2 October 2018
On Friday Evening, a 7.5 magnitude earthquake struck near the city of Palu on the island of Sulawesi. The quake and resulting tsunami killed at least 800 people and displaced more than 50,000.
These numbers are expected to grow as the rescue teams reach areas cut off by landslides. Today, Foreign Affairs Minister Winston Peters has announced New Zealand will provide $1.6m to assist Sulawesi earthquake and tsunami response.
The SMC asked experts to comment on the disaster. Please feel free to use these comments in your reporting.
Dr Willem de Lange, University of Waikato, comments:
"We undertook an assessment of the tsunami hazard of the Makassar Strait region of Indonesia, which included the west coast of Sulawesi, in the late 1990s. This area was identified as a high-risk region with six major tsunami events between 1900 and 2000 within the Strait (one-third of Indonesian events last century).
"An aspect of concern was that some events produced localised large tsunamis that exceeded the magnitude we would expect from the size of the earthquake. This suggested that submarine landslides contributed extra energy to the generated tsunami waves, increasing their size.
"Unfortunately this complicates providing reliable warnings, as the waves can be larger and arriver sooner than predicted.
"Based on the magnitude of the earthquake, authorities warned of possible tsunami waves between 0.5 m and 3.0 m. Observations reported in the media, indicate that their predictions were reasonable for most locations, but that some areas may have experienced larger waves than predicted in the warnings."
Note: We have a hazard map from Willem published in 2001, showing Palu to be an area at high risk of tsunami greater than 3 m in height.
Joint statement from GNS Science and the Ministry of Civil Defence and Emergency Management GNS Science:
"It’s unclear what caused the devastating tsunami in this tragic event. Scientists have a reasonable understanding of the earthquake, but not the precise cause of the tsunami. While we don’t have all of the details on Indonesian warning arrangements, it’s a timely reminder of what to do in New Zealand, where we are also prone to local earthquakes that can generate large tsunamis.
"This event reinforces the importance of natural warning self-evacuation often referred to as 'Long or Strong, get Gone' for coastal regions that are close to and feel large earthquakes. Most of the time that a local earthquake generates a large tsunami, where felt shaking occurs, strong shaking is the first and most reliable warning in the closest coastal areas that a tsunami may be coming.
"Meanwhile for life safety, self-evacuation is important and every minute counts after the long or strong earthquake. People should not wait for anything, they must know their evacuation zone and routes and walk, run or cycle immediately to safety.
"New Zealand has official warning systems in place, including enhancements to the national geohazards monitoring programme, GeoNet, and the use of Emergency Mobile Alerts, to support felt shaking. These systems will be used when possible, and as soon as practicable in any tsunami event, noting the first waves may arrive before these official warnings are issued."
Note: A GNS researcher who held a workshop on disaster resilience in Palu earlier this year is preparing a blog post on the topic.