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Joint Research Centre, I-21020 Ispra (VA), Italy

EUROPEAN COMMISSION JOINT RESEARCH CENTRE

Thursday, 17 September 2015

Mw 8.3 Chile – Earthquake and Tsunami Chile, 16 Sep 2015 22.54 UTC (19.54 local time)

Last update: 17 Sep 2015 19:00 UTC

1 Executive Summary A major earthquake of magnitude 8.3 Mw at a depth of 25 km occurred on the 16th of September at 22.54 UTC in the Pacific Ocean, in the sea area west of central Chile, very close to the coast. The epicentre was located approximately midway between the port cities of Valparaiso and Coquimbo, ca. 250 km NW of Santiago. USGS-PAGER estimates 42 000 people exposed to “Severe” and more than 800 000 to “Very Strong” shaking. The earthquake triggered a significant tsunami that reached a measured max. height of around 4.8m at the Chilean coast near Coquimbo. The whole of the coast of Chile was put on Red Alert by the local authorities following the event, and a Tsunami Threat Message was issued by the Pacific Tsunami Warning Centre for a large part of the whole Pacific coasts. Coastal evacuations were promptly ordered by the Chilean Authorities and around 1 million people have been evacuated according to media reports. Aftershocks as strong as 7 Mw followed the main event.

As of early on 17 September, Chilean authorities and media report five people killed by the direct effects of the earthquake (falling debris). Worst affected by building damage and landslides are the communities of Illapel, Canela and Salamanca; Choapa province was declared a disaster zone. Media reports also show coastal flooding by tsunami; the extent of tsunami damage was not ascertained yet, as of 10:00 UTC on September 17. JRC calculations estimate a maximum tsunami height of 7.5 m occurring in the location Los Vilos.

The JRC is following the event closely. GDACS issued a first Orange Alert approx 6 min after the event, followed by a Red Alert 20 min after the event, when the conditions were revised by seismological organizations. A brief report on the event was issued by the JRC-centred GTIMS2 partner network of seismological centres 1 hour after the event, followed by a more extensive report within 3h from the event. Copernicus Emergency Mapping Service was also activated by the Emergency Response and Coordination Centre on Sep. 17.

Figure 1- Map of the earthquake's area

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Joint Research Centre, I-21020 Ispra (VA), Italy

2 Situation Overview

2.1 Event details and risk

Event Location and Significance: The 8.3 (moment magnitude) earthquake struck on 16/09/2015 at 22:54 UTC or 19.54 local time, under sea but very close to the coast (around 5km from the ocast and 45 km west of the town of Illapel. The hypocentre depth was 25km. It was widely felt all over the country and as far as Buenos Aires in Argentina. It is considered a major event, and it is the strongest earthquake in the world since April 2012 and the largest in Chile since February 2010 (the tsunami in 2010 killed more than 500 people).

Alerts: The whole of the coast of Chile was put on Red Alert by the National Authorities and a Tsunami Threat Message was issued by the Pacific Tsunami Warning Centre for a large of the whole western American coast. For the alerts issued by GDACS and the Joint Research Centre, see Section 3 of this report.

Seismic Hazard: The undersea earthquake was close enough to the shore to cause significant damage by shaking; however, no major populated places were very near the epicentre. USGS reports “Severe” shaking (VIII in the Modified Mercalli scale) for 42 000 people; this intensity can cause moderate to heavy damage, particularly in weak structures. Another 800 000 people were subjected to “Very Strong” shaking (MMI VII), including the cities of Illapel (23 000 people, closest city to the epicentre), Coquimbo (160 000 people) and La Serena (155 000 people).

Tsunami Hazard: Earthquakes of this magnitude can produce very dangerous tsunamis, and close to 1 million people were ordered to evacuate coastal areas

2.2 Impact on population and infrastructure

Despite the large magnitude, the high intensity and the tsunami, damage and casualties seem to be quite limited, at least as of midday of 17 September. Emergency authorities report 8 deaths (4 of them in Coquimbo) of which only 4 seem to be directly caused by the earthquake (falling debris). Media reports later in the afternoon quoting ONEMI officials raised the number of deaths to 10. 135 000 households are reported to be without electricity in Coquimbo Region, 1 800 households without drinking water in Illapel, 1 300 households without drinking water in Salamanca. The road network affected due to landslides in the Coquimbo Region – the province most affected is Choapa (declared a disaster zone), most adjacent to the epicentre and particularly the communities of Illapel, Canela and Salamanca. As of early afternoon on 17 September there were reports of coastal damage but no exact information on the effects of the tsunami, except some photos of damage in ports.

Figure 2: Damage by tsunami in Chile (Photos by "El Mostrador" and "La Segunda")

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Joint Research Centre, I-21020 Ispra (VA), Italy

In general, Chile exhibits a high resilience to strong earthquakes in the past few years (especially after the major event of 2010) and the population is considered rather well prepared. A number of recent strong earthquakes in the area (including a major 8.2 earthquake in 2014 that triggered a tsunami of around 2m) off the coasts of northern Chile also helped keep readiness at a high level. The Tsunami Early Warning system worked properly and alerted the population in time to avoid major consequences.

3 JRC analysis of the event JRC is responsible for

1. the operation of GDACS, www.gdacs.org that plays a major role in alerting the international community to humanitarian emergencies during natural disasters.

2. The coordination of the GTIMS2 Tsunami Alert network of seismological centres (Global Informal Monitoring System)

3. The management of the Copernicus Emergency Mapping Service, that is triggered to provide satellite data on very short time scales in case of major incidents

3.1 JRC/GDACS alerts

The alerts of GDACS (Green, Orange, Red) are elaborated based on the severity of the event, the population involved and the vulnerability of the countries. Apart from the Alerts published on the web, GDACS also sends e-mail and SMS alerts to subscribed recipients; in the present event, xxxxx e-mails and xxxxx SMS messages were dispatched, few minutes after the event. GDACS also posts alerts in the main social media platforms, reaching over 500 followers on Facebook and over 2 000 on Twitter.

The events timeline is indicated in the following table

Table 1 – Timeline of GDACS events

Although GDACS is an automatic system and all the estimations are based on event detection and launch of dedicated calculations, the last value of the impact estimation has been obtained by perfoming a manual calculation few hours after the event, when more precise information on the fault mechanism were available from USGS. This is the reference calculation desscribed here: in the next days the reference calculation could change if more detailed information become available.

The conditions above have been obtained by USGS (solution 1)1 . The following table reports the lis of the first 20 locations reached by the Tsunami wave. The full list of location is present in the GDACS web site (see references). The calculation was performed with the following conditions:

1 http://earthquake.usgs.gov/earthquakes/eventpage/us20003k7a#scientific_tensor:us_us_20003k7a_mww

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Joint Research Centre, I-21020 Ispra (VA), Italy

Epicentre

Latitude: -31.60

Longitude: -71.70

Magnitude: 8.30

Depth: 24.0 (km, Middle of fault - hypocentre)

Water Depth: -232 (m)

Event Date: 16 Sep 2015 22:54

Fault Geometry

Displacement: 6 (m)

Width: 62 (km)

Lenght: 223 (km)

Strike: 353 (deg - North=0)

Dip: 19 (deg)

Rake 83 (deg)

The estimated maximum height was 7.5 m, in Los Vilos (31.92 S, 71.51 W) but many other locations are estimated to have been severely impacted by the Tsunami wave. These evaluations have also been used in order to identify the areas mostly affected for which the Copernicus Service was requested (see later).

Figure 3 – Estimated maximum height at the coast

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Joint Research Centre, I-21020 Ispra (VA), Italy

Time of Max Height Country Location Height ID

16 Sep 2015 23:16 Chile Maitencillo 3.7 -30.99 -71.64

16 Sep 2015 22:59 Chile Maitencillo 2.6 -31.30 -71.58

16 Sep 2015 23:25 Chile Quillaicillo 3.2 -31.41 -71.57

16 Sep 2015 23:32 Chile Angostura 4.9 -31.50 -71.55

16 Sep 2015 23:01 Chile Pichidangui 2.5 -32.13 -71.53

16 Sep 2015 23:01 Chile Totoralillo 2.6 -32.04 -71.53

16 Sep 2015 23:28 Chile Los Vilos 7.5 -31.92 -71.51

16 Sep 2015 23:01 Chile Quilimari 2.6 -32.12 -71.49

16 Sep 2015 23:28 Chile Conchali 7.5 -31.88 -71.49

16 Sep 2015 23:19 Chile Ingeniero Santa Maria 4.6 -32.23 -71.47

16 Sep 2015 23:48 Chile Guaquen 3.3 -32.30 -71.45

17 Sep 2015 00:32 Chile Quintero 3.9 -32.78 -71.54

16 Sep 2015 23:32 Chile Huentelauquen 4.9 -31.58 -71.53

16 Sep 2015 23:29 Chile Chigualoco 3.9 -31.75 -71.50

17 Sep 2015 00:11 Chile Pite 3.2 -32.52 -71.48

17 Sep 2015 00:20 Chile Las Cujas 2.7 -32.57 -71.47

16 Sep 2015 23:29 Chile Gauchal 3.9 -31.77 -71.47

17 Sep 2015 00:11 Chile Papudo 3.2 -32.51 -71.45

16 Sep 2015 23:48 Chile El Romeral 3.3 -32.42 -71.38

17 Sep 2015 00:26 Chile Ritoque 4.9 -32.83 -71.52

Table 2 – first 20 locations reached by the Tsunami wave. In some cases the wave arrived after 3-4 minutes

The comparison between measured and calculated sea level allows selecting the right scenario and the quality of the calculation.

The expected and measured sea level is compared in three locations: Coquimbo, Valparaiso and the Juan Fernandez Island. Those are not the only available tidal gauges: there are many more. Infact Chile strongly improved the installed instrumentation after the 2010 event. Those were chosen with the short time available for the analysis.

More detailed analysis will follow in the next weeks to fully characterize the event.

The analysis of the event shows that the main features of the event are captured by the calculations. In particular it is very important the fact that also this time, likewise in 2010, the sea level shows several periodic peaks caused by the bathymetry in front of Chilean coast that causes waves reflection (sloshing). The importance is that the waves tend to increase and the third wave is larger than the first one. In Juan Fernandez the arrival time is predicted correctly and the amplitude is slightly overestimated. The period instead is right.

Figure 4 Identification of the tidal gauges used for the comparison

Coquimbo

Valparaiso

Juan Fernandez

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Joint Research Centre, I-21020 Ispra (VA), Italy

Figure 5 – Sea level measured (red) and calculated (blue) in Coquimbo

Figure 6 -Sea level measured (red) and calculated (blue) in Valparaiso

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Joint Research Centre, I-21020 Ispra (VA), Italy

Figure 7 -Sea level measured (red) and calculated (blue) in Juan Fernandez Island

A more extended calculation has also been performed in order to understand the wave propagation in the Pacific Ocean. This calculation was performed with a rougher nodalization, as the cell size was 5 instead of 1 minute, as for the short range forecast.

The results indicate, see next figure, that most of the damage occurred in Chile; from the simulation the maximum wave height in various Pacific highlands does not exceed 1 m.

At the time of the report issuing the wave is still propagating in the Pacific Ocean and is expected to reach Japan tonight, at about 20:49 after several hours of travel time. The expected maximum height in Japan is about 0.2-0.3 m.

Figure 8 – Sea level in Kawaihae, Hawaii. The arrival time is at 13:30 of 17 Sep

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Joint Research Centre, I-21020 Ispra (VA), Italy

Figure 9 – Pacific wide simulation of the Chile event

3.2 The Global Tsunami Informal Monitoring System initiative-2

JRC, in collaboration with DG-ECHO has established the second edition of the Global Tsunami Informal Monitoring System (GTIMS-2) that is aimed at: providing a training opportunity for the Tsunami Warning Center in the Mediterranean And North Atlantic area (NEAMTWS) and to provide a 24/7 analytical support to the ERCC. The system is activated whenever an event of magnitude larger than Mw 7 is occurring. This time the system was activated and two of the three centers that are on duty this month (KOERI, Turkey and NOA, Greece) produced within 1 h from the event a first Flash report, followed after 2h by an extended report. A final report is expected within 24 h from the event by the other operational team (NIEP, Romania) and by additional two backup teams (IPMA, Portugal and CNRST, Maroc).

A dedicated application allows ERCC to follow the evolution of the event and eventually pose questions to the teams involved in the analysis. This is a first form of Scientific Partnership within the European Union that will be further developed in other initiatives of JRC together with other General Directions.

3.3 Copernicus Emergency Mapping Service

The Emergency Response and Coordination Centre of DG ECHO activated the EMS Copernicus Rapid Mapping service for the Earthquake in Chile on 17 September, at 09.34 UTC (Code EMSR137)..

3.4 Involvement with other services of the Commission

In case of significant events such as this earthquake, JRC provides scientific support to the Emergency Response and Coordination Centre (ERCC) of DG ECHO, through information bulletins (published in http://ercportal.jrc.ec.europa.eu/ ), dedicated maps and reports such as the present. JRC informed the ERCC with a Flash report from the GTIMS-2 service at 4:19 CEST and a preliminary analysis of the event at 5:35 CEST. During the day a more detailed map, including several layers was produced and sent to ERCC at 17:30 CEST (Appendix A).

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Joint Research Centre, I-21020 Ispra (VA), Italy

4 Response of the Chilean Authorities The official national agency of Chile responsible for issuing tsunami alerts is the Chilean Navy Hydrographic Service (http://www.shoa.cl/).

Their alerts had the following time sequence as depicted in their web site.

16-09-2015 19:54

72 KM AL NW DE PICHIDANGUI

17-09-2015 06:19 CANCELACION TOTAL DEL ESTADO DE ALARMA DE TSUNAMI 17-09-2015 05:18 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 17-09-2015 04:11 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 17-09-2015 03:06 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 17-09-2015 02:26 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 17-09-2015 01:30 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 17-09-2015 00:39 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 16-09-2015 23:19 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 16-09-2015 22:22 CANCELACION PARCIAL DEL ESTADO DE ALARMA DE TSUNAMI. 16-09-2015 21:50 ALARMA DE TSUNAMI PARA LAS COSTAS DE CHILE 16-09-2015 21:01 ALARMA DE TSUNAMI PARA LAS COSTAS DE CHILE 16-09-2015 20:42 ALARMA DE TSUNAMI PARA LAS COSTAS DE CHILE 16-09-2015 20:32 ALARMA DE TSUNAMI PARA LAS COSTAS DE CHILE 16-09-2015 20:12 ALARMA DE TSUNAMI PARA LAS COSTAS DE CHILE 16-09-2015 20:02 ALARMA DE TSUNAMI PARA LAS COSTAS DE CHILE

The initial countrywide tsunami alert was issued at 16-09-2015 20:02 (local time) referring to a Mw 7.9 Richter scale event occurring at 19:54 (local time), thus 8 minutes after the event. The second warning, 10 minutes later added arrival times while the 3rd (20:32 local time) updated the information with a new magnitude assessment of Mw 8.3 Richter and a measurement of 1.4 m at PICHIDANGUI. Further updates added additional measurements up to 21:50 (local time) when the reference magnitude was increased to Mw 8.4 Richter and several measuring stations reporting tsunami amplitudes up to 4.5 m.

TOCOPILLA:0.14 [M]. MEJILLONES:0.16 [M]. ANTOFAGASTA:0.20 [M]. PAPOSO:0.17 [M]. TALTAL:0.18 [M]. SAN FELIX:0.61 [M]. CHANARAL:0.70 [M]. CALDERA:0.65 [M]. HUASCO:0.64 [M]. COQUIMBO:4.50 [M]. PICHIDANGUI:1.90 [M]. JUAN FERNANDEZ:1.05 [M]. QUINTERO:1.90 [M]. VALPARAISO:1.78 [M]. SAN ANTONIO:1.20 [M]. BUCALEMU:0.54 [M]. CONSTITUCION:0.56 [M]. ISLA QUIRIQUINA:0.14 [M].

Based on sea level measurements and tsunami wave modelling, the alert was partially lifted for various parts of the country starting at 22:22 (local time) roughly 2:30 hours after the event. Further partial cancellations followed until the total countrywide alert cancellation at 06:19, more than 10 hours after the event.

Figure 10 - Inidication of the location reported in the Chilean messages

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Joint Research Centre, I-21020 Ispra (VA), Italy

5 Meteorological Situation Besides today's chance of rain showers during warm hours of the day the next significant weather event (change) is expected to take place during 22 to 23 September (next Tuesday & Wednesday) with overcast skies / moderate rain and a considerable drop in temperature.

Winds also will be increased (15 to 25 km/h) and will be mostly from northeastern directions. Special care should be taken for people that are exposed to weather conditions especially during night hours.

Based on a vast combination of maps coming both the European Center for Medium-Range Weather Forecast (ECMWF) and the Global Forecast System from NOAA the following weather could be envisaged.

TODAY 17 September 2015

Partly cloudy in morning hours with a chance of showers developing during afternoon. Maximum temperature to reach 18 degrees Celsius. Winds from southwest directions with 10 to 15 km/hour. Chance of rain during warm hours of the day at about 30%.

TOMORROW 18 September 2015

Partly cloudy. Maximum temperature to reach 18 degrees Celsius. Winds from southwest directions with 10 to 15 km/hour.

LONG TERM FORECAST

FROM 19 TO 21 September 2015

Partly cloudy. No significant change in temperature. Winds from west/southwest

directions with 5 to 10 km/hour.

FROM 22 TO 23 September 2015

Cloudy with rain with considerable drop in temperature. Winds mostly from northeastern directions with 15 to 25 km/hour.

FROM 24 TO 26 September 2015

Mostly cloudy with no significant change in temperature. Winds mostly from southwest directions with 10 to 15 km/hour.

Figure 11 - GFS Precipitation Forecast valid for 18 Sep 2015

Figure 12 - GFS Precipitation Forecast valid for 24 Sep 2015

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Joint Research Centre, I-21020 Ispra (VA), Italy

6 References For updated information on the disaster, please consult the following web sites:

Global Disaster Alert and Coordination System: http://www.gdacs.org ERCC portal: http://ercportal.jrc.ec.europa.eu/ Pacific Tsunami Warning Centre: http://ptwc.weather.gov/ ONEMI: http://www.onemi.cl/ USGS: http://earthquake.usgs.gov/earthquakes/eventpage/us20003k7a#general_summary SNAM Chile: http://www.snamchile.cl/

GFS: http://www.cpc.ncep.noaa.gov/products/african_desk/cpc_intl/samerica For the latest news on damage, impact etc the following web sites were used:

BBC: http://www.bbc.com/news/world-latin-america-34275783 La Nacion: http://www.lanacion.cl/ La Segunda: http://www.lasegunda.com/

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Joint Research Centre, I-21020 Ispra (VA), Italy

ANNEX I: Detailed map of the earthquake and tsunami

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Joint Research Centre, I-21020 Ispra (VA), Italy

ANNEX II: Aftershocks Prior to the 8.3Mw earthquake, no major foreshock occurred. After the main shock two important events close to Mw 7 occurred.

Figure 13 Pre- and aftershocks

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Joint Research Centre, I-21020 Ispra (VA), Italy

ANNEX III: Social Media Analysis Social media analysis by the JRC, showing number of tweets per keyword (1st graph). Large presence of Tsunami and Chile words happen after the event.