M7 Canterbury New Zealand Earthquake Reconnaissance- Day 3
Posted on September 28 2010
Telegraph Road Surface Rupture, Jumping Rocks in Christchurch, Structural and Geotechnical Engineering Meeting at Canterbury University
Rob Langridge flew back to Wellington this morning leaving the Americans to roam freely about the Canterbury Plains. Paul and I headed west this morning to look at some of the larger horizontal displacements at Telegraph Road. The road has been offset about 3 to 4 m in a right-lateral sense. A paddock (field) to the east of this large offset displays complex surface rupture. A house at the far end of the paddock was directly in line with the rupture. The house was completely shattered by the 3 m of rupture that went through it. The house has been sheared with the concrete slab foundation rotating and breaking into small, discrete blocks. We met with the homeowner who stated that it was just a bit of bad luck that he built his house directly over an unmapped fault. He stated that his paddock was nearly flat prior to the earthquake and had no idea there was a fault. New Zealand has national earthquake insurance coverage that is under the guidance of the Earthquake Commission (EQC). Their website and FAQS about the coverage can be found at http://www.eqc.govt.nz The homeowner said that his house is covered and now he has to go through the bureaucratic process to get paid.
We headed back to Christchurch to meet with Dr. Kevin Furlong (Penn State University) and a Canterbury University Ph.D. student, Nargas (I will get her last name tomorrow, apologies). We went to the rim of the large, extinct Miocene volcano that flanks the southern end of Christchurch. Trekkers found large rocks (up to 1.5 m diameter) along the crest that appear to have been thrown in the air during the earthquake. Nargas will likely map these rocks and analyze the potential high seismic accelerations that produced these jumping rocks. These rocks were truly amazing. It is hard to imagine what it might have been like to be on the ridge as rocks were literally bouncing in the air. As the earthquake occurred at about 4:30 in the morning it is unlikely there were any human witnesses.
We then went to Canterbury University with Kevin where he showed us some of the data that have been collected from the event. It promises to be an earthquake that will prove invaluable for seismic hazard studies.
We then attended a joint special meeting of the New Zealand Geotechnical Society and New Zealand Society of Earthquake Engineering regarding the engineering aspects of the Canterbury earthquake. GNS Science and Canterbury University scientists and engineers described the strong motion aspects of the earthquake, the hazard issues posed by the event and the engineering aspects associated with strong motion. I was especially impressed by the amount of liquefaction that has occurred in the area. As it turns out Christchurch is built on marsh deposits and river deposits which are notorious for liquefying under cyclic shaking. One thing that became evident from the discussions at the meeting was that many houses are built on unreinforced concrete slabs that float when subjected to liquefaction or break up when vertical deformation occurs. There is great interest in what adjustments the New Zealand government might make to the building codes to address this issue.
Paul and I are pretty exhausted but are so energized by the amazing geology and incredible work being done around here that we will likely be up again at 5 am to get going. Tomorrow is another busy day. We will be meeting with Mark Stirling, GNS Science to look at rupture and evidence for large accelerations at the western end of the event. We will work our way back along the rupture toward Christchurch. We also hope to look at some of the impressive liquefaction evidence that occurred on the outskirts of the city.
M7 Canterbury New Zealand Earthquake Reconnaissance- Day 2
Posted on September 28 2010
Surface rupture mapping in Burnham Camp meet with HSU ALumni!
We are staying in the suburbs of Christchurch in an area called Riccortan. At this location we are about 20 km from the area of maximum horizontal displacement, Burnham Camp. That is where we spent yesterday and today. We decided that it would be interesting to get an even higher resolution scan of a small section of the surface rupture to capture all of the detail, the small faults, uplifts, and fractures that comprise the very complex rupture pattern. Garth and Rob, GNS Science, set up the LIDAR to scan an area of about 50 × 50 m in dimension. The scanner rotates 360° and fires a laser (it looks like a really fancy table-top digital scanner) that collects about 15 million data points at each station. For this experiment it was moved about 6 times so they have collected about 90 million data points of the ground surface! To supplement this information, Paul used the Real-Time Kinematic GPS to make small features, mainly fractures, that have no vertical relief on them that the scanner might not see. Additionally, Rob created a sketch map (old-fashioned geology) of the scanner study just to see how accurate the old method is compared to the high-tech method.
It should be noted that this part of South Island, along the eastern coast, is referred to as the Canterbury Plain, a flat and vast sheet of post-glacial outwash gravels that is 40 to 50 km wide and extends for more than 200 km along the east coast of the island. Great rivers, such as the Rakaia and Waimakariri, carry enormous amounts of sediment from the Southern Alps and their eastern ranges toward the ocean to produce this plain. It is thought that the age of the surface (except for the active river areas) is on the order of 14,000 to 16,000 years old. That age corresponds with the best estimate for the last glacial maximum for South Island. For the most part, the Canterbury Plain has little relief on it. Thus, unlike many western US fault ruptures that break across hills, mountains, valleys, etc., this fault has broken across a nearly flat datum. It stands out very clearly.
I got to hike WSW along the rupture to explore more of the details of this fault. As the fault makes small turns and jogs, the nature of the surface rupture changes. In some locations it suddenly dies out and then steps a few hundred meters, where it continues on. A large high-tension electrical transmission line traverses the rupture. One of the towers was moved more than 3 m with respect to the two towers on either side of it. The only evidence for this motion was the tension of the power lines. To the north, the towers moved closer together and the lines sagged. To the south, the towers moved apart and the lines are now quite tight and straight. Remarkably, the towers withstood the strong ground shaking and surface displacement with failing and the high-tension lines are still producing energy. I’m sure, at some point, the electrical company will make some adjustments to the lines.
Prior to coming to New Zealand I got an email from Rebecca Teasley, who said that her mother sent a copy of the HSU press release announcing that Paul and I were headed to Christchurch. She said that she and her husband, John Allen, were Humboldt natives and HSU graduates now living in Christchurch. In fact, John was in my first geomorphology class. They are both graduates of the HSU Environmental Resources Engineering program at HSU. Becky is finishing a post-doctoral program at Canterbury University. We met this evening in old, downtown Canterbury for dinner and beers. What an amazing thing to walk in and see John after all these years! John is a geotechnical engineer and has been working closely with the Geo-Engineering Earthquake Reconnaissance (GEER) team that flew in shortly after the event to document the earthquake damage. John and Becky got out into the field almost immediately after the main shock and got great photos of the surface rupture. The highway department here was amazingly quick to start repairing damaged roads so John and Becky’s photos are going to prove to be a great resource. It was sure a pleasure getting together with them to talk about the event, and, of course, Humboldt!
We also met with Dr. Mark Quigly, a geology lecturer with Canterbury University, and Dr. Kevin Furlong, professor at Penn State University. Mark has been directing much of the on-the-ground activity. Kevin was here on sabbatical. I don’t envy Mark’s schedule trying to get students into the field, dealing with the onslaught of visiting scientists and teaching at the same time! The Canterbury folks are doing an incredible job!
It was a long day. Tomorrow we are spending the morning toward the western end of the rupture near Horarata. They had ground accelerations there that approached 1g. In the afternoon we are meeting with Kevin and one of Mark Quigly’s students in Christchurch to look at evidence for boulders having been thrown out of the ground. This evening we meet with Mark Stirling (GNS Science) who will be presenting a talk on the hazards mapping projects he has been conducting for New Zealand.
As we have travelled through Christchurch we have noticed that the damage is extensive. There are many brick (unreinforced masonry) buildings, many of which have damage but many that do not. John Allen was saying that those buildings that had even minimal seismic structural upgrading seemed to perform pretty well while almost all that failed had no seismic retrofitting.
M7 Canterbury New Zealand Earthquake Reconnaissance- Day 1
Posted on September 27 2010
Travel to Christchurch –
Due to a gracious, anonymous donation and support from Humboldt State University, I have been given the opportunity to bring my graduate student, Paul Sundberg, to document the aftermath of the M 7.1 September 4, 2010 earthquake in South Island. Paul is making a decision about the direction of his MS thesis, which will be fault-related, so this seemed like a wonderful opportunity for him to see the geomorphic expression of a surface rupture.
I’d like to thank Dr. Lori Dengler, HSU, for her help with many logistical things that have made this trip possible. In addition, we are also here as part of an Earthquake Engineering Research Institute (EERI) post-earthquake reconnaissance effort. Most of the people involved with that initial team have already left the country. We are doing additional work, as needed, to help them.
I’m going to attempt to keep this blog updated daily. However, we are trying to cover a lot of ground and see as much as we can so there may be a skipped day occasionally. Additionally, as I am either writing this very early in the morning or late at night, please consider it a draft writing, at this time.
Our trip began with a long (7 hour) layover in LAX immediately followed by a 12 hour flight to Auckland. Air New Zealand is one of the best airlines. On the way we crossed the International Date Line and lost a day so we left LA Friday evening and arrived in NZ Sunday morning.
We arrived in Christchurch to beautiful Spring weather we a stout Northwesterly wind blowing. After making arrangements like getting a NZ phone and getting our car we contacted my good friend Dr. Robert Langridge who is a geologist with GNS Science, the NZ equivalent of the US Geological Survey. Rob and I went to graduate school at the University of Oregon. In 2008 my family and I lived in the Wellington area and worked for GNS Science during my sabbatical. Rob and I worked together then on faults on both North and South Island. Rob is doing some detailed mapping of the rupture and invited us to join him.
Of course, getting out to the rupture site required a few minutes of driving re-orientation since New Zealanders (Kiwis) drive on the left side of the road. The driving part took no time to remember, however, the turn signal and windshield wiper stalks are on opposite sides of the steering wheel than I’m used to so every time I’ve turned I’ve managed to wash the windshield.
The surface rupture for this event is spectacular and extremely complex. The event was almost purely right-lateral strike-slip. The only vertical sense of displacement, on the main trace of the fault, appears to be where there are small turns in the main trace of the fault. For the most part, the fault has ruptured through pasture and farm land. There have been some houses and farm buildings that have suffered directly from the surface rupture but, significant displacement (up to 4 m) has been documented across cultural features like roads, fences, windrows and drainage canals.
Paddocks, bound by fences and windrows and access roads provide excellent piercing points to document amounts and style of slip. GNS Science has put technological advances to great use to collect surface rupture data. They have flown airbased LIDAR, INSAAR and high-resolution photography. In addition, they have conducted real-time kinematic GPS (RTK) surveys of the entire 22 km rupture. They are now mapping selected portions of the fault using a high-resolution ground-based LIDAR laser scanner, combined with digital imagery and GPS location. This will likely prove to be one of the best imaged surface ruptures in the world, to date.
Our first day was spent walking about 2 km of the rupture in the vicinity of Kivers and Highland Roads near the town of Burnham. The surface trace of the rupture is unlike any I’ve seen before. It is not a simple single straight surface rupture but, instead, a series of en echelon steps and bends comprised of a zone of faults and fractures of many orientations withiin a zone that ranges in width from 10 m to > 50 m wide. Nearly everywhere we observed the rupture yesterday, the ground surface was mounded about 1 to 1.5 m high. This linear mound contained the zone of faults. Individual faults typically have only a few cm of motion but cumulatively make upwards of 4 m of lateral slip.
As it was a Sunday, many folks from around the area were out to look at the rupture. Therefore, we also spent time talking to them about the earthquake, how we go about studying the faults, both before and after an event, and, very importantly, their observations of the earthquake.
There have been an impressive set of aftershocks to go with this event, including 3 ~M4 events two nights ago and 3 felt events yesterday. This earthquake is not letting folks forget about it.
At the end of the day we shut down the LIDAR scanner just as the sun was going down.
We are returning to the site today where Paul and I are going to use the RTK system to map some of the detailed fine-grained faulting to supplement the GNS data.
Chile Earthquake - Tsunami Reconnaissance Day 11 & 12
Posted on April 06 2010
Saturday and Sunday, April 3 & 4
Troy, Nick, and I spent the morning working very hard to pull our report together. Pancho and Sebastian joined us after lunch to prepare for the exit briefing with ITIC and UNESCO staff. We identified factors that effected impacts and made a number of recommendations. In a nutshell, the factors that reduced impacts were:
• Public Awareness (drills, education programs, previous experience, signs, culture)
• Time of day, day of the week (earthquake)
• An educated public
• Engineered structures
• Availability of high ground (with a few exceptions)
• Resilient organizations like Radio Bio Bio.
• A developed country with technical, scientific, and engineering capacity.
• Availability of tsunami inundation maps for a number of areas.
Factors that exacerbated impacts
• A very large earthquake, damaged infrastructure (particularly roads and communication) and large near-source tsunami.
• Time of day, day of week, and time of year – this reduced earthquake impacts (people at home sleeping) but increased the tsunami exposure (people camping) and difficulties in evacuating (night).
• Inability of the normal response personnel (police, fire) to respond in urbanized areas like Concepción.
• Vulnerable campgrounds with no tsunami information.
• Lack of security delayed response for several days in some areas.
• Planning for tsunamis was lower priority than planning for earthquakes in urban areas.
• Variable education/outreach/signage/drills efforts. Extensive programs in some communities, few in others.
• Signage doesn’t connect the earthquake and the tsunami. Signs point out tsunami hazard zones, or tsunami evacuation routes but don’t mention that the ground shaking is the natural warning.
• Barriers to evacuation – no way to get off the island in Constitución.
• Worries about impacting tourism caused some resistance among business owners to tsunami education efforts.
• Ignorance or false expectations: Some expected to see the water drawdown first, or expected to hear a siren or receive an official notification.
• Largest surges in some areas came very late (as much as 4 hours), people re-entered hazard zone, and in some cases, had to re-evacuate one or two more times.
• Few people had personal plans – people left without shoes, and had no pre-arranged meeting places.
Based on what we saw and learned, we’ve made a preliminary list of important lessons for the United States, and the Cascadia region in particular.
1) School curriculum. No question that Chilean coastal communities have gone much farter than California is school programs teaching tsunami safety. Institutionalizing earthquake/tsunami education programs in schools would go a long way towards producing an aware population.
2) Seminars/Workshops. Classes and workshops were frequently identified as the source of preparedness information. Even if only a small percentage of the population attended, the information was spread informally.
3) Physical barriers to evacuation. All regions of the U.S. Should be carefully reviewed for cases where coastal residents or visitors cannot reach high ground soon enough to avoid tsunami inundation. See the blog description Day 8.
4) NOAA Weather Radio (NWR). The lessons learned from Radio Bio Bio have some relevance to the role that NWR can play after an event has occurred. The two screaming messages from Radio Bio Bio’s experience are that silence should be avoided at all costs, and that the silence should be filled with meaningful information. While the NWS already recognizes the importance of keeping NWR functioning, some thought needs to be given to what would be broadcast in the hours and days following an event. Without advanced planning, NWR may simply default to providing the weather forecast when there is more urgent information that could be provided. Examples of information that could be provided by NWR includes: which radio stations are providing information, where to find medications, which roads are impassable, where meeting places have been designated, information about the recent event, and where food and water is being disturbed.
5) Coastal Campgrounds. The message from the event in Chile is tragically clear: Special care must be given to the education of visitors to tsunami hazard areas in the U.S. This education must be aggressive and must use active methods whenever possible. An example of an aggressive method would be to place tsunami signs above urinals and on stall doors in bathrooms – making them difficult to ignore. An example of a active method, where applicable, would be to train park staff to provide verbal and written education information to campers when they check in. Additional recommendations will be developed in the coming weeks.
6) Connecting earthquakes and tsunamis, and the natural warning. The majority of locals we talked to knew that the strong earthquake indicated a tsunami would occur, and to therefore evacuate immediately. Evidence indicates that visitors to the coast did not make this connection. In the case where they were warned, by the police, for example, they survived. In the cases where there was no opportunity to warn visitors, there were significant fatalities. The message for the U.S. Is clear: for regions where a significant near-field tsunami threat exists, education that focuses on people responding based on a felt earthquake is of the highest importance.
7) Set nature of tsunamis. The Chilean event, as well as historic North Coast tsunamis (2006, 1964), continue to suggest that people are not understanding that tsunamis last for a long time. Our messaging is not working, and our group concludes that the problem is that we are not addressing the temporal non-homogeneous nature of tsunami wave arrival times. People are lulled into a false sense of security when an hour or two passes with no additional waves. We must address this in our educational messaging and in the wording of our warning products. Interestingly, this is aspect of tsunamis is very similar to that of sneaker waves that claim many lives on the West Coast each year. There may be an opportunity, and benefits, to cross utilization of phrases and wording.
8) Drills. In coastal communities where drills had taken place before this event, many interviewees mentioned that the drills enabled them to remain calm during the earthquake and to evacuate effectively. In contrast, some community members in Constitución evacuated so hastily that they didn’t even put shoes on. This actually slowed their evacuation because they had to walk through debris and broken glass. Giving people calmness an the resultant clarity of mind needed to make decisions in a stressful situation is a recognized benefit of drills. While drills are already a best practice for Tsunami Ready communities in the U.S., their actual use is limited. Drills should be conducted more aggressively, especially for schools and other public facilities in the tsunami hazard zone.
After the briefing it was time to pack up and leave. We were advised that the concessions in the airport had not reopened because of the earthquake damage, and the only place open to eat was possibly the worst Chinese restaurant I’ve ever eaten at. But no harm done, The food, accommodations, and company on this trip has been outstanding. In the airport I ran into Bret Luzinda who I had worked with on a reconnaissance study of the January 9 offshore Eureka earthquake. He was returning with a group of engineers from the Applied Technology Council who were looking at design, code and tagging issues. It’s a fairly small group of people who do post event assessment and I often run into people I know coming and going. We faced the usual trials on the homeward trip – delays and missed connections – that set us back a few hours. A rude shock to go from warm, dry, early fall conditions to a full blown winter storm complete with snow in Laytonville. We heard about the Baja earthquake near Healdsburg. No – the number of earthquakes is not increasing, but exposure and vulnerability is and this year we had the bad luck of a magnitude 7 (Haiti) located in nearly the worst possible place. But I’ve had enough to last me quite awhile.
Chile Earthquake - Tsunami Reconnaissance Day 10
Posted on April 06 2010
Friday, April 2
Fortunately no strong earthquakes in the night so I didn’t have to try out my evacuation strategy. First access to internet in three days – but only if I sit out in the driveway near the manager’s building where the router is located. Amazing how quickly an inbox fills up in three days. We had a late morning – breakfast served on the porch in front of our rooms. The sky is clear and the community expectant of a large crowd of visitors for the three day weekend. It’s Good Friday, a national holiday, and many people from Santiago and other inland cities head to coastal towns. The towns from Pichelemu and north were not hard hit from the tsunami and are only a couple of hours drive from Santiago. The mood here is much different than in the towns further south, no one seems much interested in the earthquake or tsunami and there is an insistence that everything is normal. There’s an interesting video posted on Youtube from this area of a young man joking about the tsunami as it comes in. You can see how modest the waves are, but still enough to pull him under the water and struggle with the surges. Afterwards, he is still hamming for the camera. You can see it Here.
We arrive back in Santiago early afternoon and spend the rest of the day pouring through our notes. We have an exit briefing scheduled with UNESCO tomorrow afternoon. It’s good to have the deadline and get a preliminary report pulled together before we leave. I’m already thinking of the stack of work in my office I’ll face on Monday and know that the time to write up a summary report. Sebastian wanted us to experience the “gran lomito tomate palta completo” sandwich, a Santiago classic consisting of a bun the size of a plate stuffed with avocado, pork, sauerkraut, and about a ¼ cup of mayonnaise. His favorite restaurant was closed because of Good Friday, but we found a reasonable substitute. I can’t think of the right words to describe them. We made it through about half and boxed the rest for dinner.