Last field campaign in Christoph's Guatemala project
The western end of the Motagua Fault was the target of a field campaign in Christoph Grützner's DFG-funded Guatemala project.
Excavation of a paleoseismological trench in Guatemala
Published:
The Motagua Fault and the 1976 earthquake
Geophysical prospection of the fault zone to chose the best trench site
Image: Christoph GrütznerA major earthquake in 1976 caused a surface rupture of more than 230 km along the Motagua Fault. This fault is part of the plate boundary between the North American and Caribbean plates in Guatemala. Previous field campaigns in Christoph's DFG-funded project targeted the centre of the fault and successfully identified and dated five major earthquakes in the last 1300 yearsExternal link. The most recent campaign in January 2026 led to the western end of the fault. There, an international team led by Christoph Grützner and Tina Niemi (University of Missouri – Kansas City) aimed to determine whether the now-known earthquakes also reached the western end of the fault. This will allow for better estimations of earthquake magnitude and fundamental insights into fault behavior during large earthquakes.
Geophysics and paleoseismology
Drone image of the paleoseismic trench near Pachalum, Guatemala
Image: Christoph GrütznerTo find out, geophysical investigations were conducted first. Using four-point geoelectrics, led by Christoph's colleagues from Missouri, the subsurface structure near Pachalum was examined. There, the surface rupture of the fault ended in 1976. A high-resolution digital elevation model was created using drone photographs and a LiDAR drone. Based on these results, a paleoseismological trench was then excavated across the fault zone. At least three earthquakes were identified within this trench; radiocarbon dating of charcoal samples is still pending.
Other targets of the field campaign included the archaeological sites of Mixco Viejo and Vega de Coban, both damaged in 1976, as well as Tikal. Further work was also carried out on the Motagua Fault near Sanarate and Estanzuela. Student Rupert Hauschild accompanied Christoph on this campaign and will analyze the geophysical and paleoseismological data for his bachelor's thesis.
Following the field campaign, Christoph led an international excursion group along the plate boundary as part of the PATA Days conference. A report on this can be found hereExternal link(in English).
Many thanks to Omar Flores and Luís Romero (Universidad San Carlos de Guatemala) and the landowners who granted us access to their properties, as well as to all participants of the Guatemala GeoHazard projectExternal link.