We conducted multibeam bathymetric surveys crossing the northern Japan Trench offshore Sanriku and examined seafloor displacement by means of the difference in bathymetry before and after the 11 March 2011 Tohoku‐oki earthquake. The seafloor displacements were less than several meters in vertical displacement and less than 20 m in trench‐normal horizontal displacement; consequently, lower amplitude seafloor displacements were evaluated. Comparatively, the landward lower slope near the trench was uplifted, the middle slope was subsided, and the midslope terrace was depressed after the earthquake. Therefore, localized very large fault slip or very large submarine landslide is unlikely. Instead, smaller uplift of the lower slope near the trench extending broader along the trench seems to be plausible explanation for the devastating tsunami source in the northern Japan Trench area.

PurposeMotivation can serve as the engine that turns intention into action, and, as such, is indispensable in the early phase of the entrepreneurial process, where opportunity recognition and exploitation are key. However, research in this area has so far shed a selective spotlight on specific facets of entrepreneurial motivation, whereas the consideration of basic motives has been widely neglected. Hence, the purpose of this paper is to illuminate the basic motivational foundations of one core aspect of entrepreneurial behavior, namely opportunity recognition.Design/methodology/approachThe study examined how motivation influences the process of recognizing and exploiting entrepreneurial opportunities in a sample of 312 managing directors and managing partners of small and medium-sized enterprises. Opportunity recognition and exploitation were assessed by two different measures: one evaluating the objective number of recognized and realized business opportunities, the other assessing the perceived proficiency in identifying and exploiting entrepreneurial opportunities. Implicit and explicit facets of basic motivation were measured using a comprehensive assessment of human needs.FindingsFindings show that entrepreneurs' achievement motive is an important driver in both the identification and exploitation of opportunity. The power motive affects the perceived ability to exploit business opportunities. Interestingly, the explicit affiliation motive showed an inhibitory effect on the perceived ability of opportunity identification, whereas implicit affiliation motive is affecting the number of recognized and realized business opportunities positively.Originality/valueThis research clearly highlights the preeminence of basic motivational factors in explaining individual early-stage entrepreneurial behavior, making them a prime target for training interventions.

The continental slopes of the Black Sea show abundant manifestations of gas seepage in water depth of <720 m, but underlying controls are still not fully understood. Here, we investigate gas seepage along the Bulgarian and Romanian Black Sea margin using acoustic multibeam water column, bathymetry, backscatter, and sub-bottom profiler data to determine linkages between sub-seafloor structures, seafloor gas seeps, and gas discharge into the water column. More than 10,000 seepage sites over an area of ∼3,000 km2 were identified. The maximum water depth of gas seepage is controlled by the onset of the structure I gas hydrate stability zone in ∼720 m depth. However, gas seepage is not randomly distributed elsewhere. We classify three factors controlling on gas seepage locations into depositional, erosional, and tectonic factors. Depositional factors are associated with regionally occurring sediment waves forming focusing effects and mass-transport deposits (MTDs) with limited sediment drape. Elongated seafloor depressions linked to faulting and gas seepage develop at the base between adjacent sediment waves. The elongated depressions become progressively wider and deeper toward shallow water depths and culminate in some locations into clusters of pockmarks. MTDs cover larger regions and level out paleo-topography. Their surface morphology results in fault-like deformation patterns of the sediment drape on top of the MTDs that is locally utilized for gas migration. Erosional factors are seen along channels and canyons as well as slope failures, where gas discharge occurs along head-scarps and ridges. Sediment that was removed by slope failures cover larger regions down-slope. Those regions are devoid of gas seepage either by forming impermeable barriers to gas migration or by removal of the formerly gas-rich sediments. Deep-rooted tectonic control on gas migration is seen in the eastern study region with wide-spread normal faulting promoting gas migration. Overall, gas seepage is widespread along the margin. Gas migration appears more vigorous in shallow waters below ∼160 m water depth, but the number of flare sites is not necessarily an indicator of the total volume of gas released.

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