blasts fall just outside the region that we defined as "Inside the Net" (117-125W, 42-49.5N) but were processed and flagged as if they were local events within the network. The total number of "Located" events within the PNSN Network is the sum of located earthquakes and located blasts.
The RACE system, discussed earlier, is a pager-based alarm system that updates earthquake locations mapped on a PC screen. When a "significant" event (magnitude 2.9 or larger) is located by the PNSN automatic systems, preliminary location and magnitude is sent within minutes to seismologists and the RACE system via pager. The same information is forwarded via fax and e-mail to others with critical need. A set of web-pages on earthquakes magnitude 3.3 and larger are automatically generated and linked to the PNSN web-site. These preliminary messages are rapidly followed by final processing and update of the RACE systems, faxes, e-mail, and web-site, within 20 minutes to an hour.
TABLE 3
Annual counts of events recorded by the PNSN, 1980-1998
Year Total # Out of Net Inside Net
Unlocated Located
Total EQs(#felt) Blasts
80 4576 253 1075 3246 2874(18) 372
81 5155 291 1474 3385 2672(29) 713
82 4452 329 1824 2297 1948(20) 349
83 4489 405 2338 1745 1356(15) 389
84 3144 267 1095 1780 1409(16) 371
85 3560 266 1168 2122 1890(16) 232
86 2554 318 452 1776 1594(21) 182
87 1981 537 127 1304 966(22) 338
88 2249 507 114 1624 1263(19) 361
89 2781 501 137 2136 1835(38) 301
90 3433 717 204 2505 2096(26) 409
91 3083 675 315 2085 1687(26) 398
92 3522 891 235 2381 1993(22) 388
93 5594 731 626 4224 3877(35) 347
94 6243 900 1518 3816 3424(28) 392
95 5354 959 1462 2915 2539(16) 376
96 4741 911 1192 2628 2214(39) 414
97 3881 728 904 2239 1992(35) 247
98 7463 831 2174 4430 4176(11) 254
Summary lists for all earthquakes located by the PNSN since 1969 are available via anonymous ftp on ftp.geophys.washington.edu in the pub/seis_net subdirectory. This information is also available via the PNSN World-Wide-Web(WWW) site.
TABLE 4 Quarterly Comparison of Methods of Accessing PNSN list of most recent earthquakes, M>=2.0 Access Method 96-D 97-A 97-B 97-C 97-D 98-A 98-B 98-C 98-D Finger Quake 63,000 66,800 95,000 97,000 118,063 124,000 113,400 122,400 113,400 World-Wide-Web 5,400 15,700 27,700 37,100 34,700 50,000 55,000 49,000 47,400
The PNSN has an educational outreach program to better inform the public, policy makers, and emergency managers about seismicity and natural hazards. We provide information sheets, lab tours, workshops, and media interviews, and have an audio library with several tapes, including a frequently updated "recent earthquakes" message. In addition to our normal background of informational work; including several thousand calls per quarter to our audio library; tours of the PNSN lab by hundreds of students, teachers, and parents; and outreach talks to numerous groups of all types; the PNSN representatives were intensely involved with both CREW , the Cascadia Regional Earthquake Workgroup and Project Impact. Both these projects are aimed at mitigation of earthquake damage, and the PNSN role in providing information on geologic hazards is crucial to the education and mitigation effort. The PNSN also worked with the USGS to develop an information sheet on the PNSN. This is the first of a series of information sheets highlighting the diverse services that regional networks provide, according to the varying geologic hazards of their regions.
Our World-Wide-Web site is an important element of our outreach, handling around 300,000 public contacts/quarter. An additional 400,000 Web-contacts/quarter are made through other earthquake-related pages hosted on the PNSN web-server; including the "CREW" Web-site, the very popular "Tsunami!" site, the "seismosurfing" page, and the "Council for the National Seismic System (CNSS)" Web-site
Seismic stations, telemetry links, and data acquisition equipment were maintained by Jim Ramey and Allen Strelow at the UW, Patrick McChesney (stationed at CVO in Vancouver, Washington), Pat Ryan (of the University of Oregon in Eugene, Oregon), and Don Hartshorn (of Pacific Northwest National Labs in Richland, WA). Bill Steele provided information to the public, while Sandra Corso handled routine data analysis and archiving of digital trace data in UW2 format. Dr. Peter Lombard assisted with EARTHWORM development. Ruth Ludwin wrote reports, maintained the PNSN web-pages, handled administrative tasks, and archived data in SEED format. Moment-tensor focal mechanisms for earthquakes larger than magnitude 3.5 were provided for our quarterly reports by Dr. John Nabelek of Oregon State University (OSU) under support from USGS NEHRP Grant 1434-93-G-2326. OSU also provides broad-band data from stations COR and RAI, which we archive with our trace-data files. The University of Oregon (UO) provides broad-band data from stations PIN and DBO.