Mapping of Kedaton Archaeological Sites Using Geomagnetic Methods (Preliminary Study)

Ancient civilizations in Jombang left many historical relics in the form of temples, artifacts, and other archeological sites. Kedaton site is one of the newly discovered archeological sites. This site is buried under a few meters thick of Mount Kelud's pyroclastic flow. Therefore, the distribution patterns of the site is needed to improve the excavation plan in order to maintain the structure of the site. One of the technical approaches that can be applied to map the site's distribution in detail is geophysical survey. Geomagnetic method is a method commonly used in the case of archeological site investigations because of its non-destructive nature. The mapping process on Kedaton site is conducted by applying geomagnetic survey that utilizes physical parameters in the form of magnetic susceptibility. The reduce to pole filter is applied to magnetic data processing to aid interpretation, coupled with horizontal gradient method and analytic signal method further clarify the boundaries of magnetic anomaly sources. Reduce to pole filter indicates that the site's brick detected as moderate to high magnetic anomaly values (more than 450 nT). This research succeeded in mapping clearly the boundaries of the site with an area of up to 6000 meters2 with the shape of the site resembling a building with several chambers. The main chamber is in the north which is the widest chamber, and small chambers are found on the south side.