The AD 260 Eruption at Lake Ilopango, El Salvador: A Complex Explosive Eruption Through a Caldera Lake

公元 260 年萨尔瓦多伊洛潘戈湖喷发：穿过火山口湖的复杂爆炸性喷发

• 批准号: 9903291
• 负责人: James Vallance
• 金额: $ 16.02万
• 依托单位: Michigan Technological University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-15 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9903291&HistoricalAwards=false
• 关键词: AD; 260; Eruption; Lake; Ilopango

9903291VallanceIlopango caldera in central El Salvador erupted violently to produce widespread ashfalls and hot ash flows at least four times in the last 60,000 years, and most recently in AD 260. Ilopango is perhaps the most dangerous volcanic center in Central America because of its potential for violent explosive eruption and its proximity to San Salvador, the largest city in Central America. In AD 260, hot ash flows spread throughout the Salvadoran highlands and swept up to 40 km down steep valleys onto the Pacific coastal plain, areas then populated by early Mayan civilization and now densely populated. Ash fell across much of Central America, much of southern Mexico, and nearby parts of the Pacific Ocean and Gulf of Mexico. The eruption may well have been the greatest catastrophe ever to befall Meso-American civilization. The eruptives have total volume of 20 to 50 cubic km and encompass 6 stages: (1) initial fall and surges, (2) main Plinian fall, (3) energetic pyroclastic deposit, (4) phreatoplinian fall, (5) bedded phreatomagmatic fall, and (6) main ignimbrite. This study will characterize controls on eruption style and intensity and differentiate factors intrinsic and extrinsic to the magma. Study of the complex but distinctive stratigraphy of deposits will address the following important topics in volcanology: field calibration of numerical models for Plinian eruptions, transport and deposition mechanisms for pyroclastic flows and surges, and magma-water interactions in explosive eruptions through shallow water. The chief goal of the study is a better understanding of the behavior of explosive eruptions through shallow water and, specifically, that of Ilopango caldera during eruptive cycles. An important secondary goal is increasing awareness of volcanic processes and their affiliated hazards in El Salvador.

9903291位于萨尔瓦多中部萨尔瓦多的瓦伦斯伊洛潘戈火山口在过去的6万年里至少爆发了4次，最近一次是在公元260年。 伊洛潘戈可能是中美洲最危险的火山中心，因为它有可能发生剧烈的爆炸性喷发，而且靠近中美洲最大的城市圣萨尔瓦多。 在公元260年，热灰流蔓延到整个萨尔瓦多高地，并沿着陡峭的山谷席卷了40公里，进入太平洋沿岸平原，这些地区当时居住着早期玛雅文明，现在人口稠密。 火山灰落在中美洲大部分地区、墨西哥南部大部分地区、太平洋和墨西哥湾附近地区。 这次火山爆发很可能是中美洲文明有史以来最大的灾难。 火山喷发物的总体积为20 ~ 50立方km，可分为6个阶段：（1）初始降落和涌浪，（2）主要普林尼式降落，（3）高能火山碎屑存款，（4）潜水普林尼式降落，（5）层状潜水岩浆降落，（6）主要熔结凝灰岩。 本研究将描述喷发方式和强度的控制因素，并区分岩浆的内在和外在因素。 对复杂但独特的矿床地层学的研究将涉及火山学中的以下重要课题：普林尼式喷发的数值模型的实地校准、火山碎屑流和浪涌的运输和沉积机制以及浅水爆炸性喷发中的岩浆-水相互作用。 这项研究的主要目标是更好地了解浅水爆炸性喷发的行为，特别是伊洛潘戈破火山口在喷发周期中的行为。 一个重要的次要目标是提高对萨尔瓦多火山过程及其相关危害的认识。