Proceedings of the International Symposium on Engineering Lessons Learned fromthe 2011 Great East Japan Earthquake, March 1-4, 2012, Tokyo, JapanCOMPARING LIQUEFACTION PHENOMENAOBSERVED DURING THE 2010 MAULE, CHILE
EARTHQUAKE AND 2011 GREAT EAST JAPAN
EARTHQUAKE
Ramón VERDUGO1
1

Principal, CMGI Ltda. Santiago, Chile
rverdugo@cmgi.cl

ABSTRACT: On February 27, 2010, the central-south part of Chile was affected by astrong ground motion of Magnitude 8.8, that induced moderate values of peak groundacceleration (PGA) on rock outcrops, in the range of 0.13g to 0.32g, while in soil
deposits, a maximum PGA of 0.94g was recorded. The duration of the shaking was close
to two minutes as it is substantiated by the available acceleration records. A significant
number of sites experienced the phenomenon of liquefaction, causing failures of houses,
buildings, bridges, routes, ports, railways, buried structures and tailings dams. Likewise,
widely spread soil liquefaction was also observed during the 2011 Great East Japan
Earthquake. The ground motions of this earthquake and the subsequent aftershocks also
had long duration. In this paper, the effects of durations of seismic shaking on theliquefaction-induced damages are highlighted, and compared between the 2010 Chile
earthquake and the 2011 Japan earthquake. Especially, the damages induced byliquefaction observed in bridges and ports in Chile are presented and analyzed.
Additionally, several cases of lateral spreading observed along rivers and lakes arepresented.
Key Words: Maule Chile earthquake, Great East Japan earthquake, Liquefaction.

INTRODUCTION
A mega earthquake of Magnitude 8.8 occurred in the South-Central part of Chile on February 27, 2010,at 3:34 a.m. local time. A significant number of aftershocks followed the initial quake. The mostimportant, Magnitude 6.2, occurred 20 minutes after the main shock (USGS, 2012). The earthquake
triggered a tsunami that struck off the Chilean coast, devastating towns located onshore, causing
additional deaths and widespread damages. The 2010 Maule Chile earthquake is associated with thesubductive seismic environment generated by the collision between the Nazca and the South American
tectonic plates, which are converging at an estimated rate of 65 to 80 mm per year. The Nazca plate is
subducting under the South American plate, moving down and landward. The Maule Earthquake has
been identified as a thrust-faulting type that occurred on the interface between these two plates, at an
average depth of 30 km. The rupture zone involved in this earthquake can be observed in Fig. 1, which707

dimensions cover a rectangular area of approximately 450 km by 170 km. The earthquake together
with the tsunami caused near 600 casualties and an estimated economic loss of 30 billion US dollars.
On Friday, 11 March 2011, at 14:46 local time, a mega earthquake of Magnitude 9.0 hit the northeast
coast of Honshu, Japan. After a few minutes a series of large aftershocks of Magnitudes of 7.4, 6.4, 6.1,
7.4 and 7.2 struck the area at 15:09, 15:06, 15:13, 15:15 and 15:26, respectively (K-Net, 2012). The
main shake was followed, approximately after 20 minutes, by a huge tsunami that destroyed many
cities along the Pacific coast. This earthquake, known as the 2011 Tohoku earthquake, or the Great
East Japan Earthquake, resulted from thrust faulting on, or near, the subduction zone plate boundary
between the Pacific and North America plates. In the area of the earthquake, the Pacific plate moves
approximately westwards with respect to the North America plate, at a rate of around 80 mm per year.
Models of the rupture zone indicate that the fault moved upwards around 40 m, and slipped over an
area approximately of 500 km long by 200 km wide (Fig. 1). The rupture zone is roughly centered on
the earthquake epicenter along-strike. This strong ground motion left more than 15 thousands people
dead, and even more imperiled, and an estimated total economic loss of 300 billion US dollars.

Fig. 1.- Rupture zones associated with Maule (USGS) and Tohoku (Ammon et al, 2011) earthquakes
As can be observed, strong earthquakes with magnitudes above 8.5 develop huge areas of rupture,compromising hundreds of kilometers, with the corresponding generation of seismic waves. Therefore,
the usual characterization of the epicenter by a single point does not represent the actual phenomenonof seismic energy generation-propagation. Consequently, the distance from the site to the epicenter is
not a good parameter to characterize the seismic attenuation, or seismic intensity, which should
correlate with other parameters; for instance, the distance to the “fault trace”. This corresponds to thelocus at the surface of the vertical projections of the most probable rupture initiation. In other words,
the fault trace represents a sort of mobile epicenter. Accordingly, the distance to the classical epicenteris intentionally avoided in this paper.
Both mega earthquakes, with their tsunamis, were extremely destructive demanding the maximum
resilience of the community to recover the sense of an organized life. From a geotechnical engineering
perspective, both earthquakes have shown that one of the most important causes of catastrophic
failures in any kind of structure is associated with the phenomenon of liquefaction. Remarkableevidence of this phenomenon is presented and discussed, along with the main factors that control it.

708

SHAKING DURATION AND LEVEL OF STRESSESIn the case of Maule earthquake, the peak accelerations recorded on rock outcrop and soil deposits arepresented in Figs. 2 and 3, respectively. It is interesting to observe that PGA recorded on rock outcrop
are surprisingly moderate, not exceeding 0.32g for any of the available recorded values. Nevertheless,in the coast line, immediately in front of the epicentral zone, there were no instruments to record theacceleration histories, and therefore, it is possible for this area to presume the occurrence of higher
PGA than the ones reported. On the other hand, higher values of PGA were recorded on soil deposits,
being the maximum 0.94g recorded in the city of Angol.

Fig. 2.- PGA recorded on rock outcrops
Maule 2010 Chile Earthquake

Fig. 3.- PGA recorded on soil deposits
Maule 2010 Chile Earthquake

The acceleration time histories recorded on rock outcrop in Santa Lucia hill, located in Santiago(capital city of Chile), and their response spectra are presented in Fig. 4. It can be observed that therock outcrop shaking shows a broad band of frequencies, in the range of 1 to 10 Hz (period of 1 to 0.1
sec). Additionally, the total duration of the quake is close to 2 minutes. The N-S component of threerecords obtained in different soil deposits are shown in Fig 5. It is important to mention that the total
duration of the recorded motions is also more than 2 minutes, which is a long time of continuous
vibration being applied to the existing saturated sandy soil deposits and it may explain the widely
spread soil liquefaction observed during the Maule Earthquake.
Due to an enormous effort after the Kobe Earthquake, Japan has been able to implement a dense arrayof seismic stations for strong motions, which are well distributed throughout the country. Therefore,
the 2011 Tohoku earthquake was well monitored. The data indicate that there are two sites where the
PGA’s were extremely high: 2.93g and 2.7g recorded at Tsukidate and Miyagi prefecture, respectively.
In Tokyo, a PGA of 0.5g was recorded. According to the available information, the high acceleration
observed at Tsukidate comes from a single pulse of high frequency, being the damage of the structures
not significant. This confirms the empirical observation regarding the poor correlation between PGA
with structural damage.
The N-S components of acceleration records obtained at Kashima, Sawara and Urayasu are shown in
Fig. 6. These records were obtained in areas where liquefaction was clearly observed. From these709

records, it is possible to indicate that the seismic shaking continued for more than 2 minutes, withrelatively large accelerations. In addition, between 20 to 40 minutes after the main shock, five large
aftershocks struck the region. Therefore, for a quite significant interval of time, the existing saturated
sandy soil deposits were subjected to seismic vibrations, which can be expected to be an importantfactor for inducing liquefaction.

Fig. 4.- Acceleration histories and response spectra. Rock outcrop at Santa Lucia Hill, Santiago, Chile

Fig. 5.- N-S acceleration records at three sites
Maule 2010 Chile Earthquake (Renadic)

Fig. 6.- N-S acceleration records at three sites
Kohoku 2011 Japan Earthquake (KiK-net)

The previous large earthquake that struck the Central part of Chile occurred on March 3, 1985.
According to the geotechnical reports of that time, this earthquake, of Magnitude 7.8, did not induceliquefaction. The maximum horizontal accelerations were recorded in Melipilla city (approximately 60
km to the South-West of Santiago and 85 km to the South-East of Valparaiso). The N-S and E-W
components were 0.67g and 0.60g, respectively. Therefore, the area around Melipilla has been
subjected to similar level of shaking, in terms of acceleration, during both 1985 and 2010 earthquakes.
It is important to understand that Melipilla city was significantly close to the epicenter area during
1985 earthquake (M= 7.8). On the contrary, for the 2010 earthquake (M=8.8) it was rather far. Both710

horizontal components recorded at Quintay and Zapallar during the 1985 Chile Earthquake are shownin Fig. 7. These sites are on the epicentral area. It can be observed that the total duration of theseacceleration time histories is around 70 seconds, considerably shorter than the length of the records
obtained from the 2010 Chile (120 sec) and 2011 Japan (150 sec) earthquakes.

Fig. 7.- Acceleration records of Quintay and Zapallar, 1985 Chile Earthquake
Considering that almost no liquefaction was reported after the 1985 earthquake, it is postulated that theoccurrence of liquefaction on the field is mainly controlled by the duration of the seismic load,
followed by the level of cyclic stresses. This hypothesis will be supported with field observation
presented below.
AREA AFFECTED BY LIQUEFACTION DURING 2010 CHILE EARTHQUAKE
Combining the damage reported in the extensive work performed by Astroza and collaborators (Ruizand Astroza, 2012), with the infrastructure damage reported by the Ministry of Public Work, a map ofintensity was elaborated, which is presented in Fig. 8. It is observed some irregularities in theisoseismals that reflect local site effects. The higher intensity (greater than VIII) are concentrated inthree areas: the town of Navidad, the coastal area from Pichilemu to Constitution, entering the central
valley in the towns of Santa Cruz and Talca, and the central depression in the towns of Cauquenes andParral.
Regarding the occurrence of liquefaction, field observations have highlighted that the Maule 2010
Chile earthquake triggered liquefaction in more than 100 sites (Fig. 9). The northernmost site withevidence of liquefaction, corresponds to the limited slope instability experienced by the downstream
slope of the tailings dam Veta del Agua, located approximately 13 km north-east of La Calera. Whilesouthernmost liquefaction occurred in Calafquén and Panguipulli lakes, located around 250 km to thesouth of the rupture zone. Consequently, the area with evidence of liquefaction covers a north-south
distance of about 800 km, which corresponds to an area of almost twice the rupture zone.
It is observed that liquefaction sites cover an extensive area to the south of the rupture zone, which ismuch reduced to the north of the rupture zone. This fact could be explained by the limited existence of
saturated sandy soils deposits to the north of Santiago, while saturated sandy soils are more common
to the south of Concepcion, especially on the banks of rivers and lakes. The areas that showed moresites affected by liquefaction are in Concepción, Retiro – Parral and Paine (south of Santiago).

711

It is remarkable the fact that liquefied sites were observed in areas where the intensity was less than V.
For example, the lateral spreading that involved banks of Lake Calafquén in the south (Fig. 10). The
description of witnesses at Pucura sector (kilometer 10 of route Coñaripe - Lican Ray) states: "We had
a family of gypsies who were camping on the site when the shaking started, they shouted calling us, aonce we got over there the water come out of the earth as a hose stream "(website of the Panguipulli
City Hall).This necessarily implies that the intensity of the quake, which correlates directly withstructural damages, is not completely associated with the occurrence of liquefaction. Although thisconfirms the well-known dependence of the liquefaction strength on both level of cyclic stresses andnumber of cycles, it also shows the actual impact of the earthquake duration on the liquefaction
strength.

Fig. 8.- Intensity map, 2010 Chile Earthquake

Fig. 9.- Sites where liquefied was observed
during 2010 Chile Earthquake

Fig. 10.- Lateral Spreading observed in an area of low intensity: Pocura and Calafquen(source: Sernageomin and Municipalidad of Panguipulli)712

LIQUEFACTION OF FLAT GROUND
The site inspection identified clear evidence of liquefaction in areas practically horizontal or with very
gentle slopes. The most relevant cases took place in Concepción, Retiro - Parral, Arauco, Paine, Las
Cabras and Nancagua. In Concepcion and surrounding areas, evidence of liquefaction was observed in
the following sites: Sub Power Station Cementos Bio Bio, Brisas del Sol Condominium, The
Presidents Condominium, Buena Vista Village, Villa CAP, Park Residential Collao and Bayonne.
Additionally, liquefaction occurred also in Arauco City, in two wastewater lifting plants: Cochrane andEduardo Frei.
One example is the case of Brisas del Sol Condominium, located in Talcahuano, where 5 houses
located in front of a wetland (similar to a swamp) suffered lateral displacement up to 2 meters. One of
the houses is shown in Fig. 11. Another case occurred near the City of Concepcion, where the railway
collapsed in several places due to liquefaction and subsequent settlements, as shown Fig. 11.

Fig. 11.- Liquefaction of flat areas. Condominium Brisas del Sol and railway near Concepción (EFE)
LATERAL SPREADING
Lateral spreading is probably the most recurrent phenomenon observed after earthquakes on sloping
ground, adjacent to river banks or lakes. Numerous cases of lateral spreading occurred along the rivers
Nilahue, Mataquito, Itata, BioBio, Carampangue and Lebu. In some cases the cracks involved several
kilometers along the river banks. Also, lakes were affected by lateral spreading: Laguna Aculeo, Rapel,
Vichuquén, Calafquén, Panguipulli, and the main lagoons in Concepción. The sites where thephenomenon of lateral spreading occurred along the Lebu River are identified in Fig. 12.

Fig. 12.- Lateral spreading observed along the Lebu River. Maule 2010 Chile Earthquake

713

The large number of sites that were affected by lateral spreading corroborates that this is probably themost characteristic phenomenon associated with liquefaction failure.
From Fig. 13, it is possible to quantify the potential effect of lateral displacements and settlements. In
this case, different sites along the northern bank of Bio Bio River collapsed deforming toward theriver.

Fig. 13.- Cracks and settlements on right side of BioBio River caused by lateral spreading
LIQUEFACTION OF TAILINGS DAMS
The experience from observations in highly seismic regions shows that tailings dams are sensitive toearthquakes; in fact, several seismic failures have been reported throughout the years. However, mostof these seismic failures have been described in tailings dams constructed under upstream method. It is
worth to mention that properly designed tailings dams constructed using downstream or center-line
methods have shown to be seismically stable. In Chile, where the seismicity is high and the mining
industry is active, thousands of tailings dams are distributed throughout the territory, and several ofthem constructed by the upstream method have experienced failure due to liquefaction.
After the 2010 Chile earthquake five tailings dams constructed by the upstream method were reportedwith different levels of seismic failure: Chancón, Bellavista Dike No. 1, Veta del Agua Dike No. 5,
Alhué and Las Palmas (Ramirez, 2010). Bellavista Dike No.1 collapsed, and a significant volume oftailings flowed into the Dike No. 2, which worked as a buffer, stopping the tailings flow. Dike No. 5 ofVeta del Agua experienced a limited seismic failure; the toe of the dike moved down for a distance of
100 m, reaching El Sauce creek. Las Palmas experienced a catastrophic failure triggered by the 2010
Chile earthquake. The geometries before and after the failure are shown in Fig. 14 (Bray et al, 2011).

Upper Dike
Lower Dikel

Fig. 14.- Pre-earthquake and post-earthquake satellite images of Las Palmas tailings dam

714

The tailings liquefied, flowing for a distance of about 0.5 km, killing four people who lived in a housethat was buried under 4 m of tailings. The tailings dam consisted of two dikes (a lower one and an
upper one), constructed in stages using the upstream construction method. This dam was operating
until 1997, when the mining activity finished. From field observations it has been deduced that thebottom of this tailings dam was saturated, triggering a flow failure.
BRIDGES AND OVERPASSES AFFECTED BY LIQUEFACTION
According to all the information that has been collected and analyzed, 12 bridges and 4 overpasses
were damaged by ground failure associated with liquefaction of ground foundations or accesses.
Bridges affected by liquefaction of soil foundation were Andalién, Juan Pablo II, La Mochita, Niagara,
Ramadillas, Raqui II, San Nicolas, Tubul and Yali I. Bridges with ground failure at the accesses were
Alhue, El Durazno and Llacolén. Additionally, there were signs of liquefaction (settlements and sandboils) of the natural soil at Mataquito Bridge, which was not affected because the liquefiable soil was
not used to support the structure. On the other hand, overpasses affected by the phenomenon ofliquefaction were: Chada, Champa, Hospital and Los Pinos.
The location of these bridges and overpasses is shown in Fig. 15. It can be observed that there are twoareas where there is a concentration of liquefaction phenomena. Failure of bridges is moreconcentrated in the Concepción area, whereas failure of overpasses is clearly observed to beconcentrated to the south of Paine area, as shown in Fig. 16, where three additional sites liquefied.

Fig. 15.- Bridges and overpasses affectedby liquefaction

Fig. 16.- Concentration of liquefaction in Paine area

The bridge Juan Pablo II, located at the BioBio River, was the most seriously affected by thephenomenon of liquefaction. After the quake significant differential settlement showed up along thedeck and the first pier (Concepcion abutment) collapsed due to the loads generated by lateral
spreading (Fig. 17).
The topographic information obtained along both lines of the bridge allowed the assessment of thevertical deformation developed along the bridge. The result is presented in Fig. 18; around 15 piersdeveloped settlements higher than 50 cm. In general, supports of the left longitudinal axis (upstream)715

developed greater settlements than those observed in the right longitudinal axis. Larger settlements areconcentrated at the Concepción abutment bank. The largest settlement is approximately 1.8 m,
followed by settlements of 1.1 m and 0.9 m.

Fig. 17.- Settlement caused by liquefaction, and failure due to lateral spreading.
Juan Pablo II Bridge affected by 2010 Chile Earthquake

Fig. 18- Post-seismic settlements, Juan Pablo II Bridge
Because of the large differential settlements suffered by the piers, Juan Pablo Bridge was closed, and aseries of 16 boreholes with N-SPT measurements was carried out by the Ministry of Public Works.
Additionally, a limited number of classification tests were performed. The results are shown in Fig. 19,
in terms of the normalized N1-SPT (normalized to 1 kg/cm2) and the fines content.
The most interesting aspect of this case is associated with the fact that only vertical permanent
displacements were developed. The absence of lateral displacements necessarily implies that there arelayers of non-liquefiable soils that were able to develop sufficient lateral stiffness to stabilize thestructure. The N1-SPT confirms the existence of a highly stratified ground deposit, consisting of loose
to dense sands and soft sandy silts. It is estimated that values of standard penetration tests (N 1)60,
exceeding 30 blows/foot are associated with layers of dense soil that should be responsible for the
existence of enough lateral stiffness to prevent horizontal displacement.
It is important to indicate that, due to geological and tectonic issues, in Chile it is possible theoccurrence of highly stratified soil deposits, where may coexist loose and dense sandy soils, with soft
silts. As a consequence of this, the strength and deformability may be significantly different in bothvertical and horizontal direction. This is the case of the ground that supports Juan Pablo II Bridge.

716

Fig. 19.- N1-SPT, results obtained in Juan Pablo II Bridge
OBSERVED LIQUEFACTION IN PORTS AND DOCKS
Ports and quays were also affected by liquefaction of the coastline and the seabed. The most severecases of failure occurred between Talcahuano and Lota, specifically in the La Poza (Talcahuano), Lo
Rojas (Coronel), Lota Bajo (Lota) and the Port of Coronel areas. In addition, some industrial facilities
located in Coronel also suffered the effects of liquefaction. Part of the damages observed in thesecoastal structures is shown in Fig. 20.
The liquefaction of the line shore soil, in addition to the inclination of the ground toward the sea,
generated a lateral flow which dragged the piles. However, the end part of the docks was supported by
non-liquefiable soils that prevented any horizontal displacement. Thus the piles kept the head in place,
fixed by the supra-structure, but their bottoms moved toward the sea following the direction of theflow of the liquefied soil.

Fig. 20.- Damages observed in private infrastructure and Port of Coronel

717

LIQUEFACTION BY THE 2011 GREAT EAST JAPANThe 2011 Tohoku Earthquake caused severe liquefaction in reclaimed lands. Tokyo Bay, including
areas in Urayasu and Chiba City developed extensive liquefaction. Areas along the lower stream ofTonegawa River also liquefied, including sites in Katori of Chiba Prefecture and Itako City, Kamisu
City and Kashima City of Ibaraki Prefecture (Tsukamoto et al, 2012; Tsukamoto et al, 2012).
Reclaimed lands that liquefied were constructed back in the 60´s, using soils dredged from the bottomof the bay. However, reclaimed lands that were improved by different techniques did not liquefy.
Considering the vast extension of the reclaimed land, thousands of residential houses and buildings
were affected by liquefaction, inducing settlement and tilt. Therefore, the most important liquefaction
occurred in man-made fills.

CONCLUSIONSThe 2010 Chile Earthquake (M=8.8) induced liquefaction in more than 100 sites constituted by naturalsoil deposits and some man-made fills, covering an extensive area, being the largest distance in thenorth-south direction, of about 800 km. However, a previous earthquake that struck the central part ofChile in 1985 (M=7.8) did not trigger liquefaction. Although in both earthquakes, similar levels of
accelerations were recorded in some areas, the 2010 Earthquake triggered liquefaction and the 1985
did not. Therefore, it is confirmed that the duration of the shaking is a key element that made thedifference between those sites which presented liquefaction, from those that did not liquefy. This is awell-known fact, but it seems to be more important than it is supposed.
The liquefaction occurred due to the 2010 Chile Earthquake was mainly observed in natural ground,but, the widely spread soil liquefaction observed during the 2011 Japan Earthquake seems to beconcentrated in man-made fill, associated with reclaimed land without improvement.
ACKNOWLEDGMENTS
The author wants to acknowledge the cooperation provided by the Graduate Students of Univ. of Chile,
Mrs. Javiera Gonzalez, Viviana Gonzalez and Sebastian Maureira. Also thanks are due to Mr. FelipeOchoa for his useful comments. The financial support provided by CMGI is also acknowledged.
REFERENCES
Ruiz and Astroza (2012). “Curvas de intensidades del terremoto del 27-F”. In preparation
Ammon, C., Lay, T., Kanamori, H. and Cleveland, M. (2011). “A rupture model of the 2011 off the
Pacific coast of Tohoku Earthquake”. Earth Planets Space, 63, 693–696, 2011.
Kawabe, S., Tsukamoto, Y., Kokusho, T. and Takahashi, R. (2012). “Soil liquefaction observed at
Katori city …..”. Int. Symp. Eng. Lessons Learned from 2011 Great East Japan Earthquake. Japan.
Bray, J.D., Frost. J.D., and Rathje, E.M., (2011), “Turning Disaster Into Knowledge”, ASCE G-I
Geo-Strata, September, pp. 18-26.
K-Net (2012). http://www.k-net.bosai.go.jp/
Ramirez, N. (2010). “Effects of the 2010 earthquake on tailings disposals”. Seminar: Proposals for theoperation of tailings disposals according to recent experiences (in Spanish).
Renadic (2012). http://www.renadic.cl/red_archivos/RENAMAULE2010R2.pdf.
Tsukamoto, Y., Kawabe, S., Kokusho, T. and Araki, K. (2012). “Soil liquefaction observed at areas
located along the …...” Int. Symp. Eng. L. L. from 2011 Great East Japan Earthquake. Japan.
USGS, (2012). http://earthquake.usgs.gov/

718