NZSEE/AEES "Learning from Earthquakes" Mission to Chile blog by Gary Gibson
Click on image thumbnails to open a larger image in a new window. All images are low resolution for ease of emailing. High resolution versions will be available in the near future

Santiago, Chile, Friday, 2010 May 14 CST
This morning I visited Luis Merino, a mining engineer, with discussions including the effect of the earthquake on mines. This afternoon I re-visited José Cembrano from the Structural and Geotechnical Engineering Department at the Pontifica Catholic University of Santiago, to discuss geological issues that had arisen. Other members of the mission had similar activities, either individually or in pairs.
This was the last day of activities for the mission, apart from a concluding meeting tomorrow to summarise and plan a final report covering the lessons we have learned. There are no new photographs because of rain during much of the day, something that is very welcome at the end of the dry season in a very dry region.
I will complete this blog with a very brief summary of overall impressions, probably after returning to Melbourne.
We leave Santiago tomorrow, Saturday, for the overnight flight home, lose a day somewhere over the Pacific, and arrive home early Monday morning.

Santiago, Chile, Thursday, 2010 May 13 CST
Meetings today involved precast structures, reinsurance and searching archives which trace the development of Concepcion.
For the morning I returned to the Department of Geophysics at the University of Chile, to continue discussions with the Director, Sergio Barrientos, which were disrupted by TV interviews yesterday. Sergio is maintaining a very high profile, including a ten minute interview on CNN Chile TV that we watched over breakfast. There have been many questions over the tsunami warning, and many people still do not appreciate how difficulty it is to predict tsunami levels, especially on an irregular coastline. Most people living along the coast understand that long-duration earthquake shaking is nature's tsunami warning and evacuated safely, but a large proportion of casualties were due to the tsunami rather than the earthquake.
The National Seismographic Centre operated by the University of Chile, has had plans for an integrated modern ground motion network for more than a year, very similar to GeoNet in New Zealand, including broadband and short-period seismographs, strong motion, and continuous GPS to detect slow earthquakes. There are few places in the world with a greater need for such monitoring than Chile.
In the afternoon I went to the Servicio Nacional de Geología y Minería, to obtain maps and other resources. Geological maps are quite expensive in Chile and it was impractical to obtain 1: 250,000 scale maps, but I did get an impressive 1:1 million scale geological map of the country. It is printed on three sheets, each of which is very tall and narrow. Chile extends from latitude 17.5 degrees south to 56 degrees south, over 4000 kilometres. Despite limited common language, the staff were most helpful.
Santiago is operating normally, but there are signs of damage in a small percentage of buildings, and some footpaths have been roped-off due to the possibility of falling debris. The local television news services are still dominated by the earthquake and recovery news.
Art work at Santiago Airport, post-earthquake Damaged church, SantiagoSteeple repairs, Santiago

Santiago, Chile, Wednesday, 2010 May 13 CST
During the early morning, most of the group travelled to Santiago International Airport to learn about the damage and its impact on aviation from DGAC, the Civil Aviation Authority.
In the terminal building there was considerable damage including failed suspended ceilings, much of which would have at least produced injuries if the earthquake had not occurred at 03:34 am on Saturday 27 February 2010, a time when only one flight was being preparing for departure. There was considerable superficial damage in the immigration area. There were no injuries at the airport, but one pilot was killed while driving home due to a bridge collapse.
A water tank with a non-flexible connection that was used for producing fire-fighting foam failed, but four nearby fuel tanks with flexible connections did not fail, although two were damaged. The very high control tower was damaged by torsional motion, closed, and is still under repair. An older secondary control tower was re-activated and is still being used. The ground control system for aircraft at the terminal failed. Ground motion recorded nearby exceeded airport design values, and showed comparable horizontal and vertical motion.
One aircraft flying from New Zealand was diverted to Easter Island. The runway was checked immediately after the earthquake, and was declared usable 25 minutes after the earthquake. The first arriving aircraft landed at 04:25 am, 51 minutes after the earthquake. A air force base is located on the airport, and emergency flights operated soon after. On Sunday a meeting was held, and the clean-up started. On Monday the airport began receiving passengers, initially in the open-air on the tarmac, while large tents were being erected. Immigration formalities were conducted at other airports in Chile, and the aircraft then continued to Santiago as a domestic flight. Although the airport suffered considerable damage, aircraft movements returned to normal within a few days.
The airport was testing small cellphone-like radio communications, which proved invaluable when the cellphone system failed under overload. The recovery showed the value of the dedicated airport staff, the value of preparation, and the existence of an emergency plan.
The next activity was a late morning/early afternoon visit to the Ministry of Public Works, to learn about the impact of the earthquake on roads, bridges and overpasses. Three presentations were shown, covering roads, bridges and overpasses, and maintenance issues. Out of several hundred bridges and overpasses in the region, 16 were damaged and one was destroyed. Most highways are dual carriageways, so bridges and overpasses came in pairs, one old and the other newer. In some cases the older bridge failed and in others the newer. There were no cases where both bridges at a location failed, so traffic was slowed but not stopped. Bridges aligned at a skew angle performed much worse than those aligned perpendicular.
During the afternoon I separated from the group to visit Sergio Barrientos, the Director of the National Seismological Centre, operated by the Department of Geophysics in the University of Chile. This meeting was interrupted by the need for TV interviews, and we will continue discussions tomorrow morning.
No photographs today because of the nature of the activities, but copies of excellent presentations from both DGAC and the Ministry for Public Works were provided to us.

Santiago, Chile, Tuesday, 2010 May 11 CST
Having gained knowledge of the earthquake and its effects from the field studies, the mission is now in the phase where future planning issues are dominating activities. This involves meetings, generally between individuals or small numbers of people. The results will be merged in the final report.
In the morning most of our group visited the Military Hospital of Santiago (Hospital Militar de Santiago, see http://www.hosmil.cl/ for external views). Although operated by the military, most of the patients are civilian. It is one most expensive public buildings constructed in Chile over recent years, and is the largest hospital in Chile.
This modern, spacious hospital has three sections, including a well-equipped Technical section, Medical Training Facilities, and a seven-level Hospital Ward building. The technical section with its sensitive equipment, is base isolated and separated from the hospital ward building (that is not base-isolated) by a 600 mm gap and joints.
During the 27 February earthquake, a relative displacement of 220 mm was measured between the isolated and non-isolated buildings. Although there was some damage, especially at one end of the ward building, this was minor and superficial. All concerned were happy with the performance of the building in a very large earthquake. Photographs show a base isolator, one of 160 installed base isolators with plenty of fire protection, and flexibility for hot and cold water supplies.
In the afternoon we visited the Ministry of Housing, and were briefed on Chilean building legislation, regulation, and government support (grants, loans, etc). The presentation clearly outlined the relatively complex system, and clarified the place of emergency housing.
At least six other meetings were attended by other group members during the day, covering electricity supply, urban planning, architecture, environment, insurance and emergency shelter issues.
Base isolatorinstalled with fire protection Hot and cold water, allowance for movement

Santiago, Chile, Monday, 2010 May 10 CST
Our day started at 6:00 am for the flight back to Santiago. We checked into a small conveniently located hotel in central Santiago, an easy walk to the subway.
This week will be dominated by meetings and discussions, many of which will be on a one-to-one basis rather than group activities. The first half of this afternoon was spent in trying to schedule activities into remaining time slots. This was followed by the first meeting, with Chilean Structural Engineers to discuss codes, changes to codes, interpretation and compliance.
The evening activity was a New Zealand Embassy Reception, including some of the key people we have met over the past ten days. I was able to continue discussions with Engineering Seismologist, Ruben Boroschek, who is working on a strong ground motion model for Chile including the data from the February 27 event. The reception ended at 10:30 pm.

Concepcion, Chile, Sunday, 2010 May 9 CST
Only small scale field activities were undertaken today, and most of the time was spent in planning next week, sorting photographs, discussions, and walking around Concepcion. The resilience and good humour of the Chilean people, despite the problems, is evident everywhere we go. A series of commissions are being held, to identify what worked well (e.g. the electricity supply), and what should be improved (e.g. tsunami warning advice). It seems that most coastal residents are aware of nature's tsunami warning (the earthquake), and evacuated.
Few people noticed the magnitude 5.0 aftershock at 6:45 am CST this morning, about 80 km to the south of Concepcion. The Seismology Service of Chile is operated by the Department of Geophysics at the University of Chile in Santiago, and is locating an average of 4 to 5 aftershocks per day, most over magnitude 4.0.
Tomorrow has an early start for the flight back to Santiago.

Concepcion, Chile, Saturday, 2010 May 8 CST
There were three tasks for the day, the first two relating to tsunami damage.
The fishing town of Dichato is about 40 kilometres NNE of Concepcion, with a population of 3,500. The town experienced extensive destruction and about 70 people died or are missing. Most of the population knew of the possibility of tsunami after the earthquake, and escaped to higher ground. A significant proportion are now homeless, and have been living in tents. Much of the debris has already been moved, including a considerable amount temporarily on the football ground in the town centre.
Emergency housing built by the Fundacion Techo Para Christo in Coronel is being erected by the Chile army, and those people who had moved in before the heavy rains earlier in the week were very happy with the shelter provided. There is no question that the housing is temporary, but it is estimated that it will take two years to rebuild Dichato. Local residents are showing magnificent resilience, schools were opened in various available buildings soon after the earthquake, and a temporary portable school with 14 school rooms for 300 students (aged to 14 years) was completed within two months of the tsunami.
During the afternoon we visited the port of Talcahuano, about 15 km NNW of Concepcion. This was also severely damaged and several large boats and small ships were overturned or swept ashore, along with shipping containers. There was considerable tsunami damage to buildings and roads along the shore. Again, much of the debris has been removed.
In the evening until quite late, I again met with a geophysicist and a geologist/seismologist from the University of Concepcion to discuss the past, present and future.
Tomorrow is largely a rest day, with some planning for activities during the next week in and around Santiago.
Assembly of houses by the armyTemporary housing near Dichato Inland tsunami damage, Dichato
Shoreline tsunami damage at Dichato Fishing boat, Dichato Hulk in Talcahuano harbour overturned
Wharf at Talcahuano

Concepcion, Chile, Friday, 2010 May 7, 23:05 CST
Recovery day, sleeping in until 8:00 am, then spending the morning catching up on emails, organising visits for the next few days, organising photographs and writing reports.
During the afternoon, group members presented a seminar in the Faculty of Engineering, Universidad Catolica de la Santisima Concepcion, to an audience of about 80 engineers and engineering students. A series of talks and discussions on engineering aspects of the earthquake, with emphasis on the similarities and differences between Chile and New Zealand. From the point of view of a seismologist, the similarities were emphasised by a comparison of the tectonic setting of Concepcion and Napier. From an engineering perspective, many other similarities and differences were discussed, and the seminar ended after 6:00 pm following an hour long question, answer and discussion session.
Tomorrow will include field trips including one to a significant tsunami site, and to a temporary housing location. Other activities will include one-to-one meetings with local individuals.

Concepcion, Chile, Thursday, 2010 May 6, 23:55 pm CST
A number of parallel specialised activities were undertaken today, including some most informative and mutually helpful discussions involving the electricity system that will be summarised in the final mission report. I was involved in three of the activities.
In the morning we visited the local office of the Geological Survey, and were shown detailed and sophisticated microzonation studies of the city region that had been completed just before the earthquake. These included soil studies, microgravity, H/V (Nakamura) surveys and others. These showed clear correlation with the regions that showed most damage.
In the afternoon we drove to the nearby city of Coronel to visit a timber mill operated by the church-owned and operated Fundacion Techo Para Christo (www.tpcristo.cl/tpc). This was set up originally to build small low-cost houses for homeless people (typically 3 x 6 metre), with production of about one per day. Following the earthquake, the houses are being sold to the government for emergency housing, and production has increased dramatically, currently to 25 per day. The plant is working two shifts per day, and three shifts for the timber treatment operation. The houses are being transported and erected by the military. There are still over 20,000 people to be housed about Concepcion. All accommodation is limited, rents initially increased to very high levels although they are now are starting to reduce, and all hotel rooms need to be shared. Many people still live in tents, which were most unsatisfactory during the recent heavy rain.
In the evening we visited the Department of Geophysics in the University of Concepcion, to discuss their observations and plans.
After returning to the hotel a 8:00 pm, the full group met over dinner, then spent an hour or so preparing for a seminar to be given tomorrow afternoon. This will include simultaneous translation facilities in Spanish and English.
On the subject of language most of the group speak no Spanish, but one of leaders does (Hugh Cowan), together with two Chilean postgraduate students currently studying in New Zealand (Claudio Oyarzo Vera and Patricio Quintana Gallo) and their local friends. This has made a huge contribution to the planning and operation of the mission.
Tomorrow morning most people will be preparing for the seminar, or catching up on paperwork and/or sleep, and the seminar will be held during the afternoon.
Damage in Conception Fundacion Techo Para Christo
Construction of frames Raw materials Temporary Houses

Concepcion, Chile, Wednesday 2010 May 5, 11:00 pm CST
The first heavy rains since the earthquake occurred overnight and this morning, and disrupted our plans for field work today, so activities were re-scheduled. The rain caused considerable hardship for people still living in temporary accommodation, especially tents, and showed significant deficiencies in the drainage system. Fortunately the rain stopped late-morning.
While yesterday emphasised severe damage and collapse, the study today involved examination of buildings that behaved as expected or better, under the strong motion from what has been described variously as the fifth or seventh largest earthquake ever to have been recorded by seismic instruments. We have learned that the strongest ground motion recorded during the earthquake was 0.6 g, recorded at Concepcion. Although we do not yet have it, we understand that the digital record is available.
The Imagina in Concepcion is a well-built 21 storey apartment building. It was chosen as being indicative of equivalent buildings in New Zealand, and I am advised has elements relevant to Australian structures. It was severely shaken in the earthquake and has considerable superficial damage, but no known major structural damage. Like many other similar buildings in Concepcion, it is currently unoccupied, awaiting repairs.
The morning and early afternoon was spent logging the observable damage, and building plans are being obtained to gain further insight into the damage. It was explained to people in the building that earthquake design of a structure does not mean that there will be no damage in a very strong earthquake, but that much of the damage plays a part in preventing collapse of the building. Because of the heavy rain and broken windows, damage not previously obvious in this and other buildings was very evident, as in the photograph of ceiling cracks.
During late afternoon we met with the Biobio provincial staff of CONAMA, the Chilean equivalent of the EPA. A range of topics were discussed, including removal and deposition of debris, town planning issues, and location of temporary accommodation.
The plan for tomorrow is as described for today in yesterday's report.
Imagina, ConcepcionConcepcion from the Imagina buildingImagina, logging damage
Localised damageImagina ceiling cracks leaking after rain

 

Concepcion, Chile, Tuesday May 4, 11:55 pm CST
The day started at 6 am with a departure from the hotel at 6:00 am for a short flight from Santiago, south to the city of Concepcion.
Concepcion is a city of about 220, 000 people. Although life is started to return to normal, and most buildings are usable, many show no signs of damage and there are many examples of earthquake damage. Tens of buildings will require major and expensive repairs, and for at least about 8, repairs will probably not be economic. Many bridges and other structures have been damaged, and evidence of liquefaction and ground failure is common.
There are two cases of serious major damage or collapse, including the Torre O'Higgins, a new multi-storey tower which has recently been completed, but not yet occupied. One floor at about the 12th floor level has collapsed, resulting in severe damage to the whole building, which now stands in a highly unstable condition. Access is now closed in the surrounding area to everyone, and the tower stands isolated.
The Alto Rio building in Concepcion was an apartment block of about 12 stories. It was displaced and rotated 90 degrees and now lies flat on the ground. About 7 or 8 occupants were killed when the building fell, but about 80 occupants survived the fall. In the attached photograph the group member taking a photograph is facing the ceiling of the entry area into the building, now rotated to vertical.
In the late afternoon a visit was made to the nearby port facilities at Coronal Wharf. Damage and repair work were examined, and the port staff gave an informative presentation on the development of the port, the damage by the earthquake, and future plans.
The NZSEE web site will soon have more technical details. Much work is being done comparing structures and conditions in Chile and New Zealand.
Tomorrow will include site visits to bridges, embankments, reservoirs, parks and other structures, and detailed examination of sites showing liquefaction failure and ground movement.
Torre O'Higgins, Conception Alto Rio, Conception

 

Santiago, Chile, Monday 2010 May 3, 11:00 pm CST
The group left the hotel at 7:15 am this morning, with three main tasks.
The first was a visit to the Titanium La Portada Tower, the tallest building in Chile, to talk with the engineer responsible for its construction, Alfonso Larrain Vial. This was followed by a tour of the building. The tower has 7 underground levels, 52 levels above ground and a height of 188 metres. It was built from 2006 to 2010, and was inaugurated by the President of Chile this afternoon. The tower has several earthquake resistant design features, and received negligible damage in the recent earthquake.
The second task was a visit to the Pontifica Catholic University of Santiago, for presentations and discussions by Jose Cembrano on geological aspects of the 27 February earthquake, and by Christian Ledezma on geotechnical aspects of the earthquake.
The third task was to visit the University of Chile, to discuss engineering seismology aspects of the earthquake with Ruben Boroschek. This was the first great subduction earthquake to be recorded by strong motion recorders near to the fault rupture, and the data recorded will significantly improve ground motion models for all large subduction earthquakes. At present 35 strong motion records have been identified, ranging from older SMA-1 analogue records to modern digital records. They will need processing, calibration and verification before they can be used for ground motion models. Some are already available and others are privately owned.
While travelling to and between these locations, the group examined relatively minor damage to other buildings in Santiago.
At 7:09 PM CST this evening (23:09 UTC), an aftershock of magnitude Mw 6.4 earthquake occurred about 150 km SSW of the city of Concepcion. The group did not feel the earthquake, firstly because it was at the south end of the main earthquake rupture, about 580 km south of Santiago, and secondly because at the time they were travelling back to the hotel in an extremely crowded Metro train.
Tomorrow will see a 5:00 am start with a flight to Concepcion, followed by local orientation and visits to the key earthquake damage features in Concepcion. This will be followed by several days dividing into three smaller groups to study particular types of structure, the surrounding region, and other earthquake effects such as site response, liquefaction, and tsunami.
Titanium La Pagoda Tower, Santiago Santiago from the Titanium Tower

 

Santiago, Chile, Monday May 3, 6:00 am CST
The group spent a long day looking at earthquake effects in Vina del Mare, a small coastal city just north of Valparaiso. It is a relatively affluent city, and a tourist attraction where people visit to be seen. The coast line has many high-rise apartment buildings to 25-30 stories and more, reminiscent of the Gold Coast, but located on steeper topography.
No collapsed structures were seen, and most buildings appeared undamaged. However in some small regions, a relatively high proportion of buildings (including high-rise to 17 and more stories) were severely damaged, but did not collapse. It is likely that damage in at least some of these is so severe that repairs will be uneconomic. People were observed recovering their furniture from one high-rise apartment building using ropes from a window, because all other access was severely damaged. Most damage occurred in central Vina del Mar, on flat lying alluvial sediments, and it is likely that site response was a key factor. Damaged buildings ranged widely in height, design, and construction methods.
A surprising feature was the apparent lack of damage to the high-rise buildings along the coast. In driving by, no obvious serious damage was observed in any of the buildings, and life appeared to be continuing as normal. This is despite the coastline being high, dry sand dunes. It seems that some re-writing of my lecture notes regarding sand foundations will be required. It depends much on whether they are saturated or not. A new building under construction along the coast was examined, and standards seem very high, with much concrete and much reinforcement.
As with each day of the study, the evening involved a group discussion on observations, ending at 11:30 pm. At 02:49 CST (0649 UTC), as I completed sorting my report and photographs (149 for the day) there was another smaller earthquake felt gently for about 25 seconds. It was a magnitude Mb 4.8 at the same place as the larger earthquake yesterday morning. Again I was on the 5th floor of another hotel, and again it was just gentle rocking with no sound from either the earthquake or the building responding.
Today we examine damage in Santiago, and visit two universities for briefing on geotechnical and seismological issues. The assistance being provided by the local people from Chile is magnificent!

Photos of the Edificio Festival, in Viño del Mar below.

 

3 May 2010 1:56:04 AM AEST
We are in Valparaiso today, and about to head off on the first damage survey. Very little damage here, but there was considerable damage at Santiago airport. All is going well.
We just felt our first earthquake. It was a magnitude 5.8 about 120 km south of us, at 2010-05-02 1452, and was felt for about 50 seconds. Gentle rocking, no sound, and the people outside saw trees swaying. I was on the fifth floor of the hotel, and heard no associated sounds whatever. The aftershock sequence is decaying so we are unlikely to experience another of this size.