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EERI SPECIAL EARTHQUAKE REPORT - MAY 1996

The February 17, 1996 Irian Jaya Earthquake and Tsunami

The information in this report was collected by an International Tsu-nami Survey Team (ITST), consist-ing of scientists and engineers from Indonesia, Japan, and the USA. The team visited the af-fected area from March 4 to 8, 1996.


Introduction

On February 17, 1996 at 05:59 GMT (14:59 local time) a major (MW = 8.2) earthquake occurred near Biak Island, Indonesia (S 0.6o, E 136.5o). It generated a deadly tsunami which reached a maximum measured height of 7.7 m. As of March 4, the official death toll from the earthquake and tsunami included 107 at Biak Island and 3 at Yapen Island. Fifty-one persons remained missing. About 100 per-sons were seriously injured, and 10,000 were made homeless. Biak and Yapen Islands are situated off the north shore of the Irian Jaya portion (western half) of the island of New Guinea.

Earthquake

Previous earthquakes in the area occurred in 1914 (7.9), 1957 (7.5) and 1979 (7.9). The duration time of rupture for the 1996 event was reported at 28 seconds. The Har-vard "quick" CMT solution sug-gests a MW = 8.2 low-angle thrust event in the New Guinea Trench, at 15 km depth, with a rupture length of 180 km and width of 50 km. However, USGS calculations indicate Mw = 7.9 and a depth of 21 km; the University of Tokyo reports Mw = 8.0 at a 33 km depth; and Caltech calculates MW = 8.1 at 33 km depth. The Biak earthquake was followed within one day by a flurry of aftershocks featuring an unusual diversity of focal mechanisms: thrust, normal, and strike-slip. The thrusting nature of the event suggests a complicated tectonic interaction for this region.

The epicenter was located in the Pacific Ocean north and east of Biak Island, a long, narrow strip of land (about 150 km by 30 km) which runs roughly east-west across the northern end of the Teluk Cenderawasih bay. Yapen Island, of similar size and orien-tation, lies about 50 km south of Biak, also in Teluk Cenderawasih.

In the village of Bosnik in eastern Biak, almost all the houses col-lapsed due to ground shaking. Many sand boils were observed by the ITST in this area of soft sand. In northern Biak 11 persons were killed, 183 houses collapsed, and 192 houses were heavily damaged by the shaking.

Tsunami

The earthquake generated a large tsunami, which struck the Irian Jaya coast with heights of about 5-7 meters. Reported tsunami heights include:

4 m at Manokwari (western New Guinea)
7 m at Sarmi (central New Guinea)
6-7 m at Korim (northern Biak)
3-5 m at Biak
7 m at Yapen Island


The tsunami caused damage as far away as Japan, where a wave height of nearly 1 m was reported and several fishing boats were washed away. A tsunami warning was issued at 17:00 local time in Japan; the first waves struck about 20 minutes later. No severe damage occurred in Japan, although this was the largest tsunami generated by a far-field earthquake to be recorded since the 1960 Chile earthquake and tsunami.

The ITST collected information on tsunami runup heights from meas-urements of clear tsunami traces and from eyewitness reports. On the northern coast of Biak, facing the tsunami source, the heights were 3-5 m, the largest measured on the island. Especially large tsunamis were observed in small bays such as Korim and Waru, suggesting concentration of tsu-nami energy or seiche action in the bays. The eastern part of Biak is surrounded by a shallow sea with many small islands. This region, close to the tsunami source, did not experience tsunamis as great as did the northern shore.

The maximum tsunami height of 7.7 m was measured at Farusi, Wardo in western Biak, which is located on the side of the island furthest from the tsunami source. A tsunami phenomenon such as a trapped wave on a coral reef may have caused this local phenomenon.

The most severe damage due to the tsunami occurred at Korim, where the height was 4-5 meters and the inundation area about 700 m long and 400 m wide. Sixty-four of the dead and 18 missing people were reported from the area in and around Korim. About 380 homes were completely destroyed by the inundation.

Remarkable sand deposition and erosion were observed along the coast at Korim. The volume of deposited sand was estimated to be about 3,000 m3. The volume of erosion estimated is less than that of deposition, suggesting that the tsunami transported the sand from the shallow sea bottom in the area around Korim.

In eastern Biak, local people report that the level of high tide is now 0.5 to 1.0 m higher than in the past, indicating the land in that area has subsided due to the earthquake.

To assist in planning the ITST survey, the tsunami simulation model TSUNAMI was used to esti-mate the probable tsunami heights along the Irian Jaya coast. Actual measurements on Biak Island compared well to the predicted values.

ITST Members

Indonesia: Mr. Subandono Dipo-saptono and Mr. Rahman Hidayat of BPPT; Dr. Nanang Tyas Puspito and Mr. Hamzah Latief of ITB; and Mr. Fusuni of BMG.

Japan: Dr. Fumihiko Imamura of Tohoku University, reader; Mr. Tomoyuki Takahashi, Mr. Ho Jun Lee, Mr. Shun-ichi Koshimura, Mr. Nobuya Horuchi, and Mr. Kazumori Kurayoshi of Tohoku University; Dr. Hideo Matsutomi of Akita University; Dr. Kouji Kofune of Port & Harbor Research Institute; Dr. Gary Watson of Kyoto University; and Dr. Yoshinobu Tsuji of the University of Tokyo.

USA: Mr. Andy Moore of the University of Washington; and Mr. Utku Kanoglu and Mr. Jose Berrero of the University of Southern California.

The reproduction and distribution of this report were funded by National Science Foundation Grant #CMS-9526408, EERI's Learning From Earthquakes Project.

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Korem Beach after earthquake -korem- North Biak, Korem Beach

Korem village in the North coast of Biak Island.


 About 50 meter from the beach.
  

Collected pictures 
from the field work in Biak, March 5 - April 5, 1996.

 

-last war- WORLD WAR II

Page 94

(Blank)

Page 95

SECOND REPORT
TO THE SECRETARY OF THE NAVY

Covering combat operations 1 March 1944 to 1 March 1945

By

FLEET ADMIRAL ERNEST J. KING
COMMANDER IN CHIEF,
UNITED STATES FLEET,
AND CHIEF OF NAVAL OPERATIONS

(Issued 27 March 1945)

Page 96

UNITED STATES FLEET
HEADQUARTERS OF THE COMMANDER IN CHIEF
NAVY DEPARTMENT
Washington 25, D. C.

12 March 1945

TO:
The Honorable James
Forrestal Secretary of the Navy,
Washington, D.C.

Dear Mr. Secretary:

Twelve months ago I presented to the late Secretary Knox a report of the
progress of our naval operations and the expansion of our naval
establishment since the beginning of the war.

Long before the war Frank Knox saw clearly and supported strongly the
necessity for arming the United States against her enemies. He knew that
a powerful Navy is essential to the welfare of our country, and fought
with all his energies to build a Navy that could carry the attack to the
enemy. How well he succeeded is now a matter of history.

The manner in which the Navy has carried the attack to the enemy during
the twelve months from 1 March 1944 to 1 March 1945 is the subject of
the report which I present to you at this time.

In reading this report, attention is especially invited to the
significant role of amphibious operations during the entire period. In
fact, amphibious operations have initiated practically all of the Allied
successes during the past three years.

Fleet Admiral Commander in Chief,
United States Fleet
and Chief of Naval Operations

Page 97

Introduction:

My previous report presented an account of the development of the Navy
and of combat operations up to 1 March 1944. This report covers the
twelve months from 1 March 1944 until 1 March 1945. Within this period
the battle of the Pacific has been carried more than three thousand
miles to the westward-from the Marshall Islands into the South China Sea
beyond the Philippines-and to the Tokyo approaches. Within this same
period the invasion of the continent of Europe has been accomplished.
These successes have been made possible only by the strength and
resolution of our amphibious forces, acting in conjunction with the
fleet.

During these twelve months, there occurred the following actions with
the enemy in which the United States Navy took part

20 March 1944 Landings on Emirau Island, St. Matthias Group, Northeast of New Guinea
Bombardment of Kavieng, New Ireland
30 March- Carrier Task Force Attacks on Western Carolines 1 April 1944
22 April 1944 Landings in Hollandia Area, New Guinea
29 April- Carrier Task Force Attacks on Central and Eastern 1 May 1944 Carolines
17 May 1944 Landings in Wakde Island Area, New Guinea
19-20 May 1944 Carrier Task Force Attach on Marcus Island
23 May 1944 Carrier Task Force Attack on Wake Island
27 May 1944 Landings on Biak Island, Dutch New Guinea
6 June 1944 Invasion 0f Normandy
11-14 June 1944 Preliminary Carrier Task Force Attacks on Marianas Islands
13 June 1944 Bombardment of Matsuwa Island, Kurile Islands
15 June 1944 Landings on Saipan, Marianas Islands
15-16 June 1944 Carrier Task Force Attacks on Iwo Jima and Chichi Jima, Volcano and Bonin Islands
17 June 1944 Capture of Elba, Italy
19-20 June 1944 Battle of the Philippine Sea
23-24 June 1944 Carrier Task Force Attacks on Pagan Island, Marianas Islands
24 June 1944 Carrier Task Force Attack on Iwo Jima, Volcano Islands
25 June 1944 Bombardment of Cherbourg, France
26 June 1944 Bombardment of Kurabu Zaki, Paramushiru,Kurile Islands
2 July 1944 Landings on Noemfoor Island, Dutch New Guinea
4 July 1944 Carrier Task Force Attacks on Iwo Jima, Chichi Jima and Haha Jima, Volcano and
Bonin Islands
21 July 1944 Landings on Guam, Marianas Islands
24 July 1944 Landings on Tinian, Marianas Islands
30 July 1944 Landings in Cape Sansapor Area, Dutch New Guinea
4-5 August 1944 Carrier Task Force Attacks on Iwo Jima and
Chichi Jima Volcano and Bonin Islands
15 August 1944 Invasion of Southern France


Page 98

31 August- Carrier Task Force Attacks on Iwo Jima, 2 Sept. 1944 Chichi Jima and Haha Jima, Volcano and
Bonin Islands
6-14 Sept. 1944 Preliminary Carrier Task Force Attack on Palau Islands
7-8 Sept. 1944 Carrier Task Force Attacks on Yap
9-10 Sept. 1944 Carrier Task Force Attacks on Mindanao,Philippine Islands
12-14 Sept. 1944 Carrier Task Force Attacks on the Visayas,Philippine Islands
14-15 Sept. 1944 Carrier Task Force Attacks on Mindanao, Celebes and Talaud
15 Sept. 1944 Landings on Peleliu, Palau Islands Landings on Morotai
17 Sept. 1944 Landings on Angaur, Palau Islands
21-22 Sept. 1944 Carrier Task Force Attacks on Manila, Philippine Islands
23 Sept. 1944 Landing on Ulithi
24 Sept. 1944 Carrier Task Force Attacks on the Visayas,
Philippine Islands
28 Sept. 1944 Landings on Ngesebus, Palau Islands
9 Oct. 1944 Bombardment of Marcus Island
10 Oct. 1944 Carrier Task Force Attack on Okinawa Island, Nansei Shoto
11 Oct. 1944 Carrier Task Force Attack on Aparri, Luzon, Philippine Islands
12-15 Oct. 1944 Carrier Task Force Attacks on Formosa and Luzon
18-19 Oct. 1944 Carrier Task Force Attacks on Northern and Central Philippines
20 Oct. 1944 Landings on Leyte, Philippine Islands
21 Oct. 1944 Carrier Task Force Attacks on Luzon and the Visayas, Philippine Islands
23-26 Oct. 1944 Battle for Leyte Gulf
5,6,13,14,19, Carrier Task Force Attacks on Luzon, Philippine 25 Nov. 1944 Islands
11 Nov. 1944 Carrier Task Force Attack on Ormoc Bay, Leyte, Philippine Islands
11-12 Nov. 1944 Bombardment of Iwo Jima, Volcano Islands
21 Nov. 1944 Bombardment of Matsuwa Island, Kurile Islands
7 Dec. 1944 Landings at Ormoc Bay, Philippine Islands
8, 24, 27 Air-surface Attack on Iwo Jima, Volcano Islands Dec. 1944
14, 15,16 Carrier Task Force Attack on Luzon, Dec. 1944 Philippine Islands
15 Dec. 1944 Landings on Mindoro, Philippine Islands
3-4 Jan. 1945 Carrier Task Force Attacks on Formosa
5 Jan. 1945 Bombardment of Suribachi Wan, off Paramushiru, Kurile Island
Air-surface Attack on Iwo Jima, Chichi Jima and Haha Jima, Volcano and Bonin Islands
6-7 Jan. 1945 Carrier Task Force Attacks on Luzon, Philippine Islands
9 Jan. 1945 Landings at Lingayen Gulf, Luzon, Philippine Islands Carrier Task Force Attack on Formosa
12 Jan. 1945 Carrier Task Force Attack on French Indo-China Coast
15 Jan. 1945 Carrier Task Force Attack on Formosa
16 Jan. 1945 Carrier Task Force Attack on Hong Kong, Canton and Hainan, China
21-22 Jan. 1945 Carrier Task Force Attack on Formosa and Nansei Shoto
24 Jan. 1945 Air-surface Attack on Iwo Jima, Volcano Islands
29-30 Jan. 1945 Landings in Subic Bay Area, Luzon, Philippine Islands
31 Jan. 1945 Landing at Nasugbu, Luzon, Philippine Islands
13-15 Feb. 1945 Bombardment of Manila Bay Defenses,Philippine Islands
14 Feb. 1945 Landings at Mariveles, Luzon, Philippine Islands
16 Feb. 1945 Landings on Corregidor Island, Luzon,Philippine Islands
16-17 Feb. 1945 Carrier Task Force Attack on Tokyo

Page 99

19 Feb. 1945 Landings on Iwo Jima, Volcano islandsBombardment of Kurabu Zaki, Paramushiru,
Kurile Island
25-26 Feb. 1945 Carrier Task Force Attack on Tokyo and Hachijo Jima
28 Feb. 1945 Landings on Palawan, Philippine Islands