An objective method for the production of isopach maps and implications for the estimation of tephra deposit volumes and their uncertainties.
An objective method for the production of isopach maps and implications for the estimation of tephra deposit volumes and their uncertainties.
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DOI：
10.1007/s00445-015-0942-y
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发表时间：
2015
影响因子：
3.5
通讯作者：
Sparks, R. S. J.
中科院分区：
文献类型：
--
作者：
Engwell, S. L.;Aspinall, W. P.;Sparks, R. S. J.
通过对矿床的解释来确定火山爆发过程的特征，是评估火山灾害和风险的关键，特别是对于不经常发生的大规模爆发和那些在地质记录中矿床是短暂的火山。虽然火山喷发的规模，通过测量和解释火山灰瀑布沉积物是特别重要的，这种测量和体积估计的不确定性很少提出。在这里，火山灰体积的估计是来自等厚图，通过模拟原始厚度数据作为三次B样条曲线下的张力。等厚线是相对于原始数据客观确定的，并使从出版的地图进行体积估计的局限性进行调查。使用样条等厚线得出的喷发量与选定的已发表估计值相差15- 40%，反映了体积估计过程中的不确定性。形式化的分析能够识别不确定性的来源;喷发体积的不确定性（> 30%）远大于厚度测量的不确定性（~ 10%）。无论等厚线生产采用何种方法，测量次数都是体积估算不确定性的关键因素。使用三次B样条方法处理的矿床通过分布在每个存款上的60个测量值进行了很好的描述;然而，该数字取决于存款和分布，对于几何形状复杂的矿床，例如呈现双叶分散的矿床，该数字会增加。本文的在线版本（doi：10.1007/s 00445 -015-0942-y）包含补充材料，可供授权用户使用。
Characterization of explosive volcanic eruptive processes from interpretation of deposits is a key for assessing volcanic hazard and risk, particularly for infrequent large explosive eruptions and those whose deposits are transient in the geological record. While eruption size—determined by measurement and interpretation of tephra fall deposits—is of particular importance, uncertainties for such measurements and volume estimates are rarely presented. Here, tephra volume estimates are derived from isopach maps produced by modeling raw thickness data as cubic B-spline curves under tension. Isopachs are objectively determined in relation to original data and enable limitations in volume estimates from published maps to be investigated. The eruption volumes derived using spline isopachs differ from selected published estimates by 15–40 %, reflecting uncertainties in the volume estimation process. The formalized analysis enables identification of sources of uncertainty; eruptive volume uncertainties (>30 %) are much greater than thickness measurement uncertainties (~10 %). The number of measurements is a key factor in volume estimate uncertainty, regardless of method utilized for isopach production. Deposits processed using the cubic B-spline method are well described by 60 measurements distributed across each deposit; however, this figure is deposit and distribution dependent, increasing for geometrically complex deposits, such as those exhibiting bilobate dispersion. The online version of this article (doi:10.1007/s00445-015-0942-y) contains supplementary material, which is available to authorized users.
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影响因子：
3.9
作者：
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DOI：
10.1016/j.jvolgeores.2015.03.009
发表时间：
2015-04-15
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作者：
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