Israel has planned an extravaganza this spring to celebrate the 40th anniversary of its independence, and the festivities -- some of them arranged to draw foreign tourists -- so far are scheduled to go on despite the recent violent civil clashes in the occupied West Bank and the Gaza Strip.

The yearlong calendar of commemorative events includes a special $11.5-million staging of Giuseppe Verdi's opera "Nabucco" in a vast amphitheater alongside the historic walls of ancient Jerusalem. The unusual production is being billed as 1988's most important artistic event anywhere, and presumably the largest and "the most costly opera ever mounted in all of operatic history."

Tourism officials hope to attract as many as 70,000 tourists, a great many of them Americans, to the 12 performances scheduled from May 15 to 29 in the 7,800-seat outdoor theater called the Sultan's Pool. A historic site, the 3,000-year-old Sultan's Pool appropriately is one of the actual settings for the plot of the opera. "Nabucco" tells the story of Babylonian King Nebuchadnezzar's (Nabucco) conquest of Jerusalem in 587 B.C., the exile of its residents and, as an opera brochure puts it, "the ultimate triumph of the Jewish people's faith and spirit over the military power of the Babylonians."

As a tale of struggle for self-determination, "Nabucco" is considered by Israelis to be still politically relevant today. Its great chorus, "Va, pensiero," is sung by the opera's exiled Jews longing for their homeland.

The opera naturally lends itself to a staging spectacular. The highlight of the independence celebration, it will feature a starring cast and chorus of some 250 singers, as many as 800 other nonsinging performers and the Royal Philharmonic Orchestra of London. The price for a single ticket, depending on location, ranges from $260 to $780 -- except on opening night when the range is $400 to $1,000 per ticket.

"It will be a once-in-a-lifetime opportunity," says executive producer Michael W. Ecker, who got his start in music as a Vienna choirboy. Ecker is president of OOS-Opera on Original Sites Inc., a new Swiss-based company formed to present operas on the actual sites used in the story line.

The harrowing events of recent weeks -- the continuing clashes between armed Israeli troops and stone-throwing Palestinian Arab protesters in the occupied territories -- undoubtedly have raised questions about the safety of visitors heading to Israel for the big celebration. The government has moved with force to quell the disturbances, firing on the demonstrators and using clubs, and the death toll now numbers more than four dozen. Obviously, the violence is of great con- cern to travelers: Is a sightseeing trip to Israel safe?

The Israelis say yes, arguing that the disturbances so far have mostly been limited to areas not normally visited by tourists. In addition, travelers can expect to see heavier security forces in evidence at tourist sites.

Press coverage of the violence "is not flattering to Israel," says Joseph Shoval, the embassy attache' in Washington for tourism affairs, "and it's embarrassing. But it has nothing to say about the safety of the people living in the country or the 1.5 million tourists who come every year ... Safety and security are guaranteed."

For example, much of the rioting has occurred in Gaza, Shoval says, which has little attraction for tourists. "We say Gaza is not a place where Jesus visited, where Moses visited. It's not a holy place and never has been." However, a brief Arab demonstration did occur one day in January in the Old City of Jerusalem, a popular tourist site. Shoval sees it as no reason to be dissuaded from a visit.

As of last week, the State Department, which issues travel advisories or warnings about the world's trouble spots, had not changed an indefinite advisory it first distributed in 1982. The advisory cautions that conditions in the West Bank and the Gaza Strip affecting the safety of travelers "can change with little warning." Any U.S. visitor leaving Jerusalem for the West Bank should contact the U.S. consulate-general's office in Jerusalem. Those headed for the Gaza Strip should check with the U.S. Embassy in Tel Aviv.

The disturbances appear to be having some adverse effect on travel to Israel this year, but just how badly is not easy to determine. There have been cancellations, and some tour organizers say they are not getting the advance bookings they might expect at this time of year. It is thought the dropoff stems from safety fears and are not protests against Israeli actions. Israeli tourism officials, however, discount the impact of the clashes.

"Considering the amount of bad publicity, one would have expected the collapse of the tourist industry," says Shoval. However, any losses have been "insignificant," and new bookings for April and May -- the peak period for commemorative events -- "don't show any dramatic drop."

Joram Kagan, vice president of Unitours of Greenwich, Conn. agrees. "We have not seen signs of cancellations. This is very encouraging." His firm sends about 7,000 tourists to Israel annually.

On the other hand, Avi Kenet, vice president of Galilee Tours of New York, says, "It's quite obvious that it {the situation in Israel} has an influence. It's quite significant." The problem has not been so much cancellations as it has been a slowdown in bookings, principally from first-time travelers to Israel.

"Our future bookings are slow now," Kenet says, adding that "a distinction must be made between people who have been to Israel before and those people who have never been there. The only image they get is very unpleasant." Galilee Tours sends about 4,000 Americans to Israel annually, about 60 percent of them non-Jewish tourists. "They are more sensitive," he says, to the reports of trouble.

John McCommons, president of Western World Tours of Santa Barbara, which specializes in tours for religious groups, is having a somewhat different experience. In business for 27 years, his firm has a Holy Land tour organized for 200 American Protestants in April, and to date only a handful have canceled because of safety concerns. However, he says, he got word from a travel agent that a tour for 40 Jewish travelers for Passover in Israel was being canceled because too many people had dropped out.

On the plus side, Shoval points out that Israel is an especially good travel bargain this year. This is because the exchange rate between the U.S. dollar and the new shekel generally has remained stable, while the dollar has plummeted in relation to several West European currencies. Typically, a room in one of Israel's finest hotels with a full breakfast can be found for $70 to $120 a night for two people. This compares with $150 or much more for similar deluxe lodgings in London, Paris, Venice and Rome.

Meanwhile El Al, the Israeli airline, has announced plans to add flights to Israel from North America because of the "Nabucco" production, and tourism officials expect TWA to do the same. In anticipation of increasing tourism, Israel has built 7,000 new hotel rooms in the past three years, including a new 525-room Hyatt Regency in Jerusalem. The Hyatt's rate for a room for two is $120 a night.

A number of tour operators and other organizations, including the Metropolitan Opera Guild of New York, are offering group tours to Israel that include a performance of Verdi's opera. Tours also are available that take in performances of the Israel Festival, an annual month-long performing arts festival in Jerusalem that runs from May 14 to June 11. An especially strong program featuring national and international artists -- among them famed American conductor Leonard Bernstein -- has been arranged for the anniversary year.

Independence Day, Israel's official birthday, falls on April 21 this year. It is a date that takes a little explaining.

Israel actually declared its sovereignty on May 14, 1948, but May 14 is not the date that is celebrated annually. In 1948, May 14 coincided with the fifth day of Iyar, a month of the Hebrew calendar. It is the Hebrew date, Iyar 5, that is regarded as Independence Day. As a result, Independence Day floats on the Western calendar.

Indeed, Israel's commemorative year -- according to the Hebrew calendar -- began with the Jewish New Year last September and concludes next September. Though the year is now well on its way, the biggest events are yet to come.

Opera lovers seeking the unique should be tempted by Jerusalem's "Nabucco," both for its historic setting and its noted voices. Four alternating casts include such luminaries as Grace Bumbry and Ghena Dimitrova in the leading role of Abigaille, the daughter of Nabucco; Cleopatra Ciurca as Fenena, another daughter; Renato Bruson and Ingvar Wixell as Nabucco; and Paul Plishka as Zaccaria, high priest of the Jews. Michel Plasson, who heads the orchestra of Toulouse, France, will conduct the Royal Philharmonic Orchestra of London.

Should the 12 performances from May 15 to 29 sell well, there is a possibility that four additional performances will be scheduled through June 2. Ticket prices for all but the opening performance are $260, $460, $560 and $780 for VIP seating. On opening night, the prices are $400, $600, $700 and $1,000. Gail Sloan, a spokeswoman for the production, says they can be purchased by American tourists only in the United States, either individually or as part of a tour package.

Among the other big events -- both annual and special -- of Israel's 40th anniversary:

Israel Festival, May 14 to June 11: "Nabucco" steals the spotlight in this month-long festival of the arts in Jerusalem, but the 1988 program features several other important productions. More than 70 events and 200 performances are scheduled during the month.

As a sample, the Israeli Philharmonic Orchestra will present two special concerts, one conducted by Leonard Bernstein (June 2) and another by Polish composer Kristof Penderecki, who will offer some of his own works (May 15). Famed choreographer Maurice Bejart will present his company in a world premiere of a ballet based on the play "The Dybbuk" (May 25 and 26). The Lar Lubovitch Dance Company of New York will offer its own premiere, a ballet dedicated to Israel (May 18 and 19). And violinist Pinchas Zukerman joins in a dramatic musical play, "Through Roses," which deals with the Holocaust (May 25 to 30).

Independence Day, April 21: The official ceremonies really begin a day earlier on April 20, Israel's Memorial Day. To conclude Memorial Day and commence Independence Day, an impressive torch-lighting ceremony is staged on Mount Herzel in Jerusalem. The chairman of the Knesset, Israel's parliament, lights the first torch, and 12 more are lighted, symbolizing the 12 tribes of Israel. Among the events of April 21 are a open-air concert in Jerusalem performed by the Israel Philharmonic Orchestra and conducted by Zubin Mehta and a parade of international marching bands through the streets of Jerusalem.

En Gev Festival, April 2 to 5: Begun in 1944, this major arts festival in the kibbutz of En Gev on the Sea of Galilee features national and international artists. The emphasis is on classical music, dance and popular music.

Tel Aviv Festival of Vocal Music, April 2 to 6: Held in Jaffa, an old section of Tel Aviv, the festival plays host to some of the world's best vocal ensembles and choirs. Many of the week's concerts are presented against the backdrop of historic sites in the reconstructed Old City.

Mimouna, April 9: A particularly colorful event, this nationwide folk festival, held on the last night of the Passover Feast, focuses on the heritage of Israel's Jews from North Africa. Many celebrants appear in traditional dress, and there is feasting on the traditional dishes of North Africa.

"Come to the Negev," July 5 to 13: For nine days, the nation turns its spotlight on the reclaimed desert area of the Negev in southern Israel for this special anniversary event. A real mix of activities in scattered communities includes car, camel and bicycle races; a runner's marathon; historic hikes retracing famous military campaigns; an international hot-air balloon competition; song festivals; sound and light shows; folk dancing; agricultural and ethnic exhibits and "Rock in the Desert," a major rock music festival that is expected to draw some of the world's most famous performers.

Festival at Masada, Oct. 13: A concluding event in Israel's year-long anniversary, it makes dramatic use of the historic mountain fortress of Masada. Scheduled are a sound and light show, a performance by the combined voices of Israel's finest choirs of Mahler's Second Symphony and a children's torchlight parade.

A traveler to Israel who wants to see "Nabucco" can purchase a tour package from one of more than a dozen travel organizations. At the top of the scale is an all-deluxe week that includes a round-trip flight on the supersonic Concorde for about $10,000 per person. More realistic packages for air fare, lodging and "Nabucco" begin at about $1,600 to $1,800 per person.

Among the possibilities:

The champagne special: For $9,999 per person (double occupancy, of course), you can take in the opening performance of "Nabucco" on a five-day, four-night quickee trip to Jerusalem aboard the Concorde. It is a private champagne flight, and seating for the opera is in one of the $1,000 VIP seats. Departure is from New York on May 12. Unitours, 411 West Putnam Ave., Greenwich, Conn. 06830, (800) 223-1780 or (203) 629-3900.

Metropolitan Opera Guild: There are two tour choices. The first is an eight-night sightseeing visit to London (three nights) and Israel, departing New York on May 15. The land price for lodging (at the Hyatt in Jerusalem), most meals, tickets to "Phantom of the Opera" in London and "Nabucco" and other Israel Festival performances in Jerusalem is $4,635 per person (double). A 14-night tour to Israel alone, departing May 24, is $5,611 per person (double). Air fare is extra. With overnight stays in Jerusalem, Tel Aviv and a kibbutz near Tiberius, the tour focuses on Israel's art, culture and music. For either tour, a guild membership fee is an additional $35. Members Travel Program, Metropolitan Opera Guild, 1865 Broadway, New York, N.Y. 10023, (212) 582-7500.

El Al: The Israeli airline's 10-night package is substantially cheaper. Prices for land arrangements range from $780 to $1,110 per person (double), depending on quality of accommodations. This provides sightseeing by motorcoach in Jerusalem, Galilee and Tel Aviv and adjacent areas; full breakfast daily and some other meals; and a ticket to "Nabucco." Air fare is an additional $999. Departures are May 18 and May 25. Contact El Al at (800) 223-6700 or a travel agent.

For other tours, consult the "Nabucco" information number provided below or a travel agency.

For information about "Nabucco" and the Israel Festival, including performance schedules and tour packages, or to order individual "Nabucco" or festival tickets, contact: Israel Music Events Inc., 725 Park Ave., New York, N.Y. 10021, (800) NABUCCO or (212) 439-1730.

For Israeli tourism information, contact: Israel Government Tourist Office, 3514 International Dr. NW, Washington, D.C. 20008, 364-5699.