Modeling how a Powerful Airburst destroyed Tall el-Hammam, a Middle Bronze Age city near the Dead Sea

Abstract

A previous study presented evidence supporting the hypothesis that a low-altitude airburst approximately 3600 years ago destroyed Tall el-Hammam, a Middle-Bronze-Age city northeast of the Dead Sea in modern-day Jordan. The evidence supporting this hypothesis includes a widespread charcoal-and-ash-rich terminal destruction layer containing shock-fractured quartz, shattered and melted pottery, melted mudbricks and building plaster, microspherules, charcoal and soot, and melted grains of platinum, iridium, nickel, zircon, chromite, and quartz. Here, we report further evidence supporting a cosmic airburst event at Tall el-Hammam. Fifteen years of excavations across the city revealed a consistent directionality among scattered potsherds from individually decorated vessels, including one potsherd group distributed laterally approximately southwest to northeast across ∼22 m, spanning six palace walls. Similar trails of charred grains, charcoal, and bone fragments were also found distributed across multi-meter distances inside the destroyed city. Although an earlier report of the directionality of this debris was challenged, further evidence presented here strengthens that interpretation. We also report Middle-Bronze-Age partially melted breccia that likely formed at >2230 °C, consistent with a cosmic event. We investigated additional glass-filled fractured quartz grains using ten analytical techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), cathodoluminescence (CL), and electron backscatter diffraction (EBSD). These grains are inferred to have formed by high-pressure shock metamorphism, consistent with an earlier report that has been challenged. To test that the mode of destruction could have been an airburst, we produced a hydrocode computer model of a Type 2 or touch-down airburst, in which a high-temperature, high-pressure, high-velocity jet intersects Earth’s surface, producing meltglass, microspherules, and shock metamorphism. The modeling shows that the explosive energy released can propel high-velocity airburst fragments to strike the Earth’s surface, producing shock metamorphism and creating superficial craters potentially susceptible to geologically rapid erosion. Although the probability of such airbursts is low, the potential for substantial damage is high, especially in cities.