HR: 1330h
AN: S12B-0384    [PDF]
TI: Refined Slip History of the North Anatolian Fault at Gerede on the 1944 rupture
AU: * Okumura, K
EM: kojiok@hiroshima-u.ac.jp
AF: Hiroshima University, Kagamiyama 1-2-3, Higashi-Hiroshima, 739-08522 Japan
AU: Rockwell, T K
EM: trockwell@geology.sdsu.edu
AF: Department of Geological Sciences, San Diego State University, San Diego, CA 92182 United States
AU: Duman, T
EM: tduman@mta.gov.tr
AF: MTA Geological Research Department, Eskisehir Yolu, Ankara, 06520 Turkey
AU: Tokay, F
EM: ftokay@mta.gov.tr
AF: MTA Geological Research Department, Eskisehir Yolu, Ankara, 06520 Turkey
AU: Kondo, H
EM: kondoh@hiroshima-u.ac.jp
AF: Hiroshima University, Kagamiyama 1-2-3, Higashi-Hiroshima, 739-08522 Japan
AU: Yoldirim, C
EM: cengizyildirim@mta.gov.tr
AF: MTA Geological Research Department, Eskisehir Yolu, Ankara, 06520 Turkey
AU: Ozaksoy, V
EM: volkano@mta.gov.tr
AF: MTA Geological Research Department, Eskisehir Yolu, Ankara, 06520 Turkey
AB: We excavated four new fault crossing trenches and a complex of fault parallel trenches at Ardicli, 15 km east of Gerede on the 1944 Bolu-Gerede segment of the North Anatolian fault to resolve timing and slip in past earthquakes. A unique large gravel-filled channel (unit 10) was determined to be offset 17 to 20 m. Preliminary age control on the gravel shows it dates to the 6th or 7th century AD. Fault crossing trenches show evidence for 5 events after deposition of unit 10. Preliminary 14C dates place the earlier 3 of 5 events at AD 643-918 (EV5), AD 943-1298 (EV4), and AD 1171-1668 (EV3). These 3 events are recorded in 3 clayey units (8, 6, and 4). EV3 is the best represented with disruption into the base of unit 4 and on the main and subsidiary faults. The two most recent events are the 1944 (E1) and presumably the great 1668 earthquake (E2). Based on the offset of small channels cutting into the unit 4 surface at the site, slip in 1944 and 1668 was 5 +/- 1 m in each event. This suggests that the prior 3 events collectively produced 7 to 10 m slip, slightly less than that which occurred in the most recent events. EV4 may be correlated with 1050 earthquake, but no catalog has mentioned about EV5 and EV3, indicating that historic records of the large North Anatolian fault earthquakes are incomplete for this period. The finding of EV3 is important for the analysis of earthquake cycles. According to the catalogs, the interval of 618 years between 1050 and 1668 was much longer than the 1668-1944 interval and that around the Marmara Sea. With EV3, the recurrence may be much more periodic. Our detailed studies on the repeated slips along the 1944 segment indicate the slips during past 5 earthquakes are similar. The 1944 segment, especially in its central portion around Gerede is quite unique and straight. The refined slip history here will help to define regularity and irregularity of earthquake recurrence.
UR: http://www.home.hiroshima-u.ac.jp/kojiok
DE: 7221 Paleoseismology
DE: 7223 Seismic hazard assessment and prediction
SC: Seismology [S]
MN: 2003 Fall Meeting