M7 Canterbury New Zealand Earthquake Reconnaissance- Day 1
Travel to Christchurch -
Due to a gracious, anonymous donation and support from Cal Poly Humboldt, 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, Humboldt, 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.
Due to a gracious, anonymous donation and support from Cal Poly Humboldt, 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, Humboldt, 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.