Archaeoseismological study of the Cherichira aqueduct bridge, Kairouan, Tunisia

In the past, several destructive earthquakes have occurred in the North African Atlas Mountain ranges located along the Africa–Eurasia plate boundary. Although the region is rich with impressive archaeological sites, including those in modern Tunisia, few comprehensive archaeoseismological studies have been conducted. Historic sources account at least three damaging earthquakes in the Kairouan area in central Tunisia between AD 859 and 1041. Little is known about which faults triggered these earthquakes or the size of these events. The water supply of the city of Kairouan depended on a 32-km-long aqueduct with a large bridge (now partially collapsed) at the confluence of the de Mouta and Cherichira rivers. The original bridge of Roman construction was retrofitted twice during the Aghlabid period (AD 800–903) and probably in AD 995 during the Fatimid period. The ruined section of the bridge shows damage which might be related to the AD 859 earthquake shaking. Here, we present a detailed study of the history, the status and the damage of the Cherichira aqueduct bridge using previous historic accounts and written works, a 3D laser scan model, local geological and seismological characteristics, and include results of radiocarbon dating and a timeline of events. In addition to earthquake ground motions, we consider severe flash floods on the bridge as a potential cause of the damage. We estimate the severity of such flash floods and develop a model with 18 earthquake scenarios on local reverse and strike-slip faults with magnitudes between MW 6.1 and 7.2. While a few damage patterns might be indicative of flooding, most damage can be attributed to earthquakes. It is highly probable that the earthquake in AD 859 caused enough damage to the Aghlabid bridge to render it dysfunctional; however, to resolve the question of whether another earthquake in AD 911 or 1041 caused the complete destruction of the previously retrofitted aqueduct by the Fatimids requires dating of additional sections of the bridge.

Stacking Rocks to Transport Water: Folk Aqueduct Bridges of Mallorca and Spanish Colonial California

The landscape of Mallorca, Spain is characterized by a number of features constructed of rock. Windmills and walls are ubiquitous and visually striking. Equally widespread, but not as conspicuous, are other features associated with canal irrigation. One such feature that is understudied and therefore underappreciated is that of folk aqueduct bridges. This study investigates these features because they were critical in sustaining agriculture on the island for centuries, because they deserve recognition in order to be preserved as part of the island’s cultural and historical heritage, and because of their being antecedents or prototypes of similar structures built in Spanish colonial California. Two field seasons were devoted to locating and studying folk aqueduct bridges. Systematic windshield surveys were undertaken to identify such features. Once located, each folk aqueduct bridge was subjected to detailed description and analysis of size, shape, function, materials, and method of construction. Folk aqueduct bridges of Mallorca were built of shaped and unshaped stone, with channels made of ceramic tiles or ashlar tablets. Many of the rock walls once served as folk aqueduct bridges. Several California missionaries in the 18th century came from Mallorca, and the folk aqueduct bridges they built are based on those of their homeland.

Fluid Modeling for Seismic Analyses of Aqueduct Bridges

The aqueduct bridge carries a large amount of water (fluid). How to model fluid is a basic issue in the seismic analysis and design of aqueduct bridges. This paper discusses and summarizes computational methods of fluid for the three-dimensional seismic response analyses. The result of this paper provides a reference for the researchers and engineers, who are interested in seismic-resistance computations of aqueduct bridges.