The relationship between P‐wave velocity (V_p) and unconfined compressive strength (C₀) can be used to estimate in situ rock strength and stresses at depth in subduction zones. However, few reliable data on the V_p‐C₀ relationship in deep accretionary prism sediments are available. Here, we determined the V_p‐C₀ relationship down to ∼3.2 km in the Nankai accretionary prism from V_p measurements and indentation tests of drill cuttings retrieved from International Ocean Discovery Program Site C0002. In our results, the Nankai accretionary prism sediments tended to be weaker compared with estimates obtained by using other empirically determined V_p‐C₀ relationships. We also examined the relationship between V_p and porosity in the accretionary prism. The V_p‐porosity relationship obtained by using only data of Nankai accretionary prism sediments showed that V_p generally increased with decreasing porosity; this result is consistent with published V_p‐porosity relationships for Nankai Trough sediments. The empirical relationships derived in this study should improve estimates of stress state, pore pressure, and fault strength in the Nankai accretionary prism.

中文翻译：

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南开增生棱镜的机械弱点：从钻屑的Vp测量中得出的见解

之间的关系P -wave速度（V _p（）和无侧限抗压强度Ç ₀）可被用于在俯冲带在深度原位岩石强度和应力来估计。但是，关于深层增生棱镜沉积物中V _p - C ₀关系的可靠数据很少。在这里，我们确定了从V _p到南开增生棱镜中低至〜3.2 km的V _p - C ₀关系。从国际海洋发现计划网站C0002中检索到的钻屑的测量和压痕测试。在我们的结果中，与使用其他凭经验确定的V _p - C ₀关系获得的估计值相比，南开增生棱镜沉积物往往较弱。我们还研究了增生棱镜中V _p和孔隙率之间的关系。仅使用南开增生棱镜沉积物的数据获得的V _p孔隙率关系表明，V _p通常随孔隙度的降低而增加；该结果与公布的V _p一致南开海槽沉积物的孔隙度关系。这项研究得出的经验关系应该可以改善对南开增生棱镜的应力状态，孔隙压力和断层强度的估计。