Steve Bergman, Instructor
Kobe, Japan: 17 Jan 1995 (
) chokkagata -EQ with epicenter directly under city
Fault & Plate Tectonics Trench-parallel Nojima Right-Lateral Strike-Slip Fault, 200 km from the main EURasia-PHIlippine
Plate subduction zone boundary. Total length of surface rupture zone ~60 km Depth to Hypocenter ~ 10-15 km
Maximum Horizontal Offset ~1.7 m (local minor vertical offset of <1.3 m)
Time & Duration At 5:46 AM Tues; shaking duration 15-20 sec. (some soft sediment areas strongly shook for 100 sec.)
Magnitude & Intensity M
S
=6.8, M w
= 6.9; MMI=X-XI.
Impact & Other Effects 6,432 people killed, 37,000 injured, 310,000 homeless (of the city's 1.5 million); >152,000 buildings collapsed or ruined; ~$200 billion damages (~3% of Japan GDP, most costly disaster in human history ); docks of the 3 rd busiest port in the world were severely damaged due to liquefaction (only 8 of 186 berths survived); extensive liquefaction near coast (<3 m settling); extensive fires (>150) consumed over 70 US blocks; severely impaired infrastucture damaging highways, railroads, water, sewer, gas, and power lines. High losses caused by 4 factors: rupture directivity toward city center, basin edge soft sediment effects, poor building construction, & poor emergency response. Nikkei Index dropped ~6% in one day; many banks folded; the economy has taken many years to recover, and frequencies of suicides, spousal abuse and alcoholism all increased.
Recurrence Interval ~1000 years for much larger "great" earthquake; previous EQ: 1596 M w
= 7, 1916 M w
= 6.1;
Selected references
Aoki, Y; Scholz, CH (2003) Interseismic deformation at the Nankai subduction zone and the Median Tectonic Line, SW Japan J.
Geophys. Res., 108, B10, 2470
Gutscher, MA & Lallemand, S (1999) The birth of a major strike slip fault system in SW Japan. Terra Nova , 11, 203-9.
Pollitz F & Sacks, SI (1997). The 1995 Kobe Japan earthquake, a long delayed aftershock of the offshore 1944 Tonankai and 1946 Nankaido earthquakes. Bull. Seism. Soc. Amer ., 87, 1-10.
Izmit, Turkey: 17 Aug 1999 (Kocaeli)
Fault & Plate Tectonics Four separate right en-echelon ~25 km long step-over segments associated with the 1600 km long North
Anatolian Right-Lateral Strike Slip Fault (NAF, ~2.4 cm/yr), bounding the ANAtolian and EURasian plates (these were the 7 th &
8 th westward migrating major EQ, M>6.8 since 1939). The westward ‘extrusion’ motion of the Anatolian block is caused by the northward collision of the ARAbian plate with Eurasia. The NAF is sub-parallel to the INDia-EUR plate boundary.
Total length of surface rupture zone Izmit~125 km; {Düzce~40 km}.
Total area of sub-surface rupture zone Izmit: 125x12 km= 1500 km 2 and {Düzce: 40x14km=560 km 2 }.
Depth to Hypocenter 17 km, {Düzce-10 km}
Maximum Horizontal Offset Izmit~5 m; {Düzce 4 m} Vertical Offset {Düzce 3 m}
Time & Duration At 3:01 AM Tues
Magnitude & Intensity M
B
=6.3, M
S
=7.8, M w
= 7.4; {Düzce M
S
=7.3, M w
= 7.2}; MMI=X.

Combined Impact & Other Effects ~30,000 people killed (1,000 in Istanbul, 90 km west, pop 10 million), 44,000 injured;
300,000 homeless; 120,000 buildings collapsed or ruined; ~$20 billion damages (~10% of Turkey GDP); Oil refineries caught fire, leaking gas ignited explosions, extensive liquefaction and ground settling; and health workers from > 21 countries battled to prevent the spread of typhoid fever, cholera and dysentery.
Recurrence Interval ~450 yrs based on the last 2000 years.
Selected reference : USGS (2000) Implications for Earthquake Risk Reduction in the United States from the Kocaeli,
Turkey, Earthquake of August 17, 1999. Circular 1193; http://www.eqe.com/revamp/turkey2.htm
Bam, Iran: 26 Dec 2003
Fault & Plate Tectonics N-S Bam Right-Lateral Strike Slip Fault, splay of the NW-SE Gowk reverse fault, near the main boundary between the northward moving (3 cm/yr) ARAbian plate - EURasian Plate collision zone. The Bam EQ gap had no historic EQ until this event.
Total length of surface rupture zone 50-100 km Depth to Hypocenter 10 km
Maximum Horizontal Offset ~1.2 m (local minor vertical offset of 1.3 m)
Time & Duration At 5:27 AM Thurs; shaking duration-15 sec. The quake was preceded by a foreshock the night before causing many people to sleep outdoors, saving many lives.
Magnitude & Intensity M w
= 6.6; Maximum MMI=IX.
Impact & Other Effects >31,000 people killed, the >2000 year old Arg-e Bam citadel (@ 6 km 2 , largest mud-brick complex in the world) was destroyed, >50,000 injured, >100,000 homeless; >70% of the houses destroyed; peak acceleration 0.7-0.8g (horiz)
1g (vertical); estimated cost of rebuilding >$1 billion
Recurrence Interval ~2000 years; previous EQ on the nearby Gowk Fault: Sirch 1981 M w
= 6.6 (3000 deaths),
Golbaf 1981M w
= 7.3 (1500 deaths).
Sources : http://www.iiees.ac.ir/English/bam_report_english_recc.html
, & http://www.ngdir.ir