USA

USA California Earthquake Oct 1989 UNDRO Information Reports 1-4

Format
Situation Report
Source
Posted
Originally published


UNDRO 89/2147

USA CALIFORNIA - EARTHQUAKE
UNDRO INFORMATION REPORT NO. 1
18 OCTOBER 1989

1. A STRONG EARTHQUAKE, MEASURING 6.9 ON THE RICHTER SCALE, HIT CALIFORNIA STATE ON 17 OCT 89 AT 17:04 LOCAL TIME (18 OCT 89 00:04 HRS GMT).

2. THE EARTHQUAKE LASTED 15 SECONDS AND THE EPICENTER HAS BEEN LOCATED IN THE AREA OF SANTA CRUZ TOWN, 80 KM SOUTH OF SAN FRANCISCO CITY, ALONG ST. ANDREAS FAULT. THE EARTHQUAKE SEVERELY AFFECTED AN AREA OF 160 KM RADIUS FROM SAN FRANCISCO.

3. FIRST REPORTS FROM THE CALIFORNIA OFFICE OF EMERGENCY SERVICES INDICATE THE PROVISIONAL NUMBER OF 250 KILLED AND 500 INJURED.

4. MAJOR DAMAGES TO BUILDINGS AND INFRASTRUCTURES REPORTED. MOST OF DEATHS OCCURRED DUE TO COLLAPSE OF UPPER ROAD OF SAN FRANCISCO CITY HIGHWAY NETWORK. 400 PEOPLE INJURED IN COLLAPSE OF CENTRAL SECTION OF THE BAY BRIDGE.

5. MANY FIRES REPORTED DUE TO FRACTURES OF GAS SUPPLY PIPELINES IN GOLDEN GATE BRIDGE AREA.

6. IN SANTA CRUZ CITY SEVERAL BLOCKS ARE REPORTED ON FIRE AND MANY BUILDINGS COLLAPSED CREATING HEAVY RESCUE PROBLEMS.

7. OFFICE OF PRESIDENT IN WASHINGTON D.C IMMEDIATELY ESTABLISHED SPECIAL UNIT TO DEAL WITH EMERGENCY.

8. MORE DETAILED INFORMATION EXPECTED WHEN REPORTS AVAILABLE FROM OTHER TOWNS AFFECTED BY EARTHQUAKE.

9. CALIFORNIA OFFICIALS ESTIMATED DAMAGE AT 1 BILLION US. DLRS.

10. UNDRO FOLLOWING CLOSELY SITUATION IN CONTACT WITH US SCIENTIFIC AGENCIES AND RELEVANT GOVT BODIES.

= ESSAAFI UNDRO GENEVA 28148 +

(DPR 310 USA 89(1))


UNDRO 89/2155
USA CALIFORNIA - EARTHQUAKE
UNDRO INFORMATION REPORT NO.2
18 OCTOBER 1989

1. THE US GEOLOGICAL SURVEY REPORTS THAT THE EARTHQUAKE OCCURRED ALONG THE SAN ANDREAS FAULT IN THE SANTA CRUZ MOUNTAINS IN VICINITY OF LOMA PRIETA, APPROXIMATELY 16 KM NORTHEAST OR SANTA CRUZ, 29 KM SOUTH OF SAN JOSE, AND 80 KM SOUTHEAST OF SAN FRANCISCO. THIS IS THE LARGEST EARTHQUAKE TO OCCUR IN THE SAN FRANCISCO BAY AREA SINCE THE CATASTROPHIC EVENT OF 1906.

2. HUNDREDS OF SMALLER AFTERSHOCKS HAVE OCCURRED ALONG A 57 KM LONG STRETCH OF THE SAN ANDREAS FAULT BETWEEN LOS GATOS AND SAN JUAN BAUTISTA. THERE IS A 10 TO 20 PER CENT POSSIBILITY THAT ONE OR MORE AFTERSHOCKS COULD REACH MAGNITUDE AS LARGE AS 6.0 IN THE FIRST 24 HOURS FOLLOWING THE MAIN SHOCK AND DIMINISHING THEREAFTER.

3. PRELIMINARY REPORTS INDICATE EXTENSIVE DAMAGES IN SAN FRANCISCO, OAKLAND, SAN MATEO, SANTA CLARA, SAN JOSE, SANTA CRUZ, BERKELEY, HOLISTER AND SILICON VALLEY. THIS EARTHQUAKE OCCURRED IN SAME GENERAL AREA NEAR LAKE ELSMAN ALONG INTERSECTION OF THE SAN ANDREAS AND SARGENT FAULTS.

4. THE EARTHQUAKE REACTIVATED A ONCE-DORMANT SEGMENT OF THE SAN ANDREAS FAULT AND OPENED UP A 40 TO 50 KM LONG FISSURE NORTH OF SANTA CRUZ, REAWAKENING A FAULT THAT HAD BEEN STABLE SINCE 1906.

5. CALIFORNIA OFFICE OF EMERGENCY SERVICES INDICATED A NEW PROVISIONAL FIGURE OF 271 KILLED. 253 OF THE VICTIMS LOST THEIR LIVES IN THE COLLAPSE OF THE TWO-TIER 880 HIGHWAY.

6. THE AMERICAN RED CROSS INFORMS THAT THEY ARE NOT IN NEED OF EXTERNAL ASSISTANCE AND DO NOT WISH TO ACCEPT ANY DONATION IN KIND.

7. NATO HQ IN BRUSSELS REPORTED ITS READINESS TO ASSIST IF REQUIRED.

8. SAN FRANCISCO AIRPORT SERIOUSLY DAMAGED AND CLOSED TO AIR-TRAFFIC.

9. THE US DEFENCE DEPARTMENT MOBILIZED ALL FORCES TO AID DISASTER RELIEF EFFORTS IN STRICKEN AREAS. A NAVY CONSTRUCTION BATTALION WITH HEAVY-LIFT EQUIPMENT ASSISTING RESCUE EFFORTS AT COLLAPSED HIGHWAY, WHILE A NAVY FRIGATE STANDING BY IN SAN FRANCISCO BAY TO PUMP WATER FOR FIREMEN IF NECESSARY. HELICOPTERS FROM TWO OTHER NAVY SHIPS FERRYING EMERGENCY SUPPLIES AND INJURED.

= ESSAAFI UNDRO GENEVA 28148 +

(DPR 310 USA 89(1)


UNDRO 89/2160
USA CALIFORNIA - EARTHQUAKE
UNDRO INFORMATION REPORT NO. 3
19 OCTOBER 1989

1. LATEST REPORTS RECEIVED FROM THE CALIFORNIA OFFICE OF EMERGENCY SERVICES INDICATE PROVISIONAL NUMBER OF 273 KILLED AND 650 INJURED.

2. TWO AFTERSHOCKS, RECORDED AT 4.2 AND 5.0 ON THE RICHTER SCALE, HIT SAN FRANCISCO BAY AREA ON 19 OCT 89 AT 10:00 HRS GMT AND PRELIMINARY EPICENTERS HAVE BEEN LOCATED 90 KM SOUTH OF SAN FRANCISCO. NO ADDITIONAL DAMAGE REPORTED SO FAR.

3. THE EARTHQUAKE HAS BEEN CAUSED BY A RELEASE OF ENERGY FOLLOWING THE BLOCKAGE OF THE MOVEMENT IN THE ROCKY PLATES DEEP IN THE EARTH ALONG THE PORTION OF THE SAN ANDREAS FAULT THAT RUNS BENEATH SAN FRANCISCO. THE TWO MASSIVE ROCK SHELVES WHOSE EDGES MEET ALONG THE FAULT, THE NORTH AMERICAN PLATE AND THE PACIFIC PLATE, HAVE BEEN SLOWLY SLIPPING AGAINST EACH OTHER ALONG MOST OF THE FAULT. IN SAN FRANCISCO AREA THERE HAS BEEN NO SLIPPAGE SINCE THE GREAT EARTHQUAKE OF 1906. THE BLOCKAGE HAS BEEN BUILDING UP TENSION ALONG THE PORTION OF THE FAULT, WHICH
RESULTED IN THE SUDDEN RELEASE OF THE STRESS ON 17 OCT 89.

4. THE U.S FEDERAL EMERGENCY MANAGEMENT AGENCY REPORTED THAT ON 18 OCT PRESIDENT BUSH ORDERED FEDERAL AID FOR VICTIMS OF THE CALIFORNIA EARTHQUAKE AND DECLARED PART OF THE STATE MAJOR DISASTER AREA.

5. U.S. FEDERAL ASSISTANCE INCLUDES TEMPORARY HOUSING, GRANTS, LOW-COST LOANS AND OTHER PROGRAMS TO HELP INDIVIDUALS RECOVER FROM EFFECTS OF EARTHQUAKE. FEDERAL ASSISTANCE WILL ALSO BE AVAILABLE TO LOCAL CALIFORNIA GOVT TO COVER PART OF COST FOR DEBRIS REMOVAL, EMERGENCY PROTECTIVE MEASURES AND REPAIR OF DAMAGED PUBLIC PROPERTY.

6. THE GOVERNMENTS OF CANADA, GREECE, GREAT BRITAIN, JAPAN AND SOVIET UNION OFFERED TO SEND RESCUE TEAMS AND EMERGENCY ASSISTANCE IF REQUESTED.

= ESSAAFI UNDRO GENEVA 28148 +

(DPR 310 USA 89(1))


UNDRO 89/2180

USA CALIFORNIA - EARTHQUAKE
UNDRO INFORMATION REPORT NO. 4
23 OCTOBER 1989

1. THE CALIFORNIA OFFICE OF EMERGENCY SERVICES REPORTED THAT THE CONFIRMED DEATH TOLL FROM THE QUAKE IS 59 VICTIMS RECORDED SO FAR. IT IS EXPECTED THAT THE TOTAL NUMBER OF VICTIMS WILL NOT EXCEED 120 SINCE FIREMEN AND RESCUE TEAMS FOUND FAR FEWER CARS THAN EXPECTED UNDER THE COLLAPSED HIGHWAY 880. THE NUMBER OF INJURED IS REPORTED TO BE ABOUT 2,500, WHILE 6,000 PEOPLE WERE LEFT HOMELESS.

2. THE US RED CROSS ADVISES THEY ARE NOT MAKING AN INTERNATIONAL APPEAL AND REQUESTS ALL DONORS NOT TO SEND GIFTS IN KIND OR PERSONNEL.

3. HEAVY DAMAGE IN THE SAN FRANCISCO BAY AREA IS CONCENTRATED IN AREAS OF RECLAIMED LAND THAT HISTORICALLY HAS NOT WITHSTOOD WELL THE SHAKING FROM PREVIOUS EARTHQUAKES IN 1865, 1868 AND 1906.

4. THE US GEOLOGICAL SURVEY REPORTED THAT THE SECTION OF THE SAN ANDREAS FAULT THAT RUPTURED IN THIS EARTHQUAKE, AS DEFINED BY THE AFTERSHOCKS, EXTENDS FROM THE HIGHWAY 17 CROSSING (NEAR LEXINGTON
RESERVOIR) AT THE NORTH TO PAJARO GAP (NEAR THE HIGHWAY 101 CROSSING) AT THE SOUTH. THE EPICENTER OF THIS RUPTURE IS IN THE SANTA CRUZ MOUNTAINS, NEAR LOMA PRIETA, ABOUT 16 KM NORTHEAST OF THE CITY OF SANTA CRUZ. PRELIMINARY ESTIMATES PUT THE MAGNITUDE OF THE MAINSHOCK AT 6.9. THIS IS THE FIRST EARTHQUAKE LARGER THAN MAGNITUDE 5.0 TO RE-RUPTURE ANY PART OF THE 1906 EARTHQUAKE FAULT BREAK. RUPTURE IN THE 1906 QUAKE EXTENDED FOR 432 KM, FROM THE SOUTHERN END OF OCT 17 EARTHQUAKE, NORTHWARD TO CAPE MENDOCINO. BY COMPARISON, ONLY ABOUT 49 KM OF THE FAULT RUPTURED
DURING THE SANTA CRUZ EARTHQUAKE.

5. THOUSANDS OF AFTERSHOCKS FROM THIS EARTHQUAKE HAVE BEEN RECORDED. THE EPICENTER OF THE MAIN SHOCK IS NEAR THE ZONE OF INTENSE AFTERSHOCK ACTIVITY. FOCAL DEPTHS OF THESE AFTERSHOCKS EXTEND FROM NEAR THE GROUND SURFACE TO ABOUT 16 KM BELOW THE GROUND SURFACE. THERE WERE SIX MAGNITUDE 3.5 OR LARGER AFTERSHOCKS ON 19 OCT, ALL LOCATED NEAR THE SOUTHEAST END OF THE AFTERSHOCKS ZONE: THE LARGEST WAS A MAGNITUDE 5.0 SHOCK AT 3:14 AM LOCAL TIME.

6. THE TIME CHARACTERISTICS OF THE AFTERSHOCK SEQUENCE ARE SIMILAR TO THOSE OF THE AVERAGE HISTORIC CALIFORNIA SEQUENCE. THE RATE OF AFTERSHOCK OCCURRENCE DECREASES WITH TIME AFTER THE MAINSHOCK.

7. THIS IS UNDRO FINAL INFORMATION REPORT ON THE 17 OCTOBER 1989 - CALIFORNIA - EARTHQUAKE.

= ESSAAFI UNDRO GENEVA 28148 +

(DPR 310 USA 89(1)