Written by Sheng-Lin Lin, Risk Engineer, GNS Science
The tsunami survey is a research initiative funded by the New Zealand RiskScape programme (www.riskscape.org.nz) in partnership with the University of Canterbury and theStIRRRD programme.
Yesterday (16/11/18) morning we continued ourdamage survey in the east side of bridge but further north, as shown in thesurvey point distribution.
In the afternoon, we visited Balaroa, one of the
liquefaction areas near Palu.
As shown in the image, the damage/impact is impressive and very sad.
We thought some damage might come from
liquefaction, but the majority of the houses were swallowed/damaged by the
landslide/mudslide as the scale is unbelievable.
I’m on the way back to Wellington, but the team will continue their field survey today (Saturday), and head back Jakarta on Sunday,have debrief meeting on Monday in Jakarta with ITST, and then head back NZ on Monday late afternoon.
Written by Sheng-Lin Lin, Risk Engineer, GNS Science
The tsunami survey is a research initiative funded by the
New Zealand RiskScape programme (www.riskscape.org.nz)
in partnership with the University of Canterbury and the StIRRRD programme.
Summary – 15/11/2018
Yesterday (15/11/2018) morning we continued our damage survey (incl. inundation depth measurement) in the west side of bridge,and we moved to the east side of bridge in the afternoon.
As shown, we have covered the majority of the
waterfront area, we will continue the east side today, and might check other
place this afternoon.
Though it’s an unfortunate event, my observation isthat people are still very positive and keep moving on (exact message from theimage took from a shop near the collapsed bridge)
PS. Felt first aftershock since arriving couple hours ago, a moderate one?!, We weren’t worried too much but it came after power outage, so made things interesting. The power is back so we are fine now, and I can share our survey activities with you…😊
Written by Sheng-Lin Lin, Risk Engineer GNS Science
The tsunami survey is a research initiative funded by the New Zealand RiskScape programme (www.riskscape.org.nz) in partnership with the University of Canterbury and the StIRRRD programme.
Summary – 13/11/2018
Day one the survey team traveled to Palu City from Jakarta on an early morning flight. Gumbert Maylda Pratama met the team at Palu airport before attending a meeting with colleagues at Tadulako University (UNTAD). The New Zealand-Indonesian team carried out a survey recognisance trip along the Tawaeli to Palu City coastline, stopping at key sites such as Kampung Nelayan to observe road infrastructure damage.
Travel from Jakarta to Palu arriving at 6:30am.
Visit Palu River Bridge to see the reconstruction activities.
Meeting with Amar Akbar Ali, Pak Ketut, Andi Rusdin and Ida Sri Oktaviana at UNTAD Engineering Department.
Travel to Port of Pantoloan with Pak Ketut and Ida Sri Oktaviana for observations of tsunami flow depths and building damage.
Travel to Palu City along coastal road, stopping at Kampung Nelayan to observe road and sea wall damage
Tsunami Hazard Observations
Tsunami flow depths above ground and inside buildings were observed and measured for buildings and surrounding features at Port of Pantoloan. Flow depths were observed onsite but not systematically recorded using a field data collection application.
Tsunami Flow Depths
Several measurements from water marks inside ferry service terminal building (Pelabuhan Palu – see image below) indicates flow depths may have reached 1.7m above ground. This height was consistent with debris deposited on wire-mesh fencing within 20m of terminal building.
Tsunami Damage Observations
Building and infrastructure damage was observed during recognisance along the coastline from Tawaeli to Palu City. The survey team made two stops at Port of Pantoloan and Kampung Nelayan based on the recommendations of UNTAD colleagues. Damage characteristics were observed but not systematically recorded using a field data collection application.
Port of Pantoloan
Flow depths inside ferry terminal buildings reached maximum of 1.7m, though lower depths of 0.33m were measure from debris marks indicating still water levels.
No structural damage observed for one and two storey concrete masonry buildings, with non-structural components more readily damaged. Non-structural damage observed on first floor level includes:
First floor window frames and glass completely damaged where flow depths exceed 1.5m.
Air conditioning service wiring and condenser units completely damage when located low to ground (i.e. <1m).
Tiles removed from first floor level, floor material and foundations undamaged.
Damage to internal doors i.e. warping and swelling.
Fixtures and fittings including joinery were removed from buildings.
Electrical items including, power socket and switches were inundated and remained in situ, although replacement or reconditioning would be required before reuse.
Minor damage (e.g. impact cavities, stripped paint) to external walls due to floating objects. No cracking observed.
Noted that the ferry service was moved to another further north port prior the Palu-Dongala earthquake tsunami, hence limited human impact during the event.
Tawaeli to Palu City
Extensive damage on low-lying coastal land, with many buildings potentially experiencing collapse or washed away (we will need to verify with other researchers).
A number of damaged building sites identified for survey activities.
Caution will need to be exercise during any survey activities as many residents who lost homes have set-up camps.
Many roads within observed inundation area have performed well (DL0-DL1). Localised damage was observed (DL2-DL3).
DL2– DL3 (Moderate – Complete) damage observed South of University of Tadulaku
Extensive seawall scour observed with loss of one or two lanes of road. Blow out observed at culvert (DL2).
Peeling of pavement observed (DL1).
Many utility poles were observed to have performed well (DS0). Bolted embedment type poles observed at Pontaloan Port (where damage was observed on other assets)with no signs of damage (DL0)
Localizedareas of damaged utility poles (DS2) observed.
Electricitypoles South of University of Tadulaku observed with lines pulled from poles(DL1 – DL2)
Earthquake Damage Observations
Though the focus of this survey is Tsunami impact to buildings and infrastructures,earthquake damage was also observed and recorded when available.
The airport is still operating (only ground floor, the upper floor was closed) though its substantial non-structural damage and wall cracks.
demolition of the damage bridge is underway as shown below (left).
multi-story building nearby was also damaged by earthquake shaking (and tsunami?!)
of buildings in the campus were affected by the earthquake shaking. Some of
them was closed due to its severe damage and safety issue, such as the Faculty
of Engineering building shown below.
and staff are back school now. But with limited facilities after the
earthquake, some students and staff are relocated to other universities
Ketut and his team had conducted detailed assessment of damage buildings in
Tadulako University as well as buildings within Palu city.
Port of Pantoloan:
damage in Port of Pantoloan is believed to be caused by earthquake shaking,
such as the collapse of crane (left) and the collapse of brick wall (right).
No-one involved in the Seismometers in Schools project wanted to see their work put into action as quickly as it was in Palu. In March 2018, three schools in the City of Palu had Raspberry Shake seismometers installed; on 28 September, a 7.5 magnitude quake in the North Sulawesi subduction zone and a subsequent tsunami killed at least 2100 people in Palu City, Donggala and Sigi. Nearly 700 are still missing and close to 80,000 people remain displaced.
A couple of days later, Richard Woods from the StIRRRD team noticed that the Raspberry Shake at the SMA Negeri Model Terpadu Madani (located in the north of the city of Palu) was back online, as power was restored to the school.
The seismometers in the three schools helped to build a picture of what happened that day. The severity of the shaking was obvious, and we can only imagine how terrifying the earthquake must have been.
The first image below shows the seismic trace up until the M7.5 struck just after 6pm. You can see the M6.1 foreshock earlier in the day and the aftershocks in between the two earthquakes. The second image shows the seismometer had power restored just after 12.15pm on 07/10, and the third image shows the UNTAD seismic trace on the 16th of October, interspersed with many aftershocks.
Richard then noticed that the Raspberry Shake located at MAN 1 school in the city of Palu, had also come back online, and like the first image above, the severity of the shaking is very clear.
For StIRRRD program leader Michele Daly and the wider team, the realities of the recent earthquake and tsunami are confronting. It’s one thing to be aware of the destructive potential of these natural hazards, but quite another to see events play out so soon. The StIRRRD team had visited Palu just six months before, and no-one could have predicted having to deal with such severe impacts so soon.
Michele described it as ‘heart-breaking’ to see so much destruction and human cost. But she was also amazed at how rapidly people have mobilised to support each other. She says that going by her experience of the wonderful people of Palu, she is sure this will continue throughout the recovery.
So, what are GNS Science and the StIRRD team doing to help?
The StIRRRD team is part of the response effort, supporting the Indonesian government and in-country partners with their response efforts. GNS Science has many experts in response and recovery following earthquake and tsunami events, and New Zealand’s Ministry of Foreign Affairs and Trade (MFAT) asked GNS and the StIRRRD team to lead a NZ inclusive approach, providing Palu with technical support in the transition from response to rehabilitation and recovery.
The immediate focus is to support MFAT and local agencies in Indonesia to carry out earthquake damaged building assessments and landslide risk assessment. The StIRRRD team are working with GNS experts and liaising with a variety of NZ and Indonesian partners, and this work is likely to continue in the longer term – with an emphasis on resilience and building back, better.