Characteristic Earthquakes in the Southern Dead Sea Transform? Evidence from Paleoseismology, Historical Records, Archaeology, and Instrumental Seismicity

ABSTRACT

The hypothesis of repeated large “characteristic” earthquakes displaying a narrow size range, occurring more frequently on individual faults or fault segments than predicted from the Gutenberg–Richter empirical relation, has long prompted scientific debate. The hypothesis emerged from paleoseismic investigations in the western United States and Japan, and their integration with instrumental data. Growing evidence suggests that characteristic earthquakes better reflect Holocene seismic cycles than the log-linear Gutenberg–Richter frequency–magnitude relation. Yet, these observations are limited by the availability and precision of preinstrumental sources, and some suggest more complex fault behavior. Here, we evaluate historical recurrence patterns along the Dead Sea transform (DST), a ∼1000 km long plate boundary, by analyzing a unique integrated dataset comprising instrumental, historical, archaeological, and paleoseismic sources. We compile the most destructive earthquakes and assess the resulting magnitude distribution. The integration with microseismicity from the last ∼40 yr reveals that magnitude (M) ≥ 7.0 earthquakes occur more frequently than predicted by the instrumental Gutenberg–Richter relation, notwithstanding the large uncertainties. We also note the relative scarcity of smaller, M ∼ 6.0–6.9 earthquakes. These findings establish a characteristic seismic behavior during the past ∼2000 yr. However, a few exceptionally large earthquakes (749, March 1068, 1202, November 1759 C.E.), which deviate from the classical definition of characteristic earthquakes with a “relatively narrow range of magnitudes near the maximum magnitude,” align with uncharacteristic observations (e.g., the 2011 Tohoku-Oki earthquake) and suggest bimodal or multimodal earthquake size groups. We conclude that historical earthquakes in the characteristic size range of M ∼ 7.0–7.3 are most typical of the DST, with less frequent, larger (M ∼ 7.4–7.7, possibly ∼7.4–8.0) earthquakes. These findings reconcile both sides of the ongoing debate and are required for sound, empirically driven seismic hazard analyses, regionally and beyond.