PROCEEDINGS
Jogja Earthquake in Reflection 2016
24–26 May 2016
Correlation of Geoelectric and the Test Pit to Determine Position of Sliding Surface in the
Prendengan Landslide , Banjarnegara Regency, Central Java Province
Indra Permanajati1, Zufialdi Zakaria2, Euis Tintin Yuningsih2, Herryal Zoelkarnain Anwar3, Eko Bayu
Purwasatriya4, Asmoro Widagdo4
1Doctoral Student at Geological Engineering, Padjadjaran University
1 & 4 Geological Department Jenderal Soedirman University Purwokerto 2 Department of Geology Padjadjaran University, Bandung
3Indonesian Institute of Sciences, Bandung
Abstract
This research aimed to determine the correlation between the
data of geoelectric with test pit to know the position of sliding
surface in Prendengan landslide. Prendengan area is an area that
goes in District Banjarmangu, Banjarnegara regency, Central
Java province. The area is close to the location of Mount
Pawinihan avalanches and avalanche areas Sijembung happened
recently. The area was chosen because of the presence of the
perfect profile associated levels of weathering on the Quaternary
volcanic breccia Rogojembangan (QJo), so
different rock. One target is a homage to the identification of the
type of land movement quickly with considerable intensity. The
method used is the Schlumberger geoelectric method and analysis
of test pit. The results obtained are on a sliding surface weathering
zone 4 with ground material calibration result of weathering of
volcanic breccias. Value resistifitas sliding plane zone is from
153.23 to 1291.27 M Ohm at a depth of 0-396 m. After correlated
with test pit and engineering geological observations along the
sliding surface is got sliding surface occurred in the weathering of
volcanic breccia zone 4 with a depth of ± 8.9 m and shaped sliding
surface is rotational sliding. Identification of the sliding surface on
lithology breccias on the location of the village Prendengan
avalanches can be used as a validation positioning on the sliding
surface breccias in the area of Mount Pawiniahan.
that the geoelectric data correlate with weathering profiles can be
validated properly. This correlation is important to know the
position of sliding surface. Prendengan avalanches in the area and
can be used as a validation of the sliding surface of avalanches in
the area of Mount Pawinihan which is an avalanche by the number
of victims is quite a lot, as many as 80 people died. Identification
of the sliding surface with geoelectric methods need to be
developed in each of the
Keywords : landslide , volcanic breccia , sliding surface ,
rotational sliding , resistivity
Introduction
Landslides are natural process caused by the decline of
material from the top of a hill due to gravity (Varnes, 1978),
this natural phenomenon can be considered dangerous if it
has to interact with human life. Natural disasters avalanches
quite a lot happening in Indonesia, BNPB data (2012) noted
the incidence of avalanches in Indonesia reached 1,000
events with the number of fatalities around 34,000 people
died during the 1815-2012 disaster casualties are frequently
the result is pretty much as it did in avalanches Mount
Pawinihan , Banjarnegara. An avalanche has left an estimated
more than 80 people died (Permanajati et al., 2006). This
phenomenon can not be left unchallenged, to avoid the
number of casualties will be more and more.
Scientist efforts to minimize the impact of disasters can be
done with his research on the mechanism of avalanches. It is
expected to understand the concept of landslide prevention
advice will be sought. From geological studies one of which
discusses the influence of internal land is on the condition of
soil and rock. According Sudarmo and Purnomo (1997) one
of the internal factors that influence soil is rock weathering.
In general weathering is the process of soil formation of
rocks. Expression attempted weathering zone delineated by
the geoelectric and well test equipment on a profile that is a
landslide.
In regional areas of research went into the Quaternary rocks
Rogojembangan composed by breccias. Pyroclastic breccias
in the research area has weathering. The spread of volcanic
breccias almost uniformly in the area of Mount Pawinihan.
This assessment is more focused search for zones where the
sliding plane happens to be the weathering of volcanic
breccias. Correlation between geoelectric and weathering
profiles can be used as a model in deleniasi geoelectric which
have been adapted to the profile of the test wells fresh rock to
soil residues at the very top.
Location of research is in the area of Mount Pawinihan,
Sijeruk Village, District Banjarmangu, Banjarnegara (Figure
1). The research location can be reached by four wheel and
two wheels at the distance of about half an hour from the
town of Banjarnegara to the north. The research location is
the location where the avalanche in the village prendengan
location close to the highway Sijeruk-Prendengan. Landslides
are natural disasters caused by the decline of material from
the top of a hill due to gravity (Varnes, 1978), this natural
phenomenon can be considered dangerous if it has to interact
with human life. Natural disasters avalanches quite a lot
happening in Indonesia, BNPB data (2012) noted the
incidence of avalanches in Indonesia reached 1,000 events
with the number of fatalities around 34,000 people died
during the 1815-2012 disaster casualties are frequently the
result is pretty much as it did in avalanches Mount Pawinihan
Banjarnegara. An avalanche has left an estimated more than
PROCEEDINGS
Jogja Earthquake in Reflection 2016
24–26 May 2016
80 people died (Permanajati et al., 2006). This phenomenon
can not be left unchallenged, sehngga the number of
casualties will be more and more.
Man's efforts to minimize the impact of disasters can be done
with his research on the mechanism of avalanches. It is
expected to understand the concept of landslide prevention
advice will be sought. From geological studies one of which
discusses the influence of internal land is on the condition of
soil and rock. According Sudarmo and Purnomo (1997) one
of the internal factors that influence soil is rock weathering.
In general weathering is the process of soil formation of
rocks. Expression attempted weathering zone delineated by
the geoelectric and well test equipment on a profile that is a
landslide.
In regional areas of research went into the Quaternary rocks
Rogojembangan composed by breccia lithology piroklasik.
Pyroclastic breccias in the research area has weathering. The
spread of volcanic breccias almost uniformly in the area of
Mount Pawinihan. This assessment is more focused search
for zones where the sliding plane happens to be the
weathering of volcanic breccias. Correlation between
geoelectric and weathering profiles can be used as a model in
deleniasi geoelectric which have been adapted to the profile
of the test wells fresh rock to soil residues at the very top.
Location of research is in the area of Mount Pawinihan,
Sijeruk Village, District Banjarmangu, Banjarnegara (Figure
1). The research location can be reached by four wheel and
two wheels at the distance of about half an hour from the
town of Banjarnegara to the north. The research location is
the location where the avalanche in the village prendengan
location close to the highway Sijeruk-Prendengan.
Methodology
The study was conducted in the following order. The first to
do is to classify the level of weathering by the method of
British Standard BS EN ISO 14689-1 for the material is not
uniform (Source: Price, 2009) at the location of avalanches.
This classification to divide zones of weathering. Then
conduct geoelectric the avalanche cut him so diharakan soil
profile on location avalanches can be observed well. Next to
the correlation determines the position of sliding plane.
Table 1. Classification of degree of weathering by British
Standard BS EN ISO 14689-1 for the heterogen material
(Source: Price, 2009)
Results and Discussion
The location is in the Prendengan landslide with coordinates:
07 ° 18 '41.7 ", 109 ° 41' 52.4". The locations were right lane-
Prendengan Sijeruk of Banjarnegara. Based on the
weathering profile measurement obtained the degree of
weathering of rock is 2 to 6. The pyroclastic breccias
Figure 2. The observation of the soil profile at the location of
the Prendengan landslide
Research area
Figure 1. Map of research area
PROCEEDINGS
Jogja Earthquake in Reflection 2016
24–26 May 2016
Based on observations in the field, is the result of breccia
formed in volcanic activity, which is a product of pyroclastic
fall. It is characterized by grain and uniformity has sorting
either the large grains are graded (gradded bedding).
According to Lockwood and Hazlett (2010) declared the
formation of pyroclastic breccia with a uniform grading
showed formed as pyroclastic activity dropping, then changes
the gradation on pyroclastic breccias in the field fining
upward showing a decline in volcanic activity (Figure 3).
Based on the measurement results obtained geoelectric soil
profile and distribution of soil and rock (Figure 4). Land
obtained at a depth of 0 to 3.96 m, and then beneath the
breccia with a depth of 3.96 to 6.9 m, then 6.9 m - 62.82 m
are sandstones, silty sandstones further below and clay.
Figure 3. Profile weathering of pyroclastic breccias in the
village of Prendengan show structure of gradded bedding.
Figure 4. Figure geoelectric log results in Prendengan
landslide
Based on the results of correlation of test wells and
geoelectric and validation sliding plane can be obtained
through sliding plane are at a depth of 8.9 m based on
measurements of the soil profile and there is a limit on the
degree of weathering 3 and 4, and based on the data of
geoelectric there is a layer of sandstone. So from the
geoelectric observations contained in some layers of
sandstone. It is clear that for this kind of observation with
geoelectric avalanches in the breccia is not easy but it needs
to be supported by the observation of the weathering profile
and approach the degree of weathering. Avalanche of events
in Prendengan can be concluded that there is a sliding plane
on weathering boundaries 3 and 4
Conclusion
There sliding surface at a depth of 8.9 m, which are at the
limit of weathering weathering 3 and 4. Level 3 is
characterized byTheir composition fragments that still shows
the composition of rocks compared to the matrix. Then the
rate of weathering 4 is characterized by the presence of
fragments, but the fragility of the material matrix of control.
The weathering rate limit is often difficult because of the
differences observed with geoelectric boundaries of
weathering is graded material.
Slip Surface
Slip surface
PROCEEDINGS
Jogja Earthquake in Reflection 2016
24–26 May 2016
Reference
BNPB.(2012): Data Informasi Bencana Indonesia,
http://www.bnpb.go.id/website/asp/index.asp,
diunduh tanggal 20 Juli 2012
Lockwood, J.P and Hazlett, R.W. (2010): Volcanoes Global
Perspective, John Wiley & Sons Ltd, The
Atrium, Southern Gate, Chichester, West Sussex,
PO19 8SQ, UK.
Permanajati, I., Waluyo,G., Suwardi., dan Setijadi, R.,
(2006): Longsoran Gunung Pawinihan, Desa
Sijeruk, Kecamatan Banjarmangu, Banjarnegara,
Prosiding Lokakarya DAS Serayu Hulu, Unsoed,
pp. 1-4.
Soedarmo, G.D. dan Purnomo, S. J. (1997): Mekanika Tanah
2, Kanisius, Yogyakarta.
Varnes, D.J. (1978): Slope Movement Type and Processes in
Landslide Analysis and Control, Trasportation
Research Board, National Academy of Science.
Top Related