0000000000285276
AUTHOR
James Goff
History of ancient megathrust earthquakes beneath metropolitan Tokyo inferred from coastal lowland deposits
Abstract Metropolitan Tokyo is located directly above a subduction zone that has generated two megathrust earthquakes in the past 300 years. However, the timing of older megathrusts on this margin is poorly understood. In this study, we aim to constrain the timings of past megathrust earthquakes, using coastal stratigraphy, paleoecology, radiocarbon dating and archaeological records from coastal lowlands. An investigation of 13 boreholes in the southern coastal area of metropolitan Tokyo found evidence for 4 m of uplift in a 6000-year period. However, we found that net vertical displacement in the last 1000 years is approximately zero. Results suggest that preservation of usually ephemeral …
Could tsunami risk be underestimated using core‐based reconstructions? Lessons from ground penetrating radar
Where should we take cores for palaeotsunami research? It is generally considered that local depressions with low energy environments such as wetlands are one of the best places. However, it is also recognized that the presence or absence of palaeotsunami deposits (and their relative thickness) is highly dependent upon subsoil microtopography. In the beach ridge system of Ishinomaki Plain, Japan, several palaeotsunami deposits linked to past Japan Trench earthquakes have been reported. However, the number of palaeotsunami deposits reported at individual sites varies considerably. This study used ground penetrating radar (GPR) combined with geological evidence to better understand the relati…
Major typhoon phases in the upper Gulf of Thailand over the last 1.5 millennia, determined from coastal deposits on rock islands
Abstract Rapid growth of Asian megacities, exemplified by the megacity of Bangkok, Thailand, with a population of over 10 million inhabitants, means that an increasing number of people are living in low-lying coastal areas exposed to hazards such as typhoons. While Bangkok has always been considered not to be at risk from typhoon strikes, recent discoveries of elevated carbonate boulder deposits have started to question this assumption. This work reports on findings from the islands of Ko Khang Khao and Ko Phai, farther north and west than earlier studies, and adds to the existing body of evidence for prehistorical typhoon-driven high energy marine inundation (HEMI) events penetrating north…