Since 1978, in-depth discussions have been held by the International Coordination Group for the Pacific Tsunami Warning and Mitigation System (ICG/ITSU, now renamed ICG/PTWS) on the establishment of regional tsunami warning centres to issue tsunami advisories tailored to individual Pacific regions. At the 14th session of the ICG/ITSU held in Tokyo, Japan, from 30 August to 3 September 1993 (IOC/ITSU-XIV), the Republic of Korea proposed that JMA operates such a centre for the Northwest Pacific region.

The ICG/ITSU, at its 17th session (IOC/ITSU-XVII/3) held from 4 to 7 October 1999 in Seoul, Republic of Korea, approved JMA's proposal to establish a regional tsunami warning centre for the Northwest Pacific. At the 19th session of the ICG/ITSU (IOC/ITSU-XIX/3) held from 29 September to 2 October 2003 in Wellington, New Zealand, JMA reported on its readiness for the centre’s operation. In 2004, the Executive Council (EC) of the Intergovernmental Oceanographic Commission (IOC) at its 37th session held from 23 to 29 June 2004 in Paris (IOC/EC-XXXVII/3) adopted resolution EC-XXXVII.4 to start the services of the regional centre at JMA by March 2005.

Based on such international consensus, JMA initiated the operation of the regional centre within the Tsunami Forecast Center at its headquarters in March 2005 to provide tsunami advisory services to the Northwest Pacific. At the 20th session of the ICG/ITSU (IOC/ITSU-XX/3) held in Vina del Mar, Chile, from 3 to 7 October 2005, JMA reported on the inauguration of NWPTAC. At the same session, the Group asked JMA to also provide interim tsunami advisory services for the South China Sea region. JMA upgraded its system and began the service in April 2006, following the endorsement of the Executive Council at its 39th session (IOC/EC-XXXIX/3) held from 21 to 28 June 2006 in Paris.

The ICG/PTWS at its 22nd session (ICG/PTWS-XXII/3s) held in Guayaquil, Ecuador, from 17 to 21 September 2007, began the process of improving PTWS international alert products starting with PTWC products. At its 24th session (ICG/PTWS-XXIV/3) held in Beijing, China, from 24 to 27 May 2011, the ICG/PTWS accepted a PTWC proposal for Enhanced Tsunami Products. After approval of the final products and the proposed target changeover date at the 25th session (ICG/PTWS-XXV), that took place from 9 to11 September 2013 in Vladivostok, Russian Federation, PTWC began issuing its new enhanced products in October 2014.

In pursuit of improvement for PTWS tsunami warning products Japan announced, at the 47th session of the Executive Council (IOC/EC-XLVII/3) held from 1 to 4 July 2014 in Paris, that NWPTAC would also be developing new products based on the requirements of user countries. The PTWS Steering Committee (SC) met later in the same month and agreed on a timeline targeting full transition to NWPTAC Enhanced Products. It also recommended that JMA continue the process of developing NWPTAC Enhanced Products for PTWS.

At the 26th session (ICG/PTWS-XXVI/3) held from 22 to 24 April 2015 in Honolulu, United States of America, the ICG/PTWS agreed that NWPTAC should proceed with its development of enhanced products for the Northwest Pacific region. Accordingly, Exercise Pacific Wave 2016 (PacWave16, IOC/2015/TS/126 VOL.1, VOL.2) and Exercise Pacific Wave 2017 (PacWave17, IOC/2016/TS/131 VOL.1, VOL.2) were conducted in 2016 and 2017, respectively, to evaluate NWPTAC Enhanced Products.

The ICG/PTWS agreed at the 27th session (ICG/PTWS-XXVII) held from 28 to 31 March 2017 in Tahiti, French Polinesia, that NWPTAC should start the issuance of its experimental NWPTAC Enhanced Products in parallel with its existing products in the second half of 2017.

To support the transition to the new products, PTWS organized two international exercises in 2016 and 2017.

PacWave16 (1-5 February 2016) served to introduce the proposed products and allow for feedback on their format and content. This feedback was considered in the development of the final products.

PacWave17 (15-17 February 2017) to allow evaluation of Member States’ interpretation of the new products accurately and in a timely manner.

The SC Task Team on PacWave Exercises oversaw the planning, execution and post-exercise evaluation of the new products and worked with PTWS WG2 Task Team on enhancing products for successful implementation.

At the 27th session of the ICG/PTWS held from 28 to 31 March 2017 in Tahiti, French Polinesia, Member States endorsed the Northwest Pacific Tsunami Advisory Center’s plan to begin issuing in experimental mode its new NWPTAC Enhanced products in 2017. After the confirmation of the starting date by SC, JMA started issuing experimental NWPTAC Enhanced Products on 20 December 2017.

The ICG/PTWS also decided at this session a targeted change-over date around one half to one year from the experimental NWPTAC Enhanced Products provision for the official full switchover to the new products. After the one year experimental term including Exercise Pacific Wave 2018 (IOC/2018/TS/139 VOL.1 REV.2), JMA has started NWPTAC Enhanced Products since 28 February 2019.

At the 28th session of the ICG/PTWS held from 2 to 5 April 2019 in Montelimar, Nicaragua, the ICG/PTWS expressed appreciation to NWPTAC for its reliable interim tsunami services for the South China Sea region. JMA stopped the interim service for the South China Sea region in November 2019 when the full operation of SCSTAC started.

NWPTAC Enhanced Products are provided alongside PTWC tsunami products to support user countries in taking timely and appropriate action against tsunami threats. However, it is important to note that the products are simply advisories to support user countries’ efforts in alerting people to hazards; the actual issuance of evacuation notices is the responsibility of the countries themselves. The accuracy of tsunami amplitude/arrival estimation times in the products and the timing of forecast issuance depend on the availability of seismic data and the technology used for hypocentre/CMT determination and quantitative tsunami forecasting. Accordingly, user countries are strongly advised to optimize their use of NWPTAC products with careful consideration of the technological background as described in this Users’ Guide.

NWPTAC makes every effort to provide its products as quickly as possible. However, people may need to be alerted in advance of NWPTA issuance in the event of large earthquakes in coastal areas, as tsunamis may reach land quickly.

NWPTAC products do not refer to the lifting of warnings in subsequent issues because NWPTAC itself does not issue warnings. These should be officially issued and lifted by the authorities of the countries concerned, as tsunami characteristics depend on coastal terrain.

In the event of any difference in tsunami severity evaluation between PTWC and NWPTAC products, the severer one should be adopted.

JMA’s NWPTA operation system is duplicated in case of partial malfunction. However, the possibility of catastrophic failure cannot be eliminated. If NWPTA products are not issued in an emergency, NWPTA user countries/organizations should take appropriate action with reference to PTWC products.