Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archaeology and Palaeoseismology
TERRESTRIAL LASER SCANNING OF AN ACTIVE FAULT IN GREECE: KAPARELLI
FAULT
T. Wiatr (1), K. Reicherter (1) and I. Papanikolaou (2).
(1) Neotectonics and Natural Hazards, RWTH Aachen. Lochnerstr. 4‐20. 52056 Aachen. GERMANY.
t.wiatr@nug.rwth‐aachen.de, k.reicherter@nug.rwth‐aachen.de
(2) Lab. of Mineralogy & Geology, Department of Sciences, Agricultural University of Athens. 75 Iera Odos Str. 11855 Athens. GREECE.
i.papanikolaou@ucl.ac.uk
Abstract: The terrestrial laser scanner (TLS) has been used for the investigation of escarpments at different sites in Greece. First measurements
have been conducted in spring 2009. In the future, semi‐annual laser scanning will provide the possibility to monitor the fault plane and to
identify the relative ages of the different earthquake events. The data acquisition with the TLS method and the high‐resolution spatial surface
analysis can help to improve data quality, to provide a more accurate prediction. Scientific objectives are the analysis of rock surface
roughness in different scales and types which is of interest to determine relative age of the slip. Furthermore the intensity of reflexivity of the
scarp surface can semi‐automatically help to identify different weathering stages. Additionally, geodetic measurements with compass and GPS
are carried out to cross‐validate the quality of the TLS point cloud data. In this paper we want to present the preliminary results of the
Kaparelli fault (central Greece) obtained the campaign 2009.
Key words: Greece, scarp, Kaparelli fault, LiDAR
INTRODUCTION
During the field kamagne in Greece (April 2009) with the
terrestrial laser scanning system (TLS) the focus was on
the fault escarpments. These are natural exposed surfaces
and give evidence of earthquakes. The concentration lies
on fault scarps in neotectonics active zones in Greece. The
fault plane often extends to the Earth’s surface to
produce ground cracks during earthquakes along the fault
line or the active segment and leaves a distinctive, step‐
like expression in the landscape named fault scarp.
Exhumation of the fault plane due to coseismic slip
exposes the fault surface to differential weathering and
probably to changes in surface roughness. Main aims of
the investigations are to analyze the tectonic
geomorphology and paleoseismology of known active
faults that display post‐glacial fault scarps with ground
based LiDAR system to reconstruct the faulting history
along surface‐rupturing scarps, and to test the potential
of selected locations to calibrate the roughness‐index
method for active faults. The hypothesis of our
investigation on fault scarps shown in Fig. 1 (based on
Benedetti et al. 2002). However, the first step for the
analysis with TLS on this escarpment is to generate a
HRDEM (High Resolution Digital Elevation Model) of the
surface. For our case we need a 3‐D approach to
characterize the different coseismic slip events by the
spatial distribution of the surface roughness from a very
dense 3‐D point cloud data. The spatial resolution should
be in the range of a few millimeters for the following
analysis. The main analytical targets are the roughness
and the backscattered intensity of the escarpment
surface. Primary goals are to characterize slip planes, joint
orientation and spacing, the surface roughness, the dip
directions and orientation and intensity distributions. Tse
and Curden (1979), Kulatilake et al. (1999), Fardin et al.
(2001, 2004), Rahman et al. (2006), Kokkalas er al. (2007a)
169
or Sagy et al. (2007) discussed different approaches for
calculation of the roughness of surfaces.
Fig. 1: Schematic diagram of the evolution of fault scarps and
the related roughness (after Benedetti et al., 2002).
KAPARELLI FAULT
The Kaparelli fault is located in the eastern part of the
Gulf of Corinth (Fig. 2 and 3) and is one of the most
tectonically active regions in Greece (Ganas et al., 2007).
Fig. 2: Geographical overview of Greece and the location of
the Kaparelli investigation area