Publication Date:
2022-08-12
Description:
A series of severe earthquakes hit Central Chile on Saturday, 27th February 2010. The main shock off Concepcion at 06:34 UTC (3:34 AM local time) had a magnitude of 8.8 Mw. The Pacific Tsunami Warning Center PTWC in Hawaii, USA issued a regional warning at 06:46 UTC (12 minutes after the event). This was the first ocean wide test of a system that was put in place nearly 45 years ago by UNESCO’s Member States through its Intergovernmental Oceanographic Commission (IOC), after a 9.5 magnitude earthquake on 22 May 22 1960 off Chile triggered a wide ocean tsunami that caused 61 fatalities in Hawaii and 142 fatalities in Japan, several hours after the earthquake. As indicated above, 12 minutes after the 27th February 2010 earthquake the Pacific Ocean Tsunami Warning System (PTWS) went into action, with timely and adequate information produced and disseminated across the Pacific Ocean. There were no fatalities reported far from the epicenter, however, near the epicenter off the Chilean coast, official accounts indicate over 156 fatalities due to the tsunami. Preliminary measures of a Rapid Survey Team deployed the week after the event by UNESCO showed run up measurements as high as 30 meters with most common measurements between 6 and 10 meters in the most affected area of the Chilean coast. This earthquake and tsunami event presented an ideal opportunity to assess the performance of the PTWS. To that end the UNESCO/IOC Secretariat for the PTWS sent out a post-event survey questionnaire to the Tsunami Warning Focal Points (TWFPs) and Tsunami National Contacts (TNCs) from its 32 Member States and territories. This report has been prepared by the Secretariat based on the responses received from 19 TWFPs and TNCs. Factual details of the earthquake event and the tsunami are presented and the results of the survey are listed in tables and displayed as timelines and maps. We underscore that all TWFPs received the first PTWC bulletin. In addition, most of the countries reported PTWC as source of awareness of the earthquake. Fourteen countries issued a tsunami warning and in 9 Member States coastal zones were evacuated. It would be pertinent that each Member State analyze if an evacuation would have been necessary in zones where no evacuation was made. In four countries, some areas were evacuated preventively (self-evacuation). Moreover, it was observed that sea level was monitored by most of the countries. In addition, some countries used results from numerical modelling and calculated earthquake parameters. Based on data and information collected from Member States the PTWS acted promptly and efficiently throughout the Pacific. However, and at the same time, this event demonstrated the need to reinforce the work of PTWS for near field events, particularly with denser sea level real time networks close to active subduction areas. Indeed, as it has been demonstrated by the case of the sea level station located in Talcahuano, Chile, sea level stations close to the epicenter may be partially or totally destroyed by the impact of an earthquake and/or a tsunami. Given the critical role sea level readings have in all tsunami warning systems, the sea level monitoring networks should be densified close to active subduction areas and redundancy of sensors and transmission paths be strongly considered. Most of the issues revealed by the survey can be addressed both by the PTWS and at the national level through increased regional cooperation and training where needed. Post-event assessments assist in this process by highlighting the strengths and weaknesses of the PTWS at regional, national and local levels and by raising the awareness of how Member States responded, both individually and collectively. The true value of such assessments is that it allows Member States to share information and experiences for the mutual benefit of improving the PTWS performance for all members.
Description:
OpenASFA input
Description:
Published
Description:
Non Refereed
Keywords:
Tsunami
;
PTWS
;
Earthquakes
;
Pacific Tsunami Warning and Mitigation System (PTWS)
;
ASFA_2015::T::Tsunamis
;
ASFA_2015::E::Earthquakes
Repository Name:
AquaDocs
Type:
Report
Format:
159pp.
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