In August 2010, Sinabung volcano began erupting after more than a thousand years of dormancy. Following several weeks of phreatic eruptions, the eruptions ceased and Sinabung entered what became an inter-eruptive period of dominantly seismic unrest. While standard equations for understanding the size of an earthquake (local magnitude (M L ), coda magnitude (M C ), and seismic energy release (E R )) have long been developed, it is best practice to fine tune these relations for a given region and period of study to more accurately describe seismicity and to directly compare it with other volcanic systems. More accurate descriptions of magnitudes and energy release are vital to accurate volcanic eruption forecasting and evaluation of seismic and volcanic risk. In this study, we use high-frequency volcano-tectonic (VT) earthquakes recorded on a temporary three-component network installed between October 2010 and December 2011 in the region around Sinabung volcano to better constrain the seismic parameters of and better understand this previously unstudied volcano. We determine region-specific formulas for M L , M C , and E R as follows: M L = log 10 A + 1.1252 log 10 r + 0.0280 r − 2.5427 , M C = 0.7764 log 10 t coda + 0.0676 r − 0.7185 , and log 10 E R = 1.5720 M L + 11.5258 , $$ {\mathrm{M}}_{\mathrm{L}}={\log}_{10}A+1.1252{\log}_{10}r+0.0280\ r-2.5427,\kern0.5em {\mathrm{M}}_{\mathrm{C}}=0.7764\ {\log}_{10}{t}_{coda}+0.0676\ r-0.7185,\kern0.5em \mathrm{and}\kern0.5em {\log}_{10}\left({\mathrm{E}}_{\mathrm{R}}\right)=1.5720{\mathrm{M}}_{\mathrm{L}}+11.5258, $$ where A , r , and t coda are maximum amplitude on a Wood-Anderson seismogram, hypocentral distance (km), and the coda duration (s), respectively. Constants in the M L equation have physically interpretable meanings. The constant for the geometrical spreading term (log 10 r term) equals one for perfect spherical spreading of the waveform. Our value is greater than one and thus suggests that wavefronts spread at a slightly different rate than for simple spherical spreading. The constant for the attenuation term ( r term) is consistent with locally mapped attenuative deposits (limestones and tuffs) and previous 3D tomographic results. Our M C equation differs from a previous study, likely because different data in a different time period were used. Earthquake hypocenters are consistent with those located in previous tomographic studies, and we interpret the earthquakes in this study as distal VT earthquakes induced by continued magmatic intrusion at Sinabung over the period of October 2010–December 2011.

中文翻译：

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2010年10月至2011年12月印度尼西亚锡纳朋火山火山构造地震的局地震级、震级和辐射能

2010 年 8 月，锡纳朋火山在休眠了一千多年后开始喷发。在经历了数周的潜水喷发后，喷发停止了，锡纳朋进入了一个以地震动荡为主的喷发间期。虽然用于理解地震大小（局部震级 (ML)、尾波震级 (MC) 和地震能量释放 (ER)）的标准方程早已被开发出来，但最佳做法是微调给定区域的这些关系和更准确地描述地震活动并直接将其与其他火山系统进行比较。更准确地描述震级和能量释放对于准确预测火山喷发以及评估地震和火山风险至关重要。在这项研究中，我们使用在 2010 年 10 月至 2011 年 12 月期间在锡纳朋火山周围地区安装的临时三分量网络上记录的高频火山构造 (VT) 地震，以更好地约束和更好地了解这个以前未研究过的火山的地震参数。我们确定 ML 、MC 和 ER 的区域特定公式如下： ML = log 10 A + 1.1252 log 10 r + 0.0280 r − 2.5427 ，MC = 0.7764 log 10 t coda + 0.0676 r 8 − 0,7 log = 8 − 0. 1.5720 ML + 11.5258 , $$ {\mathrm{M}}_{\mathrm{L}}={\log}_{10}A+1.1252{\log}_{10}r+0.0280\ r-2.5427, \kern0.5em {\mathrm{M}}_{\mathrm{C}}=0.7764\ {\log}_{10}{t}_{coda}+0.0676\ r-0.7185,\kern0.5em \mathrm {and}\kern0.5em {\log}_{10}\left({\mathrm{E}}_{\mathrm{R}}\right)=1.5720{\mathrm{M}}_{\mathrm{ L}}+11.5258, $$ 其中 A , r , 和 t coda 分别是 Wood-Anderson 地震图上的最大振幅、震源距离 (km) 和尾声持续时间 (s)。ML 方程中的常数具有物理上可解释的含义。几何扩展项（log 10 r 项）的常数等于波形完美球形扩展的 1。我们的值大于 1，因此表明波前的传播速率与简单的球形传播略有不同。衰减项（r 项）的常数与局部绘制的衰减沉积物（石灰岩和凝灰岩）和之前的 3D 断层扫描结果一致。我们的 MC 方程与之前的研究不同，可能是因为使用了不同时间段的不同数据。地震震源与先前断层扫描研究中的震源一致，